Vaccine composition for the treatment or prevention of hepatitis a infection

Abstract

The present disclosure relates to Extracellular Vesicles, such as exosomes, comprising hepatovirus viral capsids or hepatovirus antigenic polypeptides useful as vaccine compositions to treat and / or prevent hepatitis A virus infection. The present disclosure also relates to methods of producing such EVs, e.g, exosomes, and uses thereof.

Description

[0001] Vaccine composition for the treatment or prevention of hepatitis A infection FIELD OF DISCLOSURE The present disclosure relates to Extracellular Vesicles, such as exosomes, comprising hepatovirus viral capsids or hepatovirus antigenic polypeptides useful as vaccine compositions to treat and / or prevent hepatitis A virus infection. The present disclosure also relates to methods of producing such EVs, e.g, exosomes, and uses thereof. BACKGROUND Hepatitis A, caused by hepatitis A virus (HAV), remains a common infectious vaccine- preventable disease, which still causes thousands of cases worldwide. Two examples are the epidemics occurring since 2016 in the homeless group in the US (United States of America), which affected over 44,000 patients, with 27,000 hospitalizations and almost 500 deaths, and the outbreak occurred in 2018-2019 in the men-having-sex- with-men group, affecting over 3,000 patients in Europe and the US. The affordability of classical inactivated virus vaccines require strains with high replication capacity producing high antigen yields, administered combined with potent adjuvants. Although classical inactivated hepatitis A vaccines do exist, their production is extremely costly and time-consuming, due to the very poor replication of the cell- culture adapted virus strains. In consequence, vaccine supply shortages are common and there is no capacity for a universal vaccination. The present invention confronts this problem by providing a new vaccine composition against Hepatitis A. BRIEF DESCRIPTION OF THE INVENTION A first aspect of the invention refers to a composition, preferably a vaccine composition, capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, the composition comprising Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, wherein the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are obtained by a method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides; b. infecting said cell line with a hepatovirus or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids or hepatovirus antigenic polypeptides; and c. recovering, isolating, and / or purifying the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, or the cell supernatant comprising the same; wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs; and wherein the composition is for use in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject. In some embodiments, the composition for use comprises hepatovirus viral capsids, and more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs. In some embodiments, the hepatovirus viral capsids are inactivated hepatovirus viral capsids or the method comprises an inactivation step of the hepatovirus viral capsids. In some embodiments, said cell line is selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), wherein preferably, said cell line is the FRhK-4 cell line or Vero cells. In some embodiments, the culturing step of the cell line to provide the culture supernatant is carried out by growing the cells, preferably Vero cells, in a cell medium in the absence of serum. In some embodiments,the Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are exosomes. In some embodiments, the hepatovirus is the human hepatitis A virus (HAV). In some embodiments, the genetic element of interest is selected from the group consisting of any DNA, RNA or polynucleotide analogues thereof encoding a member selected from the group consisting of proteins or fragments of proteins of at least a hepatovirus antigenic polypeptide. In some embodiments, the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. In some embodiments, the EVs are naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting the cell line with the HM175-HP strain (HP). In some embodiments, the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. In some embodiments, the protein shell of the viral capsid is of SEQ ID NO 1, the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. A further aspect of the invention refers to a vaccine composition, comprising naturally occurring EVs loaded with hepatovirus viral capsids capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs. In some embodiments of this further aspect, the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. In some embodiments of this further aspect, the protein shell of the viral capsid is of SEQ ID NO 1 and the EVs are exosomes. In some embodiments of this further aspect, the vaccine composition comprises naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting a cell line selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably FRhK- 4 cells or Vero cells, with the HM175-HP strain (HP), wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs. In some embodiments of this further aspect, the hepatovirus viral capsids produced by the HM175-HP strain (HP) are inactivated hepatovirus viral capsids. A further aspect of the invention refers to the use of the composition as defined in any of the previous aspects, in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject. A still further aspect refers to a method for producing a composition comprising EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides (from hereinafter the method of the invention), the method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides; b. infecting said cell line with a hepatovirus or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids or hepatovirus antigenic polypeptides; and c. recovering, isolating, and / or purifying the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, or the cell supernatant comprising the same; wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs. In some embodiments of the still further aspect of the invention, the cell line is infected with a hepatovirus, and wherein more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of the hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs, and wherein preferably the method comprises an inactivation step of the hepatovirus viral capsids. In some embodiments of the still further aspect of the invention, said cell line is selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably, FRhK-4 cells or Vero cells. In some embodiments of the still further aspect of the invention, the culturing step of the cell line to provide the culture supernatant is carried out by growing the cells, preferably Vero cells, in a cell medium in the absence of serum. In some embodiments of the still further aspect of the invention, the Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are exosomes. In some embodiments of the still further aspect of the invention, the hepatovirus is the human hepatitis A virus (HAV). In some embodiments of the still further aspect of the invention, the genetic element of interest is selected from the group consisting of any DNA, RNA or polynucleotide analogues thereof encoding a member selected from the group consisting of proteins or fragments of proteins of at least a hepatovirus antigenic polypeptide. In some embodiments of the still further aspect of the invention, the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. In some embodiments of the still further aspect of the invention, the EVs are naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting a cell line selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC- 5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably FRhK-4 cells or Vero cells, with the HM175-HP strain (HP), wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs. In some embodiments of the still further aspect of the invention, the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. In some embodiments of the still further aspect of the invention, the protein shell of the viral capsid is of SEQ ID NO 1, the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. A further aspect of the invention refers to a composition comprising EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides obtained or obtainable by the method of the invention. A further aspect of the invention refers to the composition of the previous paragraph for use in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject. BRIEF DESCRIPTION OF THE FIGURES Fig. 1. Upper panel. One-step growth curve of HP (continuous line) and L0 (discontinuous line) strains in Vero cells in the absence of Fetal calf serum (FCS) and using a multiplicity of infection of 0.05. The yield of virus in the supernatant is 1000X higher for the HP strain. Lower left panel. Proportion of HP and L0 capsids co- localizing with ALIX in confocal microscopy analysis: 53% and 35% of the HP and L0 capsids, respectively, co-localized with ALIX. Lower right panel. Proportion of HP and L0 capsids immunoprecipitated with an anti-ALIX antibody. Compared to an anti-HAV antibody, the anti-ALIX antibody was able to precipitate 55% of the HP capsids and only 28% of the L0 capsids. Fig. 2. Kinetics of production of total anti-HAV IgG (anti-L0) in BALBC mice after immunizing with nHP with alumina vs eHP without alumina. Titers were determined by a sandwich ELISA. Fig.3. Neutralization of L0 infectivity (wild type-like strain). Neutralization is expressed as the Log10 of the number of units able to neutralize 50.000 infectious units in 50% of the replicas in FRhK-4 cells. The average neutralization titre is 102.3450N50U / ml of sera for eHP particles without alumina vs 102.2950N50U / ml of sera for nHP particles with alumina. The percentage of positivity (number of BALBC mice producing neutralizing antibodies out of the total immunized mice) is similar between both groups. Fig. 4. Kinetics of production of total anti-HAV IgG (anti-L0) in BALBC mice after immunizing with nL0 with alumina vs eHP without alumina. Titers were determined by a sandwich ELISA. Fig. 5. Ratio of anti-HAV IgG2a / IgG1 in BALBC mice immunized with nL0 with alumina vs eHP without alumina. Titers were determined by a sandwich ELISA. Fig.6. Neutralization of L0 infectivity (wild type-like strain). Neutralization is expressed as the Log10 of the number of units able to neutralize 50.000 infectious units in 50% of the replicas in FRhK-4 cells. The average neutralization titre is 102.3450N50U / ml of sera for eHP particles without alumina vs 102.2150N50U / ml of sera for nHP particles with alumina. The percentage of positivity (number of BALBC mice producing neutralizing antibodies out of the total immunized mice) is similar between both groups. Fig.7. Titers of negative sense HAV RNA in liver from vaccinated and non-vaccinated MAVS- / - (left panel) and IFNR- / - (right panel) mouse models after an HAV challenge. Different letters over the box designate significant differences (p<0.001). In the MAVS- / -mouse model we used the HAVRIX vaccine as a control. The reduction of the negative sense HAV RNA (antigenome) was statiscally higher (p<0.001) in all vaccinated groups compared to the non-vaccinated group. In the eHP vaccinated mice this reduction was even higher. The nL0 vaccine and the HAVRIX vaccines, being similar in terms of composition, showed as expected the same level of reduction. In the IFN- / - mouse model, which is less sensitive to virus replication, only the eHP vaccine showed a significant (p<0.01) reduction of negative RNA copy numbers, compared to the non- vaccinated group. In both models, the eHP vaccinated group show a statiscally higher reduction (p<0.001) compared to the nL0 plus alumina vaccinated group (nL0 could be considered similar to a standard vaccine). Fig.8. HAV shedding in faeces expressed as the Log10 Genome copies / g of faeces in the MAVS- / - model. The HAVRIX vaccine was used as a control. All vaccinated groups induced statistically significant reductions in virus shedding compared to the non-vaccinated group: eHP (p<0.001), HAVRIX and eL0 (p<0.01) and nL0 and nHP (<0.05) The eHP vaccine showed the highest reduction. Fig.9. HAV shedding in faeces expressed as the Log10 Genome copies / g of faeces in the IFNR- / - model. All vaccinated groups showed a reduction in virus shedding but was statistically significant only in the nL0 and eHP vaccinated groups (p<0.05). Fig.10. Numbers of immune cell infiltrates in liver from vaccinated and non-vaccinated IFNR- / - mice after an HAV challenge. All vaccines tested induced a statistically significant (p<0.001) reduction of the number of liver infiltrates vs the non-vaccinated mice. DESCRIPTION OF EMBODIMENTS The present invention relates to a composition, preferably a vaccine composition, capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, the vaccine comprising Extracellular Vesicles (EVs) loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides, wherein the EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides are obtained by a method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus (human hepatitis A virus (HAV)) and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus (human hepatitis A virus (HAV)) or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides; b. infecting said cell line with a hepatovirus (human hepatitis A virus (HAV)) or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides; and c. recovering, isolating or purifying the EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides, or the cell supernatant comprising the same. As used herein “Hepatovirus” shall be understood as the Genus, in the Picornaviridae family, to which the hepatitis A virus belongs. The hepatitis A virus causes the hepatitis A, which is an acute inflammation of the liver preventable by vaccination. It is noted that preferably the term “Hepatovirus” can be specifically understood, throughout the present invention, as the hepatitis A virus (HAV). As used herein “viral capsids” shall be understood as the protein shell containing the virus genome. Hepatovirus capsids are preferably icosahedral with a diameter of 27 nm and contain 60 copies of each epitope. The immunodominant epitopes are discontinuous in nature. As used herein “cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant, EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides” shall be understood as a cell line expressing specific factors required for the IRES-dependent translation, and allowing the release of EVs containing capsids. Examples of such cell lines can be selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial). Preferably, said cell line is the FRhK-4 cell line or Vero cells. It is noted that the extracellular vesicles (EVs) present in the composition of the invention are delimited by a lipid bilayer membrane comprising an outer lipid layer and an inner lipid layer, wherein said EVs are internally loaded with the exogenous viral capsids or hepatovirus antigenic polypeptides; wherein said EVs have a diameter ranging from 20 to 500 nm, preferably ranging from 100 to 300 nm. As used herein, the term “extracellular vesicles (EVs)” refers to a heterogeneous population of particles released by virtually all living cells, which are delimited or encapsulated by a phospholipid bilayer and which carry lipids, proteins, nucleic acids and other molecules derived from the cell they are derived from. These vesicles mainly include microvesicles, released through the budding of the plasma membrane, and exosomes, derived from the endosomal compartment. Extracellular vesicles are referred to as “particles”, “microparticles”, “nanovesicles”, “microvesicles” and “exosomes”. The inherent cellular targeting properties of EVs that are dictated by their lipid composition and protein content as well as their intrinsic stability in circulation qualify these vesicles as vehicle for therapeutic agent delivery. Unless otherwise indicated, the term "at least" preceding a series of elements is to be understood to refer to every element in the series. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the present invention. Thus, unless otherwise noted, the expression “at least” or “at least one of” as used herein includes individually each of the recited objects after the expression and the various combinations of two or more of the recited objects unless otherwise understood from the context and use. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step. When used herein the term "comprising" can be substituted with the term "containing" or "including" or sometimes when used herein with the term "having". Any of the aforementioned terms (comprising, containing, including, having), whenever used herein in the context of an aspect or embodiment of the present invention may be substituted with the term "consisting of", though less preferred. When used herein "consisting of" excludes any element, step, or ingredient not specified in the claim element. When used herein, "consisting essentially of” does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. As used herein, the conjunctive term "and / or" between multiple recited elements is understood as encompassing both individual and combined options. For instance, where two elements are conjoined by "and / or", a first option refers to the applicability of the first element without the second. A second option refers to the applicability of the second element without the first. A third option refers to the applicability of the first and second elements together. Any one of these options is understood to fall within the meaning, and therefore satisfy the requirement of the term "and / or" as used herein. Concurrent applicability of more than one of the options is also understood to fall within the meaning, and therefore satisfy the requirement of the term "and / or." The term "subject" as used herein is a living multi-cellular vertebrate organisms, including, for example, humans, non-human mammals and (non-human) primates. The term "subject" may be used interchangeably with the term "animal" herein. As used herein, the terms “antigenic polypeptide” or similar terms refers to any molecule that stimulates a host's immune system to make an antigen-specific immune response, whether a cellular response or a humoral antibody response. Antigenic determinants may include proteins, polypeptides, antigenic protein fragments, antigens, and epitopes which still elicit an immune response in a host and form part of an antigen, homologues or variants of proteins, polypeptides, and antigenic protein fragments, antigens and epitopes including, for example, glycosylated proteins, polypeptides, antigenic protein fragments, antigens and epitopes, and nucleotide sequences encoding such molecules. Thus, proteins, polypeptides, antigenic protein fragments, antigens and epitopes are not limited to particular native nucleotide or amino acid sequences but encompass sequences identical to the native sequence as well as modifications to the native sequence, such as deletions, additions, insertions and substitutions. "Percent (%) amino acid sequence identity" with respect to proteins, polypeptides, antigenic protein fragments, antigens and epitopes described herein is defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the reference sequence (i.e., the protein, polypeptide, antigenic protein fragment, antigen or epitope from which it is derived), after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity. The same applies to "percent (%) nucleotide sequence identity", mutatis mutandis. Techniques for determining sequence identity between nucleic acids and amino acids are known in the art. Two or more sequences can be compared by determining their "percent identity." The percent identity of two sequences, whether nucleic acid or amino acid sequences, is the number of exact matches between two aligned sequences divided by the length of the shorter sequences and multiplied by 100. It should be noted that the “percentage of identity” as used herein is decided in the context of a local alignment, i.e., is based on the alignment of regions of local similarity between sequences, contrary to a global alignment, which aims to align two sequences across their entire span. Thus, in the context of the present invention, percentage identity is calculated only based on local alignment comparison algorithm. Local alignments for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for example, using publicly available computer software such as BLAST software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximum alignment over the the sequences being compared. Several documents are cited throughout the text of this specification. Each of the documents cited herein (including all patents, patent applications, scientific publications, manufacturer's specifications, instructions, etc.), whether supra or infra, are hereby incorporated by reference in their entirety. To the extent the material incorporated by reference contradicts or is inconsistent with this specification, the specification will supersede any such material. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention. In the present invention, the EVs are preferably naturally occurring vesicles. In fact, the EVs of the present invention are prepared by using a cell line susceptible to an infection with hepatovirus (human hepatitis A virus (HAV)) and able to release in a cell culture supernatant EVs loaded with viral capsids of hepatovirus (human hepatitis A virus (HAV)). Preferably, in a preferred embodiment of the first aspect of the invention, the cell line is selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial). It is herein noted that the Extracellular Vesicles (EVs) loaded with viral capsids or hepatovirus antigenic polypeptides of the present invention are capable of generating a potent immunogenic protective immune response against Hepatovirus in a subject in need thereof. Surprisingly, such protective response is generated without the need of any specific adjuvant as clearly indicated in the experimental section of this invention. Such experimental section shall be briefly summarized herein below (it is herein noted that the term “eHP” as used herein, shall be understood as quasi- enveloped particles of the HP strain, that is, the exosomes loaded with viral particles of the HM175-HP strain according to the present invention). As described in the present examples, a hepatitis A virus (HAV) strain with a fast- growing phenotype (HP strain) combined with an increased release of quasi-enveloped particles into the supernatant, thanks to the unique S134G replacement in the VP2 protein of the HP strain, which favours its interaction with the cellular protein ALIX, was used to infect Vero, MRC-5 and FRhK-4 cells. Comparative studies were carried out with the HM175-43c strain. A process of genomic selection and molecular breeding was employed to select the fast-growing HM175-HP strain (thereafter HP) as described in Pérez-Rodríguez F. J., D’Andrea L., de Castellarnau M., Costafreda M. I., Guix S., Ribes E., et al. (2016). Improving virus production through quasispecies genomic selection and molecular breeding. Sci. Rep.6:35962. 10.1038 / srep35962srep35962. Its ancestor is the HM175-43c strain (thereafter L0). The supernatant yields of quasi-enveloped particles of the HP strain (eHP) compared with the L0 strain (eL0) were: (i) 1.9X, 2X and 3.4X times higher in Vero, MRC-5 and FRhK-4 cells grown in the presence of fetal calf sera (FCS). (ii) 1000X higher in Vero cells adapted to grow in the absence of FCS and using a multiplicity of infection of 0.05. Part of these results are illustrated in figure 1. On the other hand, and as also shown in the examples, the eHP particles administered in the absence of any adjuvant are more immunogenic in BALB / C mice than naked particles (nHP) administered with alumina. Specifically, 5 X 107TCID50 of eHP particles in the absence of any adjuvant induced higher concentrations of total IgG antibodies recognizing the heterologous L0 capsids in a sandwich ELISA at shorter times post-inoculation (p.i.) than 5 X 107TCID50 of nHP particles. Specifically, the average highest reciprocal serum dilution recognizing L0 capsids is 32.000 vs 15.000 (eHP vs nHP with alumina) at day 55 p.i. and 38.000 vs 32.000 at day 63 p.i. Part of these results are illustrated in figure 2. In addition, eHP particles in the absence of any adjuvant induce equivalent levels of antibodies able to neutralize the L0 strain in vitro than the nHP particles with alumina. Specifically, the average neutralization titre is 102.3450N50U / ml of sera (units able to neutralize 50.000 infectious units in 50% of the replicas of FRhK-4 cells) for eHP particles vs 102.2950N50 U / ml of sera for nHP particles with alumina. See figure 3. Furthermore, the eHP particles, administered in the absence of any adjuvant in BALB / C mice, produce a similar total anti-HAV IgG response, an increase in the anti-HAV IgG2a response and a similar HAV neutralization response compared with a standard vaccine product, i.e. naked L0 particles (nL0) administered with alumina. In particular: ^ 5 X 107TCID50 of eHP particles administered in the absence of any adjuvant, induce equivalent concentrations of IgGs recognizing L0 capsids (average reciprocal serum dilutions of 27.000 vs 36.000, for eHP and nL0 with alumina, respectively) than 5 X 107TCID50 of nL0 with alumina. See figure 4. ^ The eHP particles, in the absence of any adjuvant, induce an enriched response of IgG2a antibodies compared with the nL0 capsids administered with alumina. Specifically, the anti-HAV IgG2a concentration is 3X higher in sera from mice inoculated with eHP particles, without any adjuvant, than in sera from mice inoculated with nL0 particles with alumina. The IgG2a / IgG1 ratio of eHP capsids with no adjuvant is 250X higher than nL0 capsids with alumina. See figure 5. ^ The eHP particles, administered in the absence of any adjuvant, induce equivalent levels of neutralizing antibodies compared with the nL0 capsids administered with alumina. Specifically, the HAV neutralization titre is 102.34 50N50U / ml of sera from mice inoculated with eHP particles and no adjuvant vs 102.2150N50U / ml of sera from mice inoculated with nL0 particles with alumina, respectively. See figure 6. Furthermore, as shown in the examples, vaccination with eHP particles, in the absence of any adjuvant, provided an increased protection against a HAV infection in the MAVS- / - mouse model (highly permissive to HAV replication) and the IFNR- / - (mouse model for HAV pathogenicity) compared with vaccination with nHP particles administered with alumina: ^ MAVS- / - and IFNR- / - mice vaccinated with eHP particles, in the absence of any adjuvant, and challenged with 108HAV infectious units show a 158X (99%) and 3X reduction (67%), respectively, in HAV negative RNA copies (anti-genome RNA) in the liver, which are intermediates of genome replication, compared with non-vaccinated and similarly challenged animals. In contrast, vaccination with nHP particles plus alumina induces a 38X (97%) and 1.9X reduction (47%), in MAVS- / - and IFNR- / - mice, respectively. Vaccination with the HAVRIX vaccine, which also contains alumina, induces a similar reduction compared to the nHP particles (26X and 96%) in the MAVS- / - mouse model. See figure 7. ^ IFNR- / - mice vaccinated with eHP particles, in the absence of any adjuvant, and challenged with 108HAV infectious units show a 6.7X reduction (85%) in liver infiltrates compared with non-vaccinated and similarly challenged animals. In contrast, vaccination with nHP particles plus alumina induces a 5X reduction (80%). See figure 10. ^ MAVS- / - and IFNR- / - mice vaccinated with eHP particles, in the absence of any adjuvant, and challenged with 108HAV infectious units show a 2.6X reduction (62%), and a 1.9X reduction (46%) in virus shedding in faeces, respectively, compared with non-vaccinated, and similarly challenged animals. In contrast, vaccination with nHP particles plus alumina induces a 1.4X reduction (27%) in both models. Vaccination with the HAVRIX vaccine induces a 2X (50%) reduction in the MAVX- / - model See figures 8 and 9. Moreover, the eHP particles, administered in the absence of any adjuvant, provide a higher level of protection against a HAV infection in an IFNR- / - mouse model than nL0 particles administered with alumina: ^ MAVS- / - and IFNR- / - mice vaccinated with eHP particles, in the absence of any adjuvant, and challenged with 108HAV infectious units show a 158X (99%) and 3X reduction (67%), respectively, in HAV negative RNA copies (anti-genome RNA), which are intermediates of genome replication, compared with non- vaccinated and similarly challenged animals. In contrast, nL0 vaccinated mice showed a 10X (90%) reduction in the MAVS- / - mouse model, similar to the reduction observed using the HAVRIX vaccine (26X reduction equivalent to a (96%), and a 1.17X reduction (21% reduction) in the IFNR- / - model. See figure 7. ^ IFNR- / - mice vaccinated with eHP particles, in the absence of any adjuvant, and challenged with 108HAV infectious units show a 6.7X reduction (85%) in liver infiltrates observe on H&E stained liver sections compared with non-vaccinated and similarly challenged animals. In contrast, nL0 vaccinated mice showed 4.6X reduction (78%) of liver infiltrates. See figure 10. ^ MAVS- / - and IFNR- / - mice vaccinated with eHP particles, in the absence of any adjuvant, and challenged with 108HAV infectious units show a 2.6X reduction (62%), and a 1.9X reduction (46%) in virus shedding in faeces, respectively, compared with non-vaccinated and similarly challenged animals. In contrast, nL0 vaccinated mice showed a 1.4X (27%) and a 2.3X (58%) reduction of viruses in faeces, in each mice model, respectively. See figures 8 and 9. Furthermore, the eHP particles, in the absence of any adjuvant, induce an enrichment of IgG2a compared with nL0 particles with alumina. This enrichment explains the higher level of protection of the eHP particles, in the absence of any adjuvant, in front of an HAV challenge. Finally, the eHP particles in the absence of any adjuvant provided an enrichment of the IgG2a response combined with an efficient protection against an HAV challenge in mice. It is noted that the hepatitis A virus (HAV) strain (HP strain) with a fast-growing phenotype combined with an increased release of quasi-enveloped particles into the supernatant, as described above, associated with its exclusive S134G replacement in the VP2 protein, which favours its interaction with the cellular protein ALIX, used to infect Vero, MRC-5 and FRhK-4 cells, can be obtained or produced by a process comprising the steps of: i) Synthesis of a cDNA based on the sequence GenBank KX088647; ii) cloning the cDNA into a transcription vector under the control of the SP6 or T7 promoters; iii) in vitro transcription of the cloned cDNA into an mRNA using the SP6 or T7 RNA polymerases; iv) transfection of FRhK-4 cells; v) Purification of HP infectious viruses; and vi) Growth of the HP viruses in FRhK-4 cells in the presence of 0.05 mg / ml Actynomicin D. Details of this process can be found in example 1 of the present invention. Therefore, in a first aspect of the invention, the present invention provides a composition, preferably a vaccine composition, capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, the vaccine comprising Extracellular Vesicles (EVs) loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides, wherein the EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides are obtained by a method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus (human hepatitis A virus (HAV)) and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus (human hepatitis A virus (HAV)) or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides; b. infecting said cell line with a hepatovirus (human hepatitis A virus (HAV)) or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids of hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides; and c. recovering, isolating or purifying the EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides, or the cell supernatant comprising the same. It is noted that the composition can comprise or consists of the cell supernatant indicated in step c) above. It is further noted that, as reflected in table 1 below, in the cell supernatant indicated in step c) above, at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs (that is, pseudo-enveloped particles). Table 1. Percentage of the different type of particles (pseudo-enveloped, intermediates with densities in between and naked) in the supernatants (SN) and in cell extracts obtained by three cycles of freeze-thawing detected in three different stocks of the L0 and HP strains. In SN the most abundant type of particle is the pseudo-enveloped (eL0 and e HP) in levels over 90% in both strains. In freeze-thawed cell extracts, the pseudo- enveloped particles are greatly reduced, particularly in the case of the L0 strain, in favour of an increase of the naked particles (nL0 and nHP) and a third type of structure corresponding to broken pseudo-enveloped particles with an intermediate density in idoxanol gradients. Different letters depict statiscal differences (p<0.05). The eHP particles are more resistant to lysis by freeze-thawing. Thus, in a preferred embodiment of the first aspect of the invention, at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs (pseudo-enveloped particles). It is noted that for the determination of this percentage, the methodology followed is based on separating the different types of particles in iodixanol gradients and quantifying the genomes in each band of the gradient. The naked particles have a density of 1.20 – 1.25 g / cm3and the quasi-enveloped ones have a density of 1.06 – 1.12 g / cm3. The intermediate particles that come from degradation show an intermediate density of between 1.15-1.18 g / cm3. The sample is centrifuged in an iodixanol gradient and different fractions are separated, the density of each of these fractions is determined and the genomes present in each band are quantified. Therefore, in an embodiment, determination of the percentage of the different type of particles (pseudo-enveloped, intermediates with densities in between and naked) is determined in fractions from ultracentrifuged infected cell culture supernatants in iodixanol gradients. It is important to note that the quasi-enveloped particles of the invention (Extracellular Vesicles (EVs) loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids) have a density of 1.06 – 1.12 g / cm3. It is noted that in the present invention, the virus stocks used to produce the composition of the invention are not produced by releasing the viruses from the harvested cells by freeze-thawing, such as by carrying out at least three cycles of freeze-thawing. This is because such procedure would not produce the degree of purity indicated in the above paragraph. It is noted that preferably, the composition, preferably the vaccine composition, comprises the cell supernatant in accordance with step c). Such cell supernatant comprises the EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids (pseudo-enveloped particles) or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides. It is noted that the hepatovirus (human hepatitis A virus (HAV)) viral capsids loaded in the EVs are inactivated particles. Inactivation of these particles can be achieved by any method well known to the skilled artisan. It is noted that the term “EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides”, as used herein, refers to hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides having an EV envelope covering it, such as EV covering the protective protein capsid in the case of viral capsids. The envelopes are thus EVs such as exosomes. In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, the hepatovirus (human hepatitis A virus (HAV)) viral capsids loaded in the EVs are inactivated particles. Inactivation of these particles can be achieved by any method well known to the skilled artisan. In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, said cell line is selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial). Preferably, said cell line is the FRhK-4 cell line or Vero cells. In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, the culturing step of step b) of the cell line to provide the culture supernatant is carried out by growing the cells in a cell medium possibly supplemented with serum, more preferably with foetal calf serum. However, preferably, the culturing step of step b) of the cell line (preferably in the case of Vero cells) to provide the culture supernatant is carried out by growing the cells in a cell medium not supplemented with serum. In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, the Extracellular Vesicles (EVs) loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides are exosomes loaded with viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides. In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, the hepatovirus is the human hepatitis A virus (HAV). In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, the genetic element of interest is selected from the group consisting of any DNA, RNA or polynucleotide analogues thereof encoding a member selected from the group consisting of proteins or fragments of proteins of at least a hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptide. Preferably, the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. More preferably, the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1, and the cell line is selected from FRhK-4 or Vero cells. Still more preferably, the genetic element of interest encodes an immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1; the cell line is selected from FRhK-4 or Vero cells; and the EVs are exosomes. In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, the cell line is infected with a hepatovirus, preferably with the HM175-HP strain (HP). Preferably, the cell line is infected with the HM175-HP strain and the protein shell of the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. More preferably, the cell line is infected with the HM175-HP strain, the protein shell of the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647); and the cell line is selected from FRhK-4 or Vero cells. Still more preferably, the cell line is infected with the HM175-HP strain, the protein shell of the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. Preferably, said viral capsids are inactivated. In a preferred embodiment of the first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the invention, the cell line is infected with a hepatovirus that provides a culture supernatant comprising EVs loaded with viral capsids having a protein shell having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. More preferably, the cell line is infected with a hepatovirus that provides a culture supernatant comprising EVs loaded with viral capsids having a protein shell having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1, and the cell line is selected from FRhK- 4 or Vero cells. Still more preferably, the cell line is infected with a hepatovirus that provides a culture supernatant comprising EVs loaded with viral capsids having a protein shell having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1, the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. According to the invention, the composition of the first aspect or of any of its preferred embodiments, preferably the vaccine composition, does not comprise any adjuvants other than the loaded EVs as such. According to the invention, the EVs in the composition may be loaded with a single hepatovirus viral capsid or hepatovirus antigenic polypeptide or with a combination of two or more hepatovirus viral capsids or hepatovirus antigenic polypeptides. The present invention makes use of extracellular vesicles which have a diameter in the range of from 20 to 500 nm, preferably from 100 to 400 nm, more preferably in the range of from 200 to 300 nm. As already mentioned, the EVs that are used in the present invention are preferably derived from one or more cell lines selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial). Preferably, said cell line is the FRhK-4 cell line or Vero cells. As used herein “Vero cells” shall be understood as a continuous cell line derived from African green monkey kidney epithelial cells (ATCC CCL-81 and ATCC CCL-81.5). These cells are usually used for bioproduction, including hepatitis A virus vaccine production. As used herein “FRhK-4 cells” shall be understood as a continuous cell line derived from Fetal Rhesus monkey kidney epithelial-like cells (ATCC CRL-1688). These cells are usually used for hepatitis A virus replication. As used herein “MRC-5 cells” shall be understood as a human diploid cell line derived from lung fibroblasts (ATCC CCL-171). It is widely used for the production of vaccines, including hepatitis A and poliovirus. The scope of the invention includes both compositions containing EVs derived from a single cell line and compositions containing EVs derived from a plurality of cell lines. It is noted that the composition of the invention can comprise purified EVs or the culture supernatant. Suitable purification techniques of EVs include, but are not limited to, ultracentrifugation, filtration and tangential flow filtration. The selection of the most suitable method to be used for the purification of the EVs falls within the knowledge and skills of the ordinary person of skill in the art. SEQ ID NO 1: MNMSRQGIFQTVGSGLDHILSLADIEEEQMIQSVDRTAVTGASY FTSVDQSSVHTAEVGSHQVEPLRTSVDKPGSKRTQGEKFFLIHSADWLTTHALFHEVA KLDVVKLLYNEQFAVQGLLRYHTYARFGIEIQVQINPTPFQQGGLICAMVPGDQGYGS IASLTVYPHGLLNCNINNVVRIKVPFIYTRGAYHFKDPQYPVWELTIRVWSELNIGTG TSAYTSLNVLARFTDLELHGLTPLSTQMMRNEFRVSTTANVVNLSNYEDARAKMSFAL DQEDWKSDPSQGGGIKITHFTTWTSIPTLAAQFPFNASASVGQQIKVIPVDPYFFQMT NKNPDQKCITALASICQMFCFWRGDLVFDFQVFPTKYHSGRLLFCFVPGNELIDVSGI TLKQATTAPCAVMDITGVQSTLRFRVPWISDTPYRVNRYTKSAHQKGEYTAIGKLIVY CYNRLTSPSNVASHVRVNVYLSAINLECFAPLYHAMDVTTQVGDDSGGFSTTVSTEQN VPDPQVGITTMKDLKGKANRGKMDVSGVQAPVGAITTIEDPVLAKKVPETFPELKPGE SRHTSDHMSIYKFMGRSHFLCTFTFNSNNKEYTFPITLSSTSNPPHGFPSTLRWFFNL FQLYRGPLDLTIVITGATDVDGMAWFTPVGLAVDTPWVEKESALSIDYKTALGAVRFN TRRTGSIQIRLPWYSYLYAVSGALDGLGDKTDSTFGLVSIQIANYNHSDEYLSFSCYL SVTEQSEFYFPRAPLNSNAMLSTESMVSRIAAGDLESSVDDPRSEEDKRFESHIECRK PYKELRLEVGKQRLKYAQEELSNEVLPPPRKMKGLFSQAKISLFYTEEHEMMKFSWRG VTADTRALRRFGFSLAAGRSVWTLEMDAGVLTGRLIRLNDEKWTEMKDDKIVSLIEKF TSNKYWSTVNFPHGMLDLEEIAANSKDFPNMSETDLCFLLHWLNPKKINLADRMLGLS GVQEIKEQGVGLIAECRTFLHSIAGTLKSMMFGFHQSVTVEIINTVLCFVKSGILLYV IQQLNQDEHSHIIGLLRVMNYVDIGCSVISCGKVFSKMLETVFNWQMDSRMMELRTQS FSNWLRDICSGITIFKNFKDGICWLYTKLKDFYEVNYGKKKDILNILKDNQQRIEKAI EEADKFCILQIQDVEKSEQYQKGVDLIQKLRTVYSMAQVDPNLMVHLLPLRDCIARVH QKLKNLGCINQAMVTRCEPVVCYLHGKRGGGKSLTSIALATKICKHYGVEPEKNIYTK PVASDYWDGYSGQLVCIIDDIGQNTTDEDWSDFCQLVSGCPMRLNMASLEEKGRHFSS PFIIATSNWSNPSPKTVYVKEAIDRRLHFKVEVKPASFFKNPHNDMLNVNLAKTNDAI KDMSCVDLIMDGHNVSLMDLLSSLVMTVDIRKQNMTEFMELWSQGISDDNDSAVAEFF QSFPSGEPSNSKLSGFFQSVTNHKWVAVGAAVGILGVLVGGWVVYKHFSHKEEEPIPS EGVYHGVTKPKHVIKLDADPVESQSTLEVAGLVRKNLVQFGVGEKNGCVRWVMNALGV KDDWLLVPSHAYKFEKDYEMMEFYFNRGGTYYSISAGNVVIQSLDVGFQDVVLMKVPT IPKFRDITQHFIKQGDVPRALNRLATLVTTVNGTPMLISEGPLKMEEKATYVHKKNDG TTVDLAVDQAWRGKGEGLPGMCGGALVSSNQSIQNAILGIHVAGGNSILVAKLVTQEM FQNIDKKIESQRIMKVEFTQCSMNVVSKTLFRKSPIYHHIDKTMINFPAVMPFSKAEI DPMAVMLSKYSLPIVEEPEGYKEASIFYQNKIVGKTQLVDDFLDLDMAITGAPGIDAI NMDSSPGFPYVQEKLTKRDLIWLDENGLLLGVHPRLAQRISFNTVMMENCSDLDVVFT TCPKDELRPLEKVLESKTRAIDACPLDYTILCRMYWGPAISYFHLNPGFHTGVAIGID PDKQWDELFKTMIRFGDVGLDLDFSAFDASLSPFMIREAGRIMSELSGTPSHFGTALI NTIIYSKHLLYNCCYHVCGSMPSGSPCTALLNSIINNVNLYYVFSKIFGKSPVFFCQA LKILCYGDDVLIVFSRDVQIDNLDLIGQKIVDEFKKLGMTATSADKNVPQLKPVSELT FLKRSFNLVEDRIRPAISEKTIWSLIAWQRSNAEFEQNLENAQWFAFMHGYEFYQKFY YFVQSCLEKEMIEYRLKSYDWWRMRFYDQCFICDLS An alternative first aspect of the invention refers to a composition, preferably a vaccine composition, comprising naturally occurring EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides, capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A. In a preferred embodiment of the alternative first aspect of the invention, the hepatovirus (human hepatitis A virus (HAV)) viral capsids loaded in the EVs are inactivated particles. Inactivation of these particles can be achieved by any method well known to the skilled artisan. It is noted again noted that the above-mentioned composition can comprise or consists of a cell supernatant. It is further noted that at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition of the alternative first aspect of the invention are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs (that is, pseudo-enveloped particles). In a preferred embodiment of the alternative first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the alternative first aspect of the invention, the Extracellular Vesicles (EVs) loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides are exosomes loaded with said viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides. In a preferred embodiment of the alternative first aspect of the invention, optionally in combination with any previous or subsequent embodiment of the alternative first aspect of the invention, the protein shell of the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. More preferably, the protein shell of the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647). Still more preferably, the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) and the EVs are exosomes. Preferably, said viral capsids are inactivated. Still more preferably, said EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids are comprised in a culture supernatant. It is noted that, in this aspect of the invention, preferably the naturally occurring EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids are produced by using any of the above-mentioned cell lines and infecting them with a hepatovirus, preferably with the HM175-HP strain (HP). Preferably, the cell line is infected with the HM175-HP strain and the protein shell of the viral capsid loaded in the EVs is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647). More preferably, the cell line is infected with the HM175-HP strain, the protein shell of the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) and the infected cell line is selected from FRhK-4 or Vero cells. Still more preferably, the cell line is infected with the HM175-HP strain, the protein shell of the viral capsid is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. It is further noted that the hepatitis A virus (HAV) strain (HP strain) of the invention, characterized by having a fast-growing phenotype combined with an increased release of quasi-enveloped particles into the supernatant thanks to the S134G replacement in the VP2 protein, which is exclusive of the HP human strain, can be obtained or produced as indicated in Example 1. As used herein, naturally occurring EVs are extracellular vesicles which have not been modified in vitro to express a heterologous component by loading a nucleic acid molecule exogenous to the vesicles’ donor cells. That is, those EVs loaded with viral capsids preferably obtained by a method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides; b. infecting said cell line with a hepatovirus and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids; and c. recovering, isolating or purifying the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides or the supernatant comprising the same. A further alternative first aspect of the invention, refers to composition, preferably a vaccine composition, comprising engineered EVs loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides, capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A. It is further noted that at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition of this further alternative first aspect of the invention are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs (that is, pseudo- enveloped particles). In a preferred embodiment of the further alternative first aspect of the invention, the Extracellular Vesicles (EVs) loaded with hepatovirus (human hepatitis A virus (HAV)) viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides are exosomes loaded with said viral capsids or hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptides. In another preferred embodiment of the further alternative first aspect of the invention, the hepatovirus (human hepatitis A virus (HAV)) antigenic polypeptide is the immunogenic sequence of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. Preferably, the hepatovirus antigenic polypeptide is an immunogenic sequence of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1, and the EVs are exosomes. As used herein, the term “engineered EVs” refers to extracellular vesicles which have been modified in vitro to express a heterologous component by loading a nucleic acid molecule exogenous to the vesicles’ donor cells. It is therefore to be intended that an engineered EV is a non-naturally occurring vesicle. The loading of exogenous nucleic acid molecules into the EVs according to the present invention may be accomplished by a number of different techniques known in the art, including, for example, electroporation, sonication, lipofectamine mediation, microinjection, co-incubation, or dialysis. A second aspect of the invention refers to a method for producing a composition comprising EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, the method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides; b. infecting said cell line with a hepatovirus or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids or hepatovirus antigenic polypeptides; and c. recovering, isolating, and / or purifying the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, or the cell supernatant comprising the same; wherein preferably at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs. It is noted that in the present invention, the virus stocks used to produce the composition are not produced by releasing the viruses from the harvested cells by freeze-thawing, such as by carrying out at least three cycles of freeze-thawing. This is because such procedure would not produced the degree of purity indicated in the above paragraph. In a preferred embodiment of the second aspect of the invention, the cell line is infected with a hepatovirus, and wherein more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of the hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs, and wherein preferably the method comprises an inactivation step of the hepatovirus viral capsids. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the said cell line is selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably, FRhK-4 cells or Vero cells. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the culturing step of the cell line to provide the culture supernatant is carried out by growing the cells, preferably Vero cells, in a cell medium in the absence of serum. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are exosomes. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the hepatovirus is the human hepatitis A virus (HAV). In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the genetic element of interest is selected from the group consisting of any DNA, RNA or polynucleotide analogues thereof encoding a member selected from the group consisting of proteins or fragments of proteins of at least a hepatovirus antigenic polypeptide. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the EVs are naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting a cell line selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably FRhK-4 cells or Vero cells, with the HM175-HP strain (HP), wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. In another preferred embodiment of the second aspect of the invention, optionally in combination with any of the previous or subsequent embodiments of the second aspect of the invention, the protein shell of the viral capsid is of SEQ ID NO 1, the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. A third aspect of the invention refers to a composition comprising EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides obtained by the method of the second aspect of the invention or of any of its preferred embodiments. In the context of the present invention, the composition of the invention (as defined in any of the previous aspects of the invention (first or third aspects) may be used as a vaccine for the treatment of an existing disease or prophylactically to prevent the occurrence of this disease. Therefore, in a fourth aspect of the invention refers to the composition of the first aspect or of the alternative first aspect or of the further alternative first aspect of the invention or of the third aspect of the invention, for use in generating an immunogenic immune response, preferably a protective immunogenic immune response, against a hepatovirus in a subject in need thereof, preferably in a human subject. Preferably, wherein the hepatovirus is HAV. More preferably, wherein the subject is a human subject. Accordingly, the composition of the present invention is particularly useful for the treatment or prophylaxis of infectious diseases, in particular of hepatitis A. The composition according to the invention may be used alone or in combination with other vaccines. In one embodiment, the composition according to the invention further comprises one or more polycationic substances, said one or more polycationic substances being associated with the outer lipid layer of the lipid bilayer membrane of the EVs through electrostatic interactions. Preferably, the one or more polycationic substances are selected from the group consisting of cationic proteins, including protamine, calcitonin peptides, plectasin, lactoferrin, protamine-like proteins, such as spermine or spermidine, nucleoline, histones, cell penetrating peptides (CPPs); cationic peptides, including histidine-rich peptides, arginine- rich peptides, lysine-rich peptides, cationic arginine-rich peptides (CARPs); polypeptides, including poly-arginine, poly-lysine, poly-histidine, histidine- rich peptides, arginine-rich peptides, lysine-rich peptides; polysaccharides, including chitosan, glycosaminoglycan such as polysulfated glycosaminoglycan (PSGAG), cationic dextrans; glycerol, polyethylene glycol (PEG). Before usage, the EVs in the composition of the invention may be lyophilized and resuspended with water. Alternatively, the EVs used in the composition of the invention may be freshly prepared or stored at 4°C, -20°C or - 80°C. The composition according to the present invention may be formulated in several administrable forms, including powders, granules, tablets, capsules, suspensions, emulsions, syrups, aerosols, pills, sugar-coated tablets, capsules, liquids, gels, syrups, slurries, and suspensions. The composition of the invention may optionally contain suitable excipients, preservatives, solvents or diluents according to conventional method. Exemplary excipients include, but are not limited to, sugars, including sucrose, D- mannose, D-fructose, dextrose, anhydrous lactose, D-trehalose, D-sorbitol; proteins, including human serum albumin, hydrolyzed casein, MRC-5 cellular proteins, hydrolyzed gelatin, CRM 197 carrier protein, proteins from plants, yeast, bacteria, eggs; essential and non-essential aminoacids such as asparagine, phenylalanine, arginine, histidine; sodium, including sodium chloride, sodium bicarbonate, sodium carbonate, sodium borate, sodium benzoate, sodium taurodeoxycholate, sodium deoxycholate, monobasic sodium phosphate, dibasic sodium phosphate, sodium metabisulphite; potassium, including potassium phosphate, polacrilin potassium, monobasic and dibasic potassium phosphate, potassium chloride; magnesium stearate, calcium chloride, calcium phosphate, calcium silicate, glutamate, cellulose, microcrystalline cellulose, cellulose acetate phthalate, aluminum, aluminum hydroxide, aluminum phosphate, amorphous aluminum hydroxyphosphate sulfate, potassium aluminum sulfate, citric acid, iron ammonium citrate, castor oil, neomycin, streptomycin, aminoglycoside, kanamycin, gentamicin, chlortetracycline, amphotericin B, plasdone C, alcohol, acetone, benzethonium chloride, formaldehyde, glycerin, ascorbic acid, trometamol, urea, glutaraldehyde, 2-phenoxyethanol, polysorbate 80 (Tween 80), polymyxin B, ammonium thiocyanate, tromethamine, host cell DNA benzonase, formalin, phosphate-buffered saline solution, polysorbate 20, deoxycholate, dibasic dodecahydrate, monobasic dehydrate, formalin, polymyxin B, beta-propiolactone, hydrocortisone, squalene, sorbitan trioleate, barium, cetyltrimethylammonium bromide (CT AB), octoxynol-10 (TRITON X- 100), a- tocopheryl hydrogen succinate, cetyl trimethlyammonium bromide, and P - propiolactone, thimerosal, ethylenediaminetetraacetic acid (EDTA), phenol, beta- propiolactone, DMEM, HEPES, polydimethylsiloxane, vitamins, dioleoyl phosphatidylcholine (DOPC), 3-O-desacl-4’monophosphoryl lipid A (MPL), lipids, cholesterol, panthenol, gums, including guar gum, boric acid and borates, including sodium tetraborate, glycerol, allantoin, triethanolamine, alginate, pluronic, poloxamer, including P188, P331; PEG, including PEG8000; glycols, including ethylene glycol, propylene glycol, and glycerol; citicoline (cyti-dine-5-diphosphocholine; CDP-choline), cholesterol. Illustrative, non-limiting examples of preservatives suitable for use in the composition of the invention include parabens, including ethyl paraben, methyl paraben, propyl paraben, formaldehyde donors including DMDM hydantoin, imidazolidinyl urea, and glutaraldehyde, phenol derivatives, benzoic acid, benzyl alcohol. Suitable solvents or diluents to be used in the invention may be selected from purified water, ethanol and benzyl alcohol. As already indicated, the composition of the invention may optionally contain suitable excipients, preservatives, solvents or diluents according to conventional method but not necessarily adjuvants, as the composition of the invention does not require the presence of an adjuvant. Nonetheless, in an embodiment, it is contemplated that an adjuvant can be added to the composition for use as a vaccine. Illustrative, non-limiting examples of adjuvants suitable for use in the immunogenic composition of the invention are mineral compositions, including aluminum salts such as aluminium hydroxide, aluminium potassium phosphate, AS04, and others, calcium salts, hydroxides (e.g. oxyhydroxides), phosphates (e.g. hydroxyphoshpates, orthophosphates), sulphates; emulsions, including oil-in-water and water-in-oil emulsions, such as Freund’s adjuvant, complete Freund’s adjuvant, incomplete Freund’s adjuvant, MF59, AF03, AS03, AS02, glucopyranoside lipid adjuvant (GLA- SE), glucopyranosyl lipid adjuvant (GLA); bacterial or microbial derivatives, including non-toxic derivatives of enterobacterial lipopolysaccharide (LPS), monophosphoryl lipid A (MPL), 3-O-deacylated MPL (3dMPL), lipid A, lipid A from Escherichia coli such as OM-174. OM-174; immunostimulatory oligonucleotides, including nucleotide sequences containing a CpG motif, bacterial double stranded RNA, oligonucleotides containing palindromic or poly(dG) sequences, ADP- ribosylaling toxins and detoxified derivatives, RC529; cyclic GMP-AMP adjuvant, STING agonists, CAF01, immuno stimulating complexes (ISCOMs), ISCOMATRIX, AS01; polyoxyethylene ether and polyoxyethylene ester formulations, polymeric particles, such as poly(lactide-co- glycolide) (PLG) microparticles, polyphosphazene (PCPP), saponin formulations, such as saponin derived from Smilax ornata (sarsaprilla), Gypsophilla paniculata (brides veil), and Saponaria officinalis (soap root), purified formulations, such as QS7, QS17, QS18, QS21, QH-A, QH-B and QH-C; human immunomodulators, including cytokines, such as interleukins (e.g. IL-1, IL-2, IL-4, IL-5, IL-6, IL-7, IL- 12, etc.), interferons (e.g. interferon-y), macrophage colony stimulating factor, and tumor necrosis factor; bioadhesives and mucoadhesives, including esterified hyaluronic acid microspheres, or mucoadhesives such as cross-linked derivatives of poly(acrylic acid), polyvinyl alcohol, polyvinyl pyrollidone, polysaccharides and carboxymethylcellulose, chitosan and derivatives thereof; muramyl peptides, including N-acetyl-muramyl-Lthreonyl-D- isoglutamine (thr-MDP), N-acetyl-normuramyl-L-alanyl-D-isoglutamine (nor-MDP), and N-acetylmuramyl-Lalanyl-D-isoglutaminyl-L-alanine-2-(l’-2’-dipalmitoyl-sn- glycero-3- hydroxyphosphoryloxy)-ethylamine MTP-PE); imidazoquinolone compounds, including Imiquamod and its homologues; virosomes and Virus Like Particles (VLPs). The composition of the invention may be administered via various routes, including oral, intranasal, parenteral, including subcutaneous, intraperitoneal, intravenous, intradermal, intramuscular, intrasplenic, and intranodal. Preferably, the pharmaceutical composition of the present invention is in a form suitable for oral, intranasal or parenteral administration. The administration dose, the number and frequency of applications are determined according to various factors, such as the patient's characteristics, and can be determined by a person of ordinary skill in the art by using his / her normal knowledge. In addition, the composition according to the invention may be lyophilized and is stable without the need of a cold-chain storage. The following experimental section is provided purely by way of illustration and is not intended to limit the scope of the invention as defined in the appended claims. In the following experimental section, reference is made to the appended drawings. Example 1. Supernatant yields of quasi-enveloped particles of the HP strain Methods In this example a hepatitis A virus (HAV) strain (HP strain) with a fast-growing phenotype combined with an increased release of quasi-enveloped particles into the supernatant, thanks to its exclusive S134G replacement in the VP2 protein, which allows a more efficient interaction with the cellular protein ALIX, was used to infect Vero, MRC-5 and FRhK-4 cells. Comparative studies were carried out with the HM175- 43c strain (L0 strain). One-step growth curves were performed for the HP and L0 strains in Vero (ATCC CCL- 81), MRC-5 (ATCC CCL-171) and FRhK-4 (ATCC CRL-1688) cells grown under different conditions. In the presence of fetal calf sera (FCS), a multiplicity of infection (MOI) of 0.1 was used in MRC-5 and FRhK-4 cells and a MOI of 5 in Vero cells due to its lower permisssiveness. In a second round of experiments, both strains were adapted to replicate in Vero cells adapted to grow in the absence of FCS (ATCC CCL-81.5). A one step growth curve using a MOI of 0.05 was performed. In all cases, the yield of viruses in the supernatant of infected cells was assessed. It is noted that the hepatitis A virus (HAV) strain (HP strain) with a fast-growing phenotype combined with an increased release of quasi-enveloped particles into the supernatant, associated with its exclusive S134G replacement in the VP2 protein, which favors its interaction with the cellular protein ALIX, used to infect Vero, MRC-5 and FRhK-4 cells, can be obtained or produced by a process comprising the steps of: i) Synthesis of a cDNA based on the sequence GenBank KX088647; ii) cloning the cDNA into a transcription vector under the control of the SP6 or T7 promoters; iii) in vitro transcription of the cloned cDNA into an mRNA using the SP6 or T7 RNA polymerases; iv) transfection of FRhK-4 cells; v) Purification of HP infectious viruses; and vi) Growth of the HP viruses in FRhK-4 cells in the presence of 0.05 mg / ml Actynomicin D. That is, a synthetic cDNA from the sequence GenBank KX088647 can be cloned under a transcription vector, usually using the SP6 or T7 promoter, to obtain an infectious mRNA through in vitro transcription. This mRNA can be transfected into FRhK-4 cells to obtain the infectious HP strain. This strain has three mutations in the IRES and several mutations in the capsid coding region which increases the IRES activity and optimizes the codon usage, respectively. The addition of Actynomicin D is required to get the epistatic effect of these mutations. Sequence GenBank KX088647 can be obtained from Hepatovirus A isolate HM175- HP polyprotein gene, complete cds - Nucleotide - NCBI (nih.gov) ( https: / / www.ncbi.nlm.nih.gov / nuccore / KX088647), in particular this sequence corresponds with SEQ ID NO 2: 1 gtccctcttg gaagtccatg gtgaggggac ttgatacctc accgccgttt gcctaggcta 61 taggctaaat tttccctttc ccttttccct ttcctattcc ctttgttttg tttgtaaatg 121 ttgatttgta aatattgatt cctgcaggtt cagggttctt aaatctgttt ctctataaga 181 acactcattt cacgctttct gtcttctttc ttccagggct ctccccttgc cctaggctct 241 ggccgttgcg cccggcgggg tcaactccat gattagcatg gagctgtagg agtctaaatt 301 ggggacacag atgtttggaa cgtcaccttg cagtgttaac tcggctttca tgaatctctt 361 tgatcttcca caaggggtag gctacgggtg aaacctctta ggctaatact tctatgaaga 421 gatgccttgg atagggtaac agcggcggat attggtgagt tgttaagaca aaaaccattc 481 aacgccggag gactgactct catccagtgg atgcattgag tggattgact gtcggggctg 541 tctttaggct taattccaga cctctctgtg ctcggggcaa acatcatttg gccttaaatg 601 ggattctgtg agaggggatc cctccattga cagctggact gttctttggg gccttatgtg 661 gtgtttgccg ctgaggtact caggggcatt taggtttttc ctcattctca aataataatg 721 aacatgtcta gacaaggtat tttccagact gttgggagtg gtcttgacca catcctgtct 781 ttggcagaca ttgaggaaga gcaaatgatt caatcagttg ataggactgc agtgactggt 841 gcttcttatt ttacttctgt ggatcaatct tcagttcata cagctgaggt tggatcacac 901 caggttgaac ctttgagaac ctctgttgat aaacccggtt caaagaggac tcagggagag 961 aaatttttct tgattcattc tgcagattgg cttactacac atgctctttt ccatgaagtt 1021 gcaaaattgg atgtggtgaa attattatac aatgagcagt ttgctgttca agggttgttg 1081 agataccata catatgcaag atttggcatt gaaattcaag ttcagataaa ccctacacct 1141 ttccaacagg ggggattgat ctgtgctatg gttcctggtg accagggcta tggttctata 1201 gcatcattga ctgtttatcc tcatggtttg ttaaattgca atattaacaa tgtggttaga 1261 ataaaggttc catttattta cacaagaggt gcttaccact ttaaagatcc acaataccca 1321 gtttgggaat tgacaattag agtttggtca gaattaaata ttgggacagg aacttcagct 1381 tatacttcac tcaatgtttt agctagattt acagatttgg agttgcatgg attaactcct 1441 ctttctacac aaatgatgag aaatgaattt agggtcagta ctactgcgaa tgtggtgaat 1501 ctgtcaaatt atgaagatgc aagagcaaag atgtcttttg ctttggatca ggaagattgg 1561 aaatctgatc cgtcccaggg tggtgggatc aaaattactc attttactac ttggacatct 1621 attccaactt tggctgctca gtttccattt aatgcttcag cctcagttgg tcaacaaatt 1681 aaagttattc cagttgaccc atattttttc caaatgacaa ataaaaatcc tgaccaaaaa 1741 tgtataactg ctttggcttc tatttgtcaa atgttttgtt tttggagagg tgatcttgtc 1801 tttgattttc aagtttttcc caccaaatat cattcaggta gattactgtt ttgttttgtt 1861 cctggcaatg agctaataga tgtttctgga atcacattaa agcaagcaac tactgctcct 1921 tgtgcagtaa tggatattac aggagtgcag tcaactttga gatttcgtgt tccctggatt 1981 tctgacactc cttacagagt gaacaggtat acaaagtcag cacatcagaa aggtgagtac 2041 actgccattg ggaagcttat tgtgtattgt tataacagat tgacctctcc ttctaacgtt 2101 gcttcccatg tcagagtgaa tgtttatctt tcagcaatta acttggaatg ttttgctcct 2161 ctttatcatg ctatggatgt tactacacaa gttggagatg attctggagg tttttcaaca 2221 acagtttcta cagaacagaa tgttccagat ccccaagttg gtataacaac catgaaagat 2281 ttgaaaggaa aagctaacag agggaaaatg gatgtttcag gagtacaagc acctgtggga 2341 gctatcacaa caattgagga tccagttcta gcaaagaaag tacctgagac atttcctgaa 2401 ttgaaacctg gagaatccag acatacatca gatcatatgt ccatctacaa gtttatggga 2461 aggtctcatt tcttgtgcac ttttacattc aattcaaata ataaagagta cacatttcct 2521 ataaccttgt cttcaacctc taatcctcct catggtttcc catcaacact gaggtggttt 2581 ttcaacttgt ttcagttgta tagagggcct ttagatctga caattgttat tacaggagca 2641 actgatgtag atggcatggc ctggttcact ccagtaggtc ttgccgttga tactccttgg 2701 gtagagaagg agtcagcttt gtctattgac tacaaaactg ctcttggagc tgtcagattt 2761 aacacaagga gaacagggag cattcagatt agattaccat ggtattctta tttatatgct 2821 gtgtctggag cactggatgg tttgggagac aagacagatt ctacatttgg attggtttct 2881 attcagattg caaattacaa tcattctgat gaatacttgt cttttagttg ttatttgtct 2941 gtcacagaac aatcagagtt ttattttccc agagctccat tgaactcaaa tgccatgtta 3001 tccactgagt caatggtgag cagaattgca gctggagact tggagtcatc agtggatgat 3061 cctagatcag aggaagataa aagatttgag agtcatatag aatgcaggaa gccatataaa 3121 gaactgagat tagaagttgg gaaacaaaga ctcaagtatg ctcaggaaga attgtcaaat 3181 gaagtacttc caccccctag gaaaatgaag ggactgtttt cacaagccaa aatttctctt 3241 ttttatactg aggagcatga aatgatgaag ttttcctgga gaggtgtgac tgctgatact 3301 agagctttaa ggaggtttgg attctctttg gccgcaggca gaagtgtgtg gactcttgaa 3361 atggatgctg gggttcttac tgggagactg attagactga atgatgagaa atggacagaa 3421 atgaaggatg acaagattgt ttcattgatt gaaaagttta caagtaacaa atattggtcc 3481 acagtgaatt tcccacatgg gatgttggat cttgaagaaa ttgctgccaa ttctaaggat 3541 tttcctaaca tgtctgaaac ggatttgtgt ttcttgctgc attggttaaa tccaaagaaa 3601 attaatttag cagatagaat gcttggattg tctggagttc aggaaattaa agaacaaggt 3661 gttggattaa tagcagagtg tagaactttc ttacattcta ttgctggaac tttaaaatct 3721 atgatgtttg gatttcatca atctgtgact gttgaaatta taaacactgt gctctgtttt 3781 gttaagagtg gaattttgct ttatgtaata caacaattga atcaggatga acattctcac 3841 ataattggtc tgttgagagt catgaattat gtagatattg gttgttcagt tatttcatgt 3901 ggcaaagttt tttccaaaat gctggaaaca gtctttaatt ggcaaatgga ctccagaatg 3961 atggagttaa ggactcagag tttttccaac tggttaagag atatttgttc tgggatcacc 4021 atttttaaaa acttcaagga tggaatttgt tggctttata caaaattaaa ggacttttat 4081 gaagtgaatt atggcaagaa gaaggacatt ttaaatattc ttaaagataa ccaacaaaga 4141 atagagaaag ccattgagga agccgataaa ttttgcattt tgcaaatcca agatgtggaa 4201 aaatctgaac agtatcagaa aggggttgac ttgatacaaa aattgagaac tgtttattca 4261 atggctcagg ttgatccaaa tttaatggtt catttgttac ctttgagaga ttgtatagca 4321 agagttcatc agaaacttaa aaaccttgga tgtataaatc aggcaatggt aacgagatgt 4381 gagccagttg tctgttattt acatggcaaa agagggggag gaaagagctt aacatcaatt 4441 gcattggcaa ccaaaatttg taaacattat ggtgttgagc ctgaaaagaa tatctatact 4501 aaacctgtgg cttcagatta ctgggatgga tatagtggac aattagtttg catcattgat 4561 gatattggcc aaaacacaac agatgaggac tggtcagatt tttgtcagtt agtgtcagga 4621 tgtccaatga gattaaacat ggcctctctt gaggagaagg gtaggcattt ttcttctcct 4681 tttataatag caacttcaaa ttggtcaaat ccaagtccga aaacagttta tgttaaggaa 4741 gcaattgacc gcagactcca tttcaaggtt gaagttaaac ctgcttcatt tttcaaaaat 4801 cctcacaatg atatgttgaa tgttaattta gctaaaacaa atgatgcaat caaagatatg 4861 tcttgtgttg atttgataat ggatggacat aatgtttcat tgatggattt gcttagttct 4921 ttagtcatga cagttgatat tagaaaacaa aacatgactg aattcatgga gttgtggtct 4981 cagggaattt cagatgataa tgatagtgca gtagctgagt ttttccagtc ttttccatct 5041 ggtgaaccat cgaactctaa attatctggc tttttccaat ctgttactaa tcacaagtgg 5101 gttgctgtgg gagctgcagt tggcattctt ggagtgctcg ttggaggatg ggttgtgtat 5161 aagcatttct cccacaaaga ggaagaacca atcccatctg aaggggtata tcatggtgta 5221 actaagccca agcatgtgat taaattagat gcagatccag tagaatctca gtcaactttg 5281 gaagtagcag gactggttag gaagaacttg gttcagtttg gagttggaga gaagaatgga 5341 tgtgtgagat gggttatgaa tgccttggga gtgaaagatg attggctgct tgtgccttcc 5401 catgcttata aatttgagaa agattatgaa atgatggagt tttattttaa tagaggtgga 5461 acttactatt caatttcagc tggtaatgtt gttattcaat ctttggatgt gggattccag 5521 gatgttgttc tgatgaaggt tcctacaatt cctaagttta gagatattac tcagcatttt 5581 attaagcaag gggatgtgcc tagagctttg aatcgcctgg caacattagt gacaactgta 5641 aatggaaccc ctatgttaat ttctgagggc ccactaaaga tggaagagaa agctacttat 5701 gttcataaga aaaatgatgg tacaacagtt gatttagctg tggatcaggc atggagagga 5761 aaaggcgaag gtcttcctgg aatgtgtggt ggggccttgg tttcatcgaa tcaatctata 5821 cagaatgcaa tcttgggcat ccatgttgct ggaggaaatt caattcttgt tgcaaaattg 5881 gttactcaag aaatgttcca aaatattgat aagaaaattg aaagtcagag aattatgaaa 5941 gtggagttta ctcagtgttc aatgaatgtg gtctccaaaa cgctttttag aaagagtccc 6001 atttatcatc acattgataa aaccatgatt aattttcctg cagttatgcc tttttctaaa 6061 gctgaaattg atccaatggc tgtgatgtta tctaagtatt cattacctat tgtagaagaa 6121 ccagagggtt ataaagaggc ttcaattttt tatcaaaata aaatagtggg taagactcag 6181 ttagttgatg attttctaga tcttgatatg gccattacag gagccccagg aattgatgct 6241 atcaacatgg attcatctcc tggatttcct tatgtccagg agaagttgac caaaagagat 6301 ttaatttggt tggatgaaaa tggtttattg ctgggagttc atccaagatt ggctcagaga 6361 atctcattca atactgtcat gatggaaaat tgttctgatt tggatgttgt ttttacaacc 6421 tgtccaaaag atgaattgag accattagag aaagtgttgg aatcaaaaac aagagctatt 6481 gatgcttgtc ctctggatta cacaattttg tgccgaatgt attggggtcc agctattagt 6541 tattttcatt tgaatccagg tttccataca ggtgttgcta ttggcataga tcctgataaa 6601 cagtgggatg aactatttaa aacaatgata agattcggag atgttggtct tgatttagat 6661 ttctctgctt ttgatgctag tcttagtcca tttatgatta gagaagcagg tagaatcatg 6721 agtgaactat ctggaactcc atcccatttt ggcacagctc ttatcaatac tatcatttat 6781 tccaagcatt tgctgtataa ctgttgctat catgtttgtg gttcaatgcc ctctgggtct 6841 ccttgtacag ctttgctaaa ttcaattatt aataatgtca atttgtatta tgtgttttcc 6901 aagatatttg gaaagtctcc agttttcttt tgtcaggctt tgaagattct ctgttatgga 6961 gatgatgttt taatagtttt ctctcgagat gttcagattg ataatcttga tttgattgga 7021 caaaaaattg tagatgagtt taagaaactt ggcatgacag ctacttctgc tgacaagaat 7081 gtacctcagc tgaaaccagt ttcggaattg acttttctca aaagatcttt caatttggta 7141 gaggatagaa ttagacctgc aatttcggaa aaaacaattt ggtctttaat agcatggcag 7201 agaagtaacg ctgagtttga gcagaactta gaaaatgctc agtggtttgc ttttatgcat 7261 ggctatgagt tttatcagaa attctattat tttgttcagt cctgtttgga gaaagagatg 7321 atagaataca gacttaaatc ttatgattgg tggagaatga gattttatga ccagtgtttc 7381 atttgtgacc tttcatgatt tgtttaaatg aactttctt Results The supernatant yields of quasi-enveloped particles of the HP strain (eHP) compared with the L0 strain (eL0) were: (i) 1.9X, 2X and 3.4X times higher in Vero, MRC-5 and FRhK-4 cells grown in the presence of fetal calf sera (FCS). In this last model, the release of eHP particles (titer of infectious viruses in the supernatant of the total viruses produced) is 2X higher. (ii) 1000X higher in Vero cells adapted to grow in the absence of FCS and using a multiplicity of infection of 0.05. Part of these results are illustrated in figure 1. Example 2. eHP particles in the absence of an adjuvant. Immunogenicity and vaccination effect. Methods In the immunogenicity studies, 5 X 107inactivated TCID50units of eHP particles in the absence of any adjuvant were subcutaneously inoculated in BALBC mice at days 0, 14, 28 and 42. For comparison, 5 X 107inactivated TCID50 units of nHP particles or 5 X 107inactivated TCID50units of nL0 in combination with Al(OH)3were similarly inoculated. Blood samples were obtained through the caudal vein at days 0, 28, 42 and 56 post-inoculation. Total anti-HAV IgGs, and the ratio of IgG2 / IgG1 were quantified by ELISA. The titre of antibodies neutralizing the L0 (wild type-like) infectivity was obtained infecting FRhK-4 cells. In the vaccination studies, the same schedule was performed in MAVS- / - and IFNR- / - mice, which are a model for HAV infection and pathogenicity, respectively. Two weeks after the last vaccine dose mice were challenged with 108TCID50 HAV infectious units. Negative sense RNA copies, which are intermediates of genome replication were determined in the liver from both mice models (anti-genome RNA), and the number of immune cell infiltrates were quantified in liver samples from the IFNR- / - mice (determined by RTqPCR, and observed on H&E stained liver sections, respectively), and compared with titres in non-vaccinated and similarly challenged animals. Finally, virus shedding in faeces were also titrated (RT-qPCR) and compared between the different vaccine treatments and the non-vaccinated animals. Results 2.1. The eHP particles administered in the absence of any adjuvant are equally immunogenic in BALB / C mice than naked particles (nHP) administered with alumina (Figure 2). Specifically, 2 X 108TCID50 of eHP particles in the absence of any adjuvant induce similar concentrations of total IgG antibodies recognizing the heterologous L0 capsids in a sandwich ELISA than 2 X 108TCID50 of nHP particles. 2.2. eHP particles in the absence of any adjuvant induce equivalent levels of antibodies able to neutralize the L0 strain in vitro than the nHP particles with alumina (Figure 3). Specifically, the average neutralization titre is 102.3450N50U / ml of sera (units able to neutralize 50.000 infectious units in 50% of the replicas in FRhK-4 cells) for eHP particles vs 102.2950N50U / ml of sera for nHP particles with alumina. 2.3. eHP particles, administered in the absence of any adjuvant in BALB / C mice, produce a similar total anti-HAV IgG response, an increase in the anti-HAV IgG2a response and a similar HAV neutralization response compared with a standard vaccine product, i.e. naked L0 particles (nL0) administered with alumina. Specifically, 2 X 108TCID50 units of eHP or nL0 induce: i) equivalent concentrations of IgGs recognizing L0 capsids (average reciprocal serum dilutions of 27.000 vs 36.000, for eHP and nL0 with alumina, respectively, Figure 4), ii) IgG2a / IgG1 ratios 250X higher in eHP (Figure 5), and iii) equivalent levels of neutralizing antibodies (titres of 102.3450N50U / ml vs 102.2150N50U / ml of sera, Figure 6). 2.4. vaccination with eHP particles, in the absence of any adjuvant, provided an increased protection against a challenge of 108HAV infectious units in the MAVS- / - and IFNR- / - mice models compared with vaccination with nHP particles administered with alumina as determined by a lower titre of negative sense RNA copies in the liver (Figure 7). Specifically, eHP vaccination induced a 158X reduction (99%) in MAVS- / - mice and a 3X reduction (67%) in IFNR- / - mice of the HAV negative RNA copies compared with non-vaccinated and similarly challenged animals. In contrast, vaccination with nHP particles plus alumina induces a 38X (97%) and a 1.9X reduction (47%), in both mice models, respectivelyVaccination with the HAVRIX vaccine, which also contains alumina, induces a similar reduction compared to the nHP particles (26X and 96%) in the MAVS- / - mouse model. 2.5. vaccination with eHP particles, in the absence of any adjuvant, provided an increased protection against a challenge of 108HAV infectious units in an IFNR- / - mouse model compared with vaccination with nHP particles administered with alumina as determined by the number of liver immune cell infiltrates (Figure 8). Specifically, vaccination with eHP particles induces a 6.7X reduction (85%) in liver infiltrates compared with non-vaccinated and similarly challenged animals. In contrast, vaccination with nHP particles plus alumina induces a 5X reduction (80%). 2.6. vaccination with eHP particles, in the absence of any adjuvant, provided an increased protection against a challenge of 108HAV infectious units in both the MAVS- / - and IFNR- / - mouse models compared with vaccination with nHP particles administered with alumina as determined by virus shedding in faeces (Figure 9). Specifically, vaccination with eHP particles show a 2.6X reduction (62%), and a 1.9X reduction (46%), respectively in each mouse model, of the virus shedding compared with non-vaccinated, and similarly challenged animals. In contrast, vaccination with nHP particles plus alumina induces a 1.4X reduction (27%) in both models. Vaccination with the HAVRIX vaccine induces a 2X (50%) reduction in the MAVX- / - model. 2.7. vaccination with eHP particles, in the absence of any adjuvant, provided an increased protection against a challenge of 108HAV infectious units in both MAVS- / - and IFNR- / - mouse models compared with vaccination with nL0 particles administered with alumina as determined by a lower titre of negative sense RNA copies in the liver (Figure 10). Specifically, eHP vaccination show a 158X (99%) and a 3X reduction (67%) in HAV negative RNA copies, respectively in each mice model, compared with non- vaccinated and similarly challenged animals. In contrast, nL0 vaccinated mice showed a 10X (90%) reduction in the MAVS- / - mouse model, similar to the reduction observed using the HAVRIX vaccine (26X reduction equivalent to a (96%) and almost no reduction (1.17X reduction equivalent to a 21% reduction) in the IFNR- / - mouse model. 2.8. vaccination with eHP particles, in the absence of any adjuvant, provided an increased protection against a challenge of 108HAV infectious units in an IFNR- / - mouse model compared with vaccination with nHP particles administered with alumina as determined by the number of liver immune cell infiltrates (Figure 11). Specifically, vaccination with eHP particles induces a 6.7X reduction (85%) in liver immune cell infiltrates compared with non-vaccinated and similarly challenged animals. In contrast, nL0 vaccinated mice showed 4.6X reduction (78%) of liver infiltrates. 2.9. vaccination with eHP particles, in the absence of any adjuvant, provided a similar protection against a challenge of 108HAV infectious units in both the MAVS- / - and IFNR- / - mice models compared with vaccination with nL0 particles administered with alumina as determined by virus shedding in faeces (Figure 12). Specifically, vaccination with eHP particles induces a 2.6X reduction (62%) and a 1.9X reduction (46%) in virus shedding in faeces in both mice models, respectively, compared with non-vaccinated and similarly challenged animals. In contrast, nL0 vaccinated mice showed a 1.4X (27%) and a 2.3X (58%) reduction of viruses in faeces, in both models, respectively. 2.10. eHP particles, in the absence of any adjuvant, induce an enrichment of IgG2a compared with nL0 particles with alumina. This enrichment explains the higher level of protection of the eHP particles, in the absence of any adjuvant, in front of an HAV challenge (Figures 9-12).

[0002] CLAUSES 1. A composition, preferably a vaccine composition, capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, the vaccine comprising Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, wherein the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are obtained by a method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides; b. infecting said cell line with a hepatovirus or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids or hepatovirus antigenic polypeptides; and c. recovering, isolating, and / or purifying the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, or the cell supernatant comprising the same. 2. The composition according to clause 1, wherein the composition comprises Extracellular Vesicles (EVs) loaded with inactivated hepatovirus viral capsids or wherein the method comprises an inactivation step of the hepatovirus viral capsids loaded in the EVs. 3. The composition according to any one of clauses 1 or 2, wherein said cell line is selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial). Preferably, said cell line is the FRhK-4 cell line or Vero cells. 4. The composition according to clause 3, wherein the culturing step of the cell line to provide the culture supernatant is carried out by growing the cells, preferably Vero cells, in a cell medium in the absence of serum. 5. The composition according to any one of clauses 1 to 4, wherein the Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are exosomes. 6. The composition according to any one of clauses 1 to 5, wherein the hepatovirus is the human hepatitis A virus (HAV). 7. The composition according to any one of clauses 1 to 6, wherein the genetic element of interest is selected from the group consisting of any DNA, RNA or polynucleotide analogues thereof encoding a member selected from the group consisting of proteins or fragments of proteins of at least a hepatovirus antigenic polypeptide. 8. The composition according to clause 7, wherein the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 9. The composition according to any of clauses 1 to 6, wherein the EVs are naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting the cell line with the HM175-HP strain (HP). 10. The composition according to clause 9, wherein the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 11.The composition according to any of clauses 9 or 10, wherein the protein shell of the viral capsid is of SEQ ID NO 1, the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. 12.A vaccine composition, comprising naturally occurring EVs loaded with hepatovirus viral capsids capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A. 13.The vaccine composition of clause 12, wherein the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 14.The composition according to any of clauses 12 or 13, wherein the protein shell of the viral capsid is of SEQ ID NO 1 and the EVs are exosomes. 15.The composition according to any one of clauses 1 to 14, for use in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject.

Claims

CLAIMS 1. A composition, preferably a vaccine composition, capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, the composition comprising Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, wherein the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are obtained by a method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides; b. infecting said cell line with a hepatovirus or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids or hepatovirus antigenic polypeptides; and c. recovering, isolating, and / or purifying the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, or the cell supernatant comprising the same; wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs; and wherein the composition is for use in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject.

2. The composition for use according to claim 1, wherein the composition comprises hepatovirus viral capsids, and wherein more than 90%, 95%, 96%,97%, 98% or 99% of the total amount of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs.

3. The composition for use according to claim 2, wherein the hepatovirus viral capsids are inactivated hepatovirus viral capsids or the method comprises an inactivation step of the hepatovirus viral capsids.

4. The composition for use according to any one of claims 1 to 3, wherein said cell line is selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), wherein preferably, said cell line is the FRhK-4 cell line or Vero cells.

5. The composition for use according to claim 4, wherein the culturing step of the cell line to provide the culture supernatant is carried out by growing the cells, preferably Vero cells, in a cell medium in the absence of serum.

6. The composition for use according to any one of claims 1 to 5, wherein the Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are exosomes.

7. The composition for use according to any one of claims 1 to 5, wherein the hepatovirus is the human hepatitis A virus (HAV).

8. The composition for use according to any one of claims 1 to 7, wherein the genetic element of interest is selected from the group consisting of any DNA, RNA or polynucleotide analogues thereof encoding a member selected from the group consisting of proteins or fragments of proteins of at least a hepatovirus antigenic polypeptide.

9. The composition for use according to claim 8, wherein the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragment sequence thereof, or an immunogenic sequence having at least 80%,85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 10.The composition for use according to any of claims 2 to 7, wherein the EVs are naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting the cell line with the HM175-HP strain (HP).

11. The composition for use according to claim 10, wherein the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 12.The composition for use according to any of claims 10 or 11, wherein the protein shell of the viral capsid is of SEQ ID NO 1, the cell line is selected from FRhK- 4 or Vero cells, and the EVs are exosomes. 13.A vaccine composition, comprising naturally occurring EVs loaded with hepatovirus viral capsids capable of generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs. 14.The vaccine composition of claim 13, wherein the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 15.The composition according to any of claims 13 or 14, wherein the protein shell of the viral capsid is of SEQ ID NO 1 and the EVs are exosomes. 16.A vaccine composition, comprising naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting a cell line selected from the listconsisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably FRhK-4 cells or Vero cells, with the HM175-HP strain (HP), wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs.

17. The vaccine composition according to claim 16, wherein the hepatovirus viral capsids produced by the HM175-HP strain (HP) are inactivated hepatovirus viral capsids. 18.The composition according to any one of claims 13 to 17, for use in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject. 19.A method for producing a composition comprising EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, the method comprising: a. preparing a cell line susceptible to an infection with Hepatovirus and able to release in a culture supernatant EVs loaded with viral capsids of hepatovirus or hepatovirus antigenic polypeptides; b. infecting a cell line selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably FRhK-4 cells or Vero cells, with a hepatovirus or transiently or permanently transfecting with a viral construct comprising a genetic element of interest coding for at least a hepatovirus antigenic polypeptide into said cell line; and culturing the cell line to provide the culture supernatant comprising the EVs loaded with viral capsids or hepatovirus antigenic polypeptides; and c. recovering, isolating, and / or purifying the EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides, or the cell supernatant comprising the same;wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids or hepatovirus antigenic polypeptides present in the composition are hepatovirus viral capsids or hepatovirus antigenic polypeptides loaded in EVs. 20.The method according to claim 19, wherein the cell line is infected with a hepatovirus, and wherein more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of the hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs, and wherein preferably the method comprises an inactivation step of the hepatovirus viral capsids. 21.The method according to any one of claims 19 or 20, wherein said cell line is selected from the list consisting of FRhK-4 cells and Vero cells. 22.The method according to claim 21, wherein the culturing step of the cell line to provide the culture supernatant is carried out by growing the cells, preferably Vero cells, in a cell medium in the absence of serum. 23.The method according to any one of claims 19 to 22, wherein the Extracellular Vesicles (EVs) loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides are exosomes. 24.The method according to any one of claims 19 to 23, wherein the hepatovirus is the human hepatitis A virus (HAV). 25.The method according to any one of claims 19 to 24, wherein the genetic element of interest is selected from the group consisting of any DNA, RNA or polynucleotide analogues thereof encoding a member selected from the group consisting of proteins or fragments of proteins of at least a hepatovirus antigenic polypeptide. 26.The method according to claim 25, wherein the genetic element of interest encodes the immunogenic polypeptide of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647), or an immunogenic fragmentsequence thereof, or an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 27.The method according to any of claims 20 to 24, wherein the EVs are naturally occurring EVs loaded with hepatovirus viral capsids produced by infecting a cell line selected from the list consisting of FRhK-4 cells (Fetal Rhesus kidney epithelial), MRC-5 cells (Medical Research Council cell strain 5; human diploid lung fibroblasts), and Vero cells (African green monkey kidney epithelial), preferably FRhK-4 cells or Vero cells, with the HM175-HP strain (HP), wherein at least more than 90%, 95%, 96%, 97%, 98% or 99% of the total amount of hepatovirus viral capsids present in the composition are hepatovirus viral capsids loaded in EVs.

28. The method according to claim 27, wherein the protein shell of the viral capsids loaded in the EVs is of SEQ ID NO 1 (amino acid sequence corresponding with GenBank KX088647) or of an immunogenic sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% sequence identity with SEQ ID NO 1. 29.The method according to any of claims 27 or 28, wherein the protein shell of the viral capsid is of SEQ ID NO 1, the cell line is selected from FRhK-4 or Vero cells, and the EVs are exosomes. 30.A composition comprising comprising EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides obtained by the method of any one of claims 19 to 29. 31.A composition comprising comprising EVs loaded with hepatovirus viral capsids or hepatovirus antigenic polypeptides obtained by the method of claim 27. 32.The composition according to claim 30, for use in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject.The composition according to claim 31, for use in generating an immunogenic and / or protective immune response in a subject in need thereof against Hepatitis A, preferably in a human subject.

Images