Vectors for molecule delivery to CD11b expressing cells

Abstract

The invention relates to a novel use of a Bordetella adenylcyclase toxin in the manufacturing of vectors for targeting in vivo a molecule of interest, specifically to CD11b expressing cells. The invention also relates to an immunogenic composition that primes immune responses, to pharmaceutical compositions, and to a new vector for molecule delivery to CD11b expressing cells.

Description

BACKGROUND OF THE INVENTION [0001] The invention relates to a novel use of a Bordetella adenylcyclase toxin in the manufacturing of vectors for targeting in viva a molecule of interest, specifically to CD11b expressing cells. The invention also relates to an immunogenic composition that primes immune responses, to pharmaceutical compositions and a new vector for molecule delivery to CD11b expressing cells. [0002]Bordetella pertussis, the causative agent of whooping cough, secretes several toxins including the well-known pertussis toxin (PT) and the adenylate cyclase toxin (CyaA) or also adenylcyclase. CyaA is a critical virulence factor of B. pertussis in the murine respiratory model that is required for the early steps of lung colonization. Indeed, genetic deletion of this toxin dramatically decreases the pathological effects of B. pertussis infection, reducing the number of bacteria recovered from the lung and almost abolishing the inflammatory cell recruitnent and the lung lesion...

AI Technical Summary

Benefits of technology

[0033] In particular, in one embodiment, the targeting of said molecule or peptide is effective in vivo.

[0054] As used herein, the term “permissive site” relates to a site where the heterologous molecule and especially a peptide can be inserted without substantially affecting the desired functional properties of the adenylcyclase toxin, i.e. without affecting the domains necessary for the specific binding to CD11b / CD18 receptor and advantageously without affecting the process of translocation of the catalytic domain. In a preferred embodiment, the capacity of the CyaA toxin to promote the synthesis of cAMP in the targeted cells is further maintained.

[0055] Methods to select for permissive sites are presented for example in WO93 / 21324 and in Ladant et al., 1992. In particular, a methodology using a double selection (resistance to an antibiotic and calorimetric test on dishes by α-complementation) enables to identify readily oligonucleotides insertions (which preserve the reading frame) in the portion of the gene coding for the N-terminal catalytic domain of the toxin. The functional consequences of these mutations on the catalytic activity of the toxin may be readily analysed, both genetically (functional complementation of an E. coli cya31 strain) and biochemically (characterization of the stability of the modified adenylcyclases, of their enzymatic activity, of their interaction with caM, etc.). This methodology has enabled a large number of mutations to be screened in order to identify the sites which are potentially advantageous for the insertion of antigenic determinants.

[0070] Applicant has also shown that CTL specific for the vectorized antigen can be primed in vivo after a single intravenous injection of the recombinant toxin, especially with no need to provide an heterologous adjuvant. These results shown in the experimental part and in particular the specific targeting of the epitope to myeloid dendritic cells enable new immunization strategies that bypass the requirement for adjuvant and CD4+ T cell help.

[0086] The applicants have shown that in vivo intravenous administration of the immunogenic composition in an animal or human host as defined in the present invention without adjuvant(s) is sufficient to promote efficiently an immune response in said animal or human host.

Problems solved by technology

However, the molecular mechanisms by which the toxin transports its N-terminus catalytic domain across the membrane remain largely unknown to date.

Moreover, despite numerous in vitro promising studies, no vector was shown to be exclusively targeted to pAPC particularly to dendritic cells and more particularly to myeloid dendritc cells.

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