Porcine epidemic diarrhea virus variant strain and application thereof

Abstract

The application provides a porcine epidemic diarrhea virus mutant strain and application thereof. The application obtains a porcine epidemic diarrhea virus mutant strain GX2506 from porcine intestinal tissue, and the strain is purified through passage, and the microorganism preservation number of the strain is CGMCC No. 47089. The isolated strain can stably proliferate on a passage cell, and typical cytopathic effect is generated. The porcine epidemic diarrhea virus mutant isolated strain has excellent immunogenicity; a vaccine prepared by using the isolated strain can induce piglets to generate high-level neutralizing antibodies; meanwhile, an ELISA kit prepared by using the isolated strain can better detect porcine epidemic diarrhea virus antibodies in serum.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology, specifically relating to an isolated and purified variant strain of porcine epidemic diarrhea virus and its application. Background Technology

[0002] Porcine epidemic diarrhea (PED) is caused by the porcine epidemic diarrhea virus (PEDV). Porcine epidemic diarrhea virus Porcine epidemic diarrhea (PEDV) is a highly contagious gastrointestinal disease caused by pathogens that cause acute watery diarrhea, vomiting, dehydration, and weight loss in infected pigs. Pigs of all ages can be infected, but piglets under 7 days old show the most pronounced symptoms, with morbidity and mortality rates reaching up to 100%. PEDV was first reported in the UK in the 1970s, and CV777 was subsequently successfully isolated. In 1982, the pathogen was officially named porcine epidemic diarrhea virus. In my country, the first PEDV strain was isolated in 1984, initially occurring sporadically with minimal impact on the pig farming industry. However, in 2010, several large-scale pig farms in southern my country experienced a sudden outbreak of PEDV, which subsequently swept across the country, characterized by its young age of infected pigs and high mortality rate, severely impacting the pig farming industry.

[0003] PEDV belongs to the order Nidovirales, family Coronaviridae, and genus Alphacoronavirus. Its genome is an enveloped, single-stranded, positive-sense RNA that primarily encodes four structural proteins: nucleocapsid protein (N), spike protein (S), membrane glycoprotein (E), and matrix protein (M). Among these, the N protein has the highest conservation and is commonly used for the differential diagnosis of this disease. The S protein is a key protein for PEDV invasion of host cells, playing a crucial role in viral virulence, species and tissue tropism, and inducing the production of neutralizing antibodies in the host. The S gene exhibits high genetic variability and is frequently used to analyze the genetic characteristics of viral isolates. Based on different S gene sequences, PEDV strains can be classified into G1, G2, and Indel types (recombinant strains of G1 and G2). G1 and G2 types can be further subdivided into G1a, G1b, G2a, G2b, and G2c.

[0004] The S gene of the G1 strain is mainly 4152 bp in length, encoding 1383 amino acids, while the S gene of the G2 strain is typically 4158 bp or 4161 bp in length. The G1 and G2 S genes differ significantly, with notable differences in important epitopes (248–280 aa, 442–499 aa, 697–742 aa). Furthermore, multiple sites show consecutive deletions and insertions of several amino acids. Compared to the classic strain CV777, most G2 strains also exhibit insertions and deletions at key amino acid sites. There are hundreds of different amino acid sites in the G1 and G2 S protein, with most of these differences concentrated in the S1 region. Mutations in the S gene amino acids can alter viral phenotype, virulence, tropism, and neutralizing activity.

[0005] With the large-scale and intensive development of the pig farming industry and the increasing frequency of global trade, outbreaks of porcine epidemic diarrhea virus (PEDV) pose a serious threat to the industry, causing not only mass mortality of piglets but also significant economic losses to agricultural production. Currently, there is no specific drug treatment for this disease, making the development of effective drugs or vaccines crucial. Vaccination is the most powerful preventative and control measure. However, vaccines developed based on classic strains are no longer sufficient to effectively curb the further spread of the epidemic, especially with the emergence of the G2 variant PEDV strain becoming a major cause of widespread piglet mortality. Currently, the PEDV variant strain is showing an epidemic trend in some regions of my country, causing considerable harm and economic losses to the livestock industry. However, traditional isolation and large-scale culture of PEDV present challenges, and viral titers are generally low; currently, there are no commercially available PEDV vaccines with particularly ideal efficacy. Research on PEDV vaccines and diagnostic methods is also relatively limited. Timely development of highly effective vaccines and diagnostic kits is of great significance for the prevention and control of this disease. Summary of the Invention

[0006] The purpose of this invention is to provide a variant strain of porcine epidemic diarrhea virus and its S gene sequence, as well as the application of inactivated vaccines prepared based on the isolates in the prevention and control of porcine epidemic diarrhea virus.

[0007] To achieve the objectives of this invention, the technical solution is as follows: In a first aspect, the present invention provides a variant strain of porcine epidemic diarrhea virus (PEDV). Porcine epidemic diarrhea virus ,PEDV) strain and its S gene sequence.

[0008] This invention involves inoculating Vero cells with a homogenized extract of pig intestinal tissue from a pig farm in Guangxi. After cell passage, purification, and identification, a variant strain of porcine epidemic diarrhea virus was obtained and classified as: porcine epidemic diarrhea virus. ， Named GX2506, it exhibits stable proliferation on cells, and its CT value for porcine epidemic diarrhea virus (PEDV) reaches 15 and TCID is high, as determined by quantitative real-time assay. 50 Up to 1.0 × 10 7.0 TCID 50 The sample, at / mL, was deposited on December 9, 2025, at the China General Microbiological Culture Collection Center (Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing), with accession number CGMCC No. 47089. This invention provides the S gene sequence of a variant isolate of porcine epidemic diarrhea virus, as shown in SEQ ID No. 1.

[0009] Secondly, the present invention provides a biological product containing the aforementioned variant strain of porcine epidemic diarrhea virus, the biological product being used for the prevention or diagnosis of porcine epidemic diarrhea virus disease.

[0010] The biological product may be a vaccine or a diagnostic reagent.

[0011] The vaccine mentioned is either a live vaccine or an inactivated vaccine.

[0012] This invention provides an inactivated vaccine comprising an isolated variant strain of porcine epidemic diarrhea virus (PEDV). The inactivated vaccine is prepared by passage of Vero cells with porcine epidemic diarrhea virus strain GX2506, harvesting the viral fluid, determining the viral titer, and then mixing it with an adjuvant at a 1:1 weight ratio. Available adjuvants include a self-made gelatinous aqueous adjuvant from China Animal Husbandry Industry Co., Ltd., 201VG from Sepik Pharmaceutical Co., Ltd., and conventional aluminum adjuvants.

[0013] The antigen content of the inactivated vaccine is not less than 1.0 × 10⁻⁶ per dose. 7.0 TCID 50 / mL, the immunization route is intramuscular injection or nasal inoculation, preferably intramuscular injection.

[0014] The reagent provided by this invention can be an ELISA kit containing the isolated variant strain of porcine epidemic diarrhea virus, which can effectively detect antibodies in serum.

[0015] Thirdly, the present invention also provides the use of the porcine epidemic diarrhea virus variant strain in the preparation of a vaccine for the prevention of viral diseases caused by porcine epidemic diarrhea virus; and the use of the porcine epidemic diarrhea virus strain in the preparation of a reagent for the diagnosis of viral diseases caused by porcine epidemic diarrhea virus.

[0016] The beneficial effects of this invention are as follows: The porcine epidemic diarrhea virus variant strain obtained by this invention proliferates rapidly and with a high titer (up to 1.0 × 10⁻⁶) in susceptible cells (Vero cell line). 7.0 TCID 50 / mL; The porcine epidemic diarrhea virus variant strain of this invention has strong pathogenicity, using 1.0×10 7.0 TCID 50 Newborn piglets were challenged with a nasal cavity virus solution of / mL and observed for 10 consecutive days. On the first day after the challenge, the piglets developed fever and diarrhea, which worsened, leading to severe dehydration and persistent tremors. The symptoms only subsided after 7 days. The virus was not fatal, but the piglets still showed slow development, rough coat, and depression.

[0017] The inactivated vaccine prepared using the strain of this invention has good immunogenicity and can induce piglets to produce high levels of neutralizing antibodies, providing important biological materials for the effective prevention and control of porcine epidemic diarrhea virus disease.

[0018] ELISA is characterized by high sensitivity, good specificity, and the ability to be performed in batches, making it convenient for clinical application. This invention provides an ELISA kit containing an isolated variant strain of porcine epidemic diarrhea virus (PEDV), which can effectively detect PEDV antibodies in serum, providing an important foundation for the effective detection of this disease.

[0019] Based on this, other biological products prepared using the porcine epidemic diarrhea virus variant strain described in this invention for the prevention and diagnosis of porcine epidemic diarrhea virus disease also fall within the scope of protection of this invention.

[0020] In 2025, this study isolated and purified a variant strain of porcine epidemic diarrhea virus (PEDV), named GX2506, from intestinal tissue of pigs at a pig farm in Guangxi. This isolate exhibited good proliferation in passaged cells, moderate pathogenicity in piglets, and excellent immunogenicity, inducing high levels of neutralizing antibodies in piglets, thus laying a solid foundation for the effective control of PEDV. Furthermore, an ELISA kit prepared using this isolate effectively detected PEDV antibodies in serum, providing a technical basis for the effective diagnosis of PEDV. Attached Figure Description

[0021] Figure 1 The images show cytopathic effects (CPE) of a variant strain of porcine epidemic diarrhea virus (PEDV) cultured on Vero adherent cells. In the images, A represents the cytopathic effect (CPE) of the GX2506 variant strain of PEDV on Vero cells, and B represents normal Vero cells as a control. Preservation of biological materials

[0022] Accession number: CGMCC No. 47089 Name: GX2506 Classification and nomenclature: Porcine epidemic diarrhea virus Preservation Institution: China General Microbiological Culture Collection Center (CGMCC) Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing Preservation period: December 9, 2025 Survival status: Yes. Detailed Implementation

[0023] Unless otherwise specified, the methods described in the following embodiments are conventional methods.

[0024] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the reagents used are all commercially available products.

[0025] Example 1: Isolation of a variant strain of porcine epidemic diarrhea virus 1. Collection and processing of intestinal tissue Collect pig intestinal tissue, cut it into small pieces, add 10 times the volume of DMEM medium containing 500 units of double antibiotics and grind it. Centrifuge at 12,000 rpm for 5 min at 4℃, collect the supernatant of the grinding liquid, and freeze it at -80℃ for later use.

[0026] 2. Detection of pathogens in intestinal tissue Take 200 μL of the supernatant from the above-mentioned homogenate and extract nucleic acid using the DNA / RNA extraction kit from Beijing TransGen Biotech Co., Ltd., following the manufacturer's instructions. Then, reverse transcribe the RNA into cDNA using the TransGen reverse transcription kit. Using the extracted DNA and reverse-transcribed cDNA as templates, PCR detection was performed using primers for classical classical swine fever virus (CSFV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine pseudorabies virus (PRV), porcine circovirus type 2 / 3 (PCV2 / PCV3), porcine parvovirus (PPV), transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), porcine rotavirus (PoRV), and porcine deltacoronavirus (PDCoV). The test results showed that the homogenate sample was positive for porcine epidemic diarrhea virus, while other pathogens were negative.

[0027] 3. Isolation of variant strains of porcine epidemic diarrhea virus In 2025, intestinal tissue was collected from an infected pig farm in Guangxi Province. The intestinal tissue material tested positive by RT-PCR. Pigs in the infected farm exhibited watery diarrhea accompanied by vomiting and other clinical symptoms. The collected intestinal tissue from the infected pigs was inoculated into Vero cells. After incubation for 1 hour, the incubation medium was discarded, and the culture was maintained in serum-free DMEM containing 5 μg / mL trypsin. 72 hours after inoculation, the cells showed shrinkage, syncytial aggregation, and a small amount of shedding, while normal cells showed no cytopathic effects. Cell cultures were harvested 5 days after inoculation and passaged three times consecutively in Vero cells. The fourth generation was inoculated into Vero cells. After 16 hours, the cells showed significant aggregation, shrinkage, and a small amount of shedding. Virus was harvested 20 hours after inoculation and passaged three times consecutively in Vero cells, consistently showing cytopathic effects (CPE). Nucleic acid extraction and reverse transcription of the sixth generation product were performed, and PCR detection identified it as porcine epidemic diarrhea virus (PEDV), thus confirming the successful isolation of PEDV.

[0028] The S gene of porcine epidemic diarrhea virus (PEDV) was amplified. The amplified product was subjected to 1% agarose gel electrophoresis. After a positive band of the target size appeared, the band was excised, purified, and sent to Beijing Qingke Biotechnology Co., Ltd. for sequencing. The PEDV S gene sequence was obtained, as shown in SEQ ID No. 1. The obtained PEDV S gene nucleic acid sequence was compared online with NCBI Blast, and the highest homology was found to be 99.86% with existing PEDV strain sequences (online comparison URL: https: / / blast.ncbi.nlm.nih.gov / Blast.cgi). Therefore, this strain was identified as a novel PEDV strain.

[0029] The isolated virus was passaged and propagated in Vero adherent cells. A variant strain of porcine epidemic diarrhea virus (PEDV) cultured in the 6th generation was inoculated into Vero adherent cells at a ratio of 0.2%. Fifteen hours after inoculation, aggregated and fused cytopathic effects appeared in the cells, while normal cells showed no obvious cytopathic effects. Cell cultures were harvested after 18 hours. The isolated PEDV strain was then passaged to the 7th generation. After 15 hours of culture, obvious cytopathic effects were observed. After positive identification, a new PEDV strain was obtained and named GX2506, classified as Porcine Epidemic Diarrhea Virus (PEDV). Porcine epidemic diarrhea virus The porcine epidemic diarrhea virus strain GX2506 has been deposited at the China General Microbiological Culture Collection Center (address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing) on ​​December 9, 2025, with accession number CGMCC No. 47089.

[0030] Porcine epidemic diarrhea virus isolates were inoculated into Vero adherent cells for culture. Typical cytopathic effects appeared after 15-18 hours, such as... Figure 1 As shown. When the cytopathic effect reached approximately 90%, the culture was harvested, subjected to one freeze-thaw cycle, and the viral titer was determined to be 1.0 × 10⁻⁶ according to the Reed & Muench method. 7.0 TCID 50 / mL.

[0031] Example 2: Pathogenicity test of porcine epidemic diarrhea virus variant strain GX2506 Six newborn piglets that were negative for porcine epidemic diarrhea virus (PEDV) pathogen and antibodies were randomly divided into two groups of three piglets each. The experimental group underwent oral challenge, with each piglet inoculated with 2 mL of 10... 7.0 TCID 50 F7 passaged virus solution; each pig in the control group was orally inoculated with an equal volume of sterile PBS solution. The pigs' condition was observed daily, and rectal temperature was measured and recorded.

[0032] After 10 days of continuous observation, the control group pigs maintained normal body temperature, normal appetite, and no diarrhea; all pigs survived. The observation group pigs developed fever and diarrhea on day 1, which worsened, leading to severe dehydration and persistent tremors, only improving after 7 days. However, the piglets still exhibited slow development, rough coats, and lethargy. These data indicate that the porcine epidemic diarrhea virus isolate GX2506 is pathogenic to newborn piglets.

[0033] Blood and anal swabs were collected from each pig in the challenge group and control group before challenge (day 0) and at 1, 3, 5, 7, and 10 days after challenge. Serum was separated, and viremia and viral shedding were detected by RT-PCR. The results of viremia detection are shown in Table 1. The results of viral shedding detection are shown in Table 2. The data showed that some challenged pigs began to show viremia and viral shedding on day 1, all showed viremia and viral shedding by day 3, and no viremia or viral shedding was observed after day 10.

[0034] Table 1. Results of viremia detection before and after viral challenge.

[0035] Table 2. Pathogen detection results of anal swabs before and after viral challenge.

[0036] The challenge test data showed that the isolate of this invention caused newborn piglets to have clinical symptoms such as diarrhea after infection, but it was not lethal and was a moderately virulent strain.

[0037] Example 3: Application of isolate GX2506 in the preparation of inactivated porcine epidemic diarrhea virus vaccine 1. Preparation of inactivated vaccine from porcine epidemic diarrhea virus isolates The GX2506 isolate was inoculated into Vero cells at 1% of the culture volume and passaged continuously. The virus solution was harvested, frozen and thawed once, and the supernatant was collected by centrifugation to determine the virus titer. A virus titer greater than 10... 7.0 TCID 50 / mL, after passing sterility and exogenous virus testing, formaldehyde with a final concentration of 0.2% is added for inactivation.

[0038] Vaccine preparation method: Zhongmu's self-made gel-like aqueous adjuvant formula: 90% aqueous solution for injection, 3% lactic acid-hydroxyacetic acid (PLGA), 2% polyvinylpyrrolidone, 2% alkyl glycoside (decyl glucoside) (APG0816), 1% polyethylene glycol 6000, 1% polyoxyethylene sorbitan monooleate, and 1% cetyl alcohol. Wherein, % represents the mass percentage.

[0039] Weigh 9 g of the self-made gelatinous aqueous adjuvant from Zhongmu, mix it with an equal volume of inactivated antigen, and shake thoroughly to mix.

[0040] 2. Vaccine safety trials Twelve newborn piglets that were negative for porcine epidemic diarrhea virus (PEDV) pathogen and antibodies were randomly divided into four groups of three piglets each. The experimental group received two doses (4 mL) of inactivated vaccine intramuscularly, followed by a second vaccination 14 days later. The control group received an equal volume of sterile PBS solution intramuscularly, followed by a second PBS vaccination 14 days later. The piglets were observed for 21 consecutive days. Results showed no significant differences in mental state, body temperature, or daily weight gain between the experimental and control groups, and no adverse reactions were observed.

[0041] 3. Vaccine efficacy trials Twelve newborn piglets that were negative for porcine epidemic diarrhea virus (PEDV) pathogen and antibodies were randomly divided into four groups of three piglets each. The experimental group received one dose (2 mL) of inactivated vaccine intramuscularly, while the control group received an equal volume of sterile PBS solution intramuscularly. The piglets were observed for 35 consecutive days. Blood samples were collected on days 0, 7, 14, 21, 28, and 35. Serum was separated, inactivated at 56℃ for 30 min, and porcine epidemic diarrhea virus neutralizing antibodies were measured. The results of the neutralizing antibody test (as shown in Table 3) indicate that the inactivated vaccine prepared from the strain of this invention, after passage, produced high levels of neutralizing antibodies 28 days after immunization, demonstrating good immunogenicity.

[0042] Table 3. Results of neutralizing antibody detection after inactivated vaccine immunization.

[0043] Example 4: Application of isolate GX2506 in the preparation of an indirect ELISA detection kit 1. Propagate the GX2506 virus isolate for later use.

[0044] The isolate was amplified using Vero adherent cells. Once obvious cytopathic effects were observed in the cells, the virus was harvested and stored at -80°C, undergoing one freeze-thaw cycle. Cell debris was then removed by centrifugation at 6000 rpm for 5 min. The virus was purified using a sucrose density gradient centrifugation method. The purified virus was diluted with PBS, and protein concentration was measured.

[0045] 2. Specific steps of indirect ELISA.

[0046] (1) Coating with whole virus antigen: Purified GX2506 whole virus was used as the coating antigen. The optimal coating concentration of virus and the optimal serum dilution were determined by serial dilution of antigen and serum using the matrix method. The optimal coating concentration of virus was 2.0 μg / mL, and the optimal coating concentration of virus was 1:100. The purified virus was diluted with coating buffer and coated with 100 μL per well of the ELISA plate, and incubated overnight at 4°C.

[0047] (2) Discard the coating solution, wash 3 times with PBST, add 200 μL of 5% skim milk powder to each well, and block at 37°C for 2 hours. Discard the skim milk, and then wash 3-5 times with PBST for 3-5 minutes each time.

[0048] (3) Dilute the serum to be tested with PBS, then add 100 μL to each well and incubate at 37°C for 1 hour. Set up negative serum and positive serum controls at the same time. Discard the liquid and wash with PBST 3-5 times, 3-5 minutes each time.

[0049] (4) Determine the optimal conditions for the secondary antibody: The optimal dilution of the secondary antibody is 1:10000, and the optimal incubation time is 1 hour. Add 100 μL of diluted horseradish peroxidase-labeled anti-pig IgG secondary antibody to each well and incubate at 37°C for 1 hour. Discard the secondary antibody and wash with PBST 3-5 times, 3-5 minutes each time.

[0050] (5) Add 100 μL of TMB colorimetric solution to each well and develop the color for 10 minutes in the dark.

[0051] (6) Add 50 μL of stop solution (2 M H2SO4) to each well, OD 450 nm reading. Critical value for positive and negative: OD 450 A value ≥0.5 is considered positive; OD 450 A value <0.5 is considered negative.

[0052] 3. Sensitivity test of indirect ELISA detection kit Using the three batches of indirect ELISA detection kits (ZM202501~ZM202503) from Example 4, 50 swine serum samples (all wild-type infected serum, provided by China Animal Husbandry Industry Co., Ltd., and inactivated at 56℃ for 30 min) collected from a pig farm were tested according to the usage method described in Example 4. The experimental results are shown in Table 4. The kit of batch ZM202501 detected 49 samples, and the sensitivity of this kit for the 50 serum samples was 96.67%; the kit of batch ZM202502 detected 50 samples, and the sensitivity of this kit for the 50 serum samples was 100.00%; the kit of batch ZM202503 detected 50 samples, and the sensitivity of this kit for the 50 serum samples was 100.00%.

[0053] Table 4. Sensitivity test results of the indirect ELISA kit. reagent kit batch number Detection rate Sensitivity ZM202501 49 / 50 98.00% ZM202502 50 / 50 100.00% ZM202503 50 / 30 100.00% 4. Specificity test of indirect ELISA detection kit Using the three batches of indirect ELISA test kits (ZM202501~ZM202503) from Example 4, 40 healthy pig serum samples, 5 classical swine fever virus (CSFV) positive serum samples, 5 porcine reproductive and respiratory syndrome virus (PRRSV) positive serum samples, 5 porcine foot-and-mouth disease virus type O (FMDV-O) positive serum samples, and 5 porcine foot-and-mouth disease virus type A (FMDV-A) positive serum samples were tested according to the usage method described in Example 4.

[0054] The specificity test results of the kits are shown in Table 5 below. The test results for 40 healthy swine serum samples showed that the specificity of all batches of kits was 100.0%. The test results for 5 positive sera for classical swine fever virus (CSFV), 5 positive sera for porcine reproductive and respiratory syndrome virus (PRRSV), 5 positive sera for porcine foot-and-mouth disease virus type O (FMDV-O), and 5 positive sera for porcine foot-and-mouth disease virus type A (FMDV-A) were all negative. Therefore, the specificity of all three batches of kits for detecting these 20 positive sera for the relevant pathogens was 100%.

[0055] Table 5. Specificity detection results of the indirect ELISA assay kit.

[0056] 5. Comparison test between the indirect ELISA detection kit and the imported kit Seventy swine serum samples were tested using three batches of indirect ELISA kits (ZM202501~ZM202503) from Example 4 and a swine epidemic diarrhea virus antibody detection kit from a US company.

[0057] The results of the concordance rate test (Table 6) show that the indirect ELISA detection kit (batch number ZM202501) had a positive detection rate of 90.00% for 70 samples of swine serum, while the imported kit had a positive detection rate of 91.43%. The results were consistent for 67 samples. Therefore, the concordance rate between the present invention's kit and the imported kit is 95.71%, indicating high accuracy, and it can be used for the detection of porcine epidemic diarrhea virus antibodies.

[0058] The indirect ELISA detection kit (batch number ZM202502) showed a positive detection rate of 91.43% for 70 swine serum samples, the same as the imported kit. Results were consistent for 68 samples. Therefore, the concordance rate between this invention's kit and the imported kit is 97.14%, indicating high accuracy. This kit can be used for detecting porcine epidemic diarrhea virus antibodies.

[0059] The indirect ELISA detection kit (batch number ZM202503) showed a positive detection rate of 92.86% for 70 swine serum samples, while the imported kit showed a positive detection rate of 91.43%. Results were consistent for 69 samples. Therefore, the concordance rate between the present invention and the imported kit is 98.57%, indicating high accuracy, and the kit can be used for the detection of porcine epidemic diarrhea virus antibodies.

[0060] Table 6. Comparison test results between the indirect ELISA test kit and the imported kit.

[0061] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A variant strain of porcine epidemic diarrhea virus, characterized by: The variant strain of porcine epidemic diarrhea virus is named GX2506, classified as porcine epidemic diarrhea virus, and its accession number at the China General Microbiological Culture Collection Center is CGMCC No. 47089.

2. The porcine epidemic diarrhea virus variant strain according to claim 1, characterized in that: The S gene sequence of the porcine epidemic diarrhea virus variant strain is shown in Sequence 1 of the sequence listing.

3. A biological product containing a variant strain of porcine epidemic diarrhea virus as described in claims 1 and 2, said biological product being used for the prevention or diagnosis of viral diseases caused by porcine epidemic diarrhea virus.

4. The biological product according to claim 3, characterized in that: The biological products mentioned are vaccines or diagnostic reagents.

5. The biological product according to claim 4, characterized in that: The vaccine is either a live vaccine or an inactivated vaccine, and the vaccine also includes a pharmaceutically acceptable adjuvant.

6. The biological product according to claim 4, characterized in that: The diagnostic reagent is an ELISA kit, which includes an enzyme-labeled plate coated with the whole virus of porcine epidemic diarrhea virus (CGMCC No. 47089) and an enzyme-labeled secondary antibody.

7. The use of the porcine epidemic diarrhea virus variant strain according to claims 1 and 2 in the preparation of a vaccine for the prevention of viral diseases caused by porcine epidemic diarrhea virus.

8. The use of the porcine epidemic diarrhea virus variant strains of claims 1 and 2 in the preparation of reagents for diagnosing viral diseases caused by porcine epidemic diarrhea virus.

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