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Pathogenicity and immunogenicity of a new strain of porcine epidemic diarrhea virus containing a novel deletion in the N gene.

ABSTRACT: Since late 2010, highly virulent PEDV G2-genotype strains have emerged globally extracting heavy losses on the pork industries of numerous countries. We investigated the characteristics of a field strain of PEDV (PEDV strain SH) isolated from a piglet with severe diarrhea on a farm in Shanghai China. Whole genome sequencing and analysis revealed that the SH strain belonged to subtype G2b and has a unique 12-aa deletion (aa 399-410) including the antigenic epitope NEP-1C9 (aa 398-406) of the N protein. PEDV SH strain is highly pathogenic to challenged newborn piglets, resulting in 100 % morbidity and mortality. Pathological examination revealed significant villus atrophy in the jejuna of infected piglets. Mice inoculated with inactivated PEDV SH produced antibodies against the N protein, but no antibodies against the deletions. These results illustrated that deletion of the NEP-1C9 epitope had no effect on the immunogenicity or pathogenicity of PEDV, providing evidence of the necessity to monitor the genetic diversity of the virus. Our study also contributes to development of candidate for vaccines and diagnostics that could differentiate pigs seropositive due to vaccination by conventional strains from wild virus infection.

SUBMITTER: Wang XW

PROVIDER: S-EPMC7173345 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Pathogenicity and immunogenicity of a new strain of porcine epidemic diarrhea virus containing a novel deletion in the N gene.

Wang Xian-Wei XW Wang Mi M Zhan Jing J Liu Qian-Yu QY Fang Lin-Lin LL Zhao Chen-Yao CY Jiang Ping P Li Yu-Feng YF Bai Juan J

Veterinary microbiology 20191115

Since late 2010, highly virulent PEDV G2-genotype strains have emerged globally extracting heavy losses on the pork industries of numerous countries. We investigated the characteristics of a field strain of PEDV (PEDV strain SH) isolated from a piglet with severe diarrhea on a farm in Shanghai China. Whole genome sequencing and analysis revealed that the SH strain belonged to subtype G2b and has a unique 12-aa deletion (aa 399-410) including the antigenic epitope NEP-1C9 (aa 398-406) of the N pr ...[more]

PMID: 31902508

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Project description:BackgroundPorcine epidemic diarrhea virus (PEDV) causes diarrhea in all ages of pigs with 50-100% mortality rates in neonatal piglets. In the United States, inactivated and subunit PEDV vaccines for pregnant sows are available, but fail to induce sufficient protection in neonatal piglets farrowed from PEDV naïve sows. A safe and efficacious live attenuated vaccine that can prime mucosal immune responses is urgently needed. In this study, we evaluated the safety and efficacy of two attenuated PEDV vaccine candidates, the emerging non-S INDEL PEDV strain PC22A at the 100th cell culture passage level - Clone no. 4 (P100C4) and at the 120th passage level (P120), in weaned pigs.ResultsFour groups of 40-day-old weaned pigs were inoculated orally with PEDV PC22A-P3 (virulent), -P100C4, -P120, and mock, respectively, and challenged with the P3 virus at 24 days post-inoculation (dpi). After inoculation, P3 caused diarrhea in all pigs with a high level of fecal viral RNA shedding. P100C4 and P120 did not cause diarrhea in pigs, although viral RNA was detected in feces of all pigs, except for one P100C4-inoculated pig. Compared with the P120 group, P3- and P100C4-inoculated pigs had higher serum PEDV-specific IgG and viral neutralizing (VN) antibody (Ab) titers at 14 dpi. After the challenge, no pigs in the P3 group but all pigs in the P100C4, P120, and mock groups had diarrhea. Compared with the P120 group, pigs in the P100C4 group had a more rapid decline in fecal PEDV RNA shedding titers, higher titers of serum PEDV-specific IgG, IgA, and VN Abs, and higher numbers of intestinal IgA Ab-secreting cells.ConclusionsPEDV PC22A P100C4 and P120 were fully attenuated in weaned pigs but failed to elicit protection against virulent P3 challenge. P100C4 induced higher PEDV-specific antibody responses than P120 post inoculation resulting in a greater anamnestic response post challenge. Therefore, P100C4 potentially could be tested as a priming vaccine or be further modified using reverse genetics. It also can be administered in multiple doses or be combined with inactivated or subunit vaccines and adjuvants as a PEDV vaccination regimen, whose efficacy can be tested in the future.

Project description:Porcine epidemic diarrhea (PED) caused by porcine epidemic diarrhea virus (PEDV), is an acute and highly infectious disease, resulting in substantial economic losses in the pig industry. Given that PEDV primarily infects the mucosal surfaces of the intestinal tract, it is crucial to improve the mucosal immunity to prevent viral invasion. Lactic acid bacteria (LAB) oral vaccines offer unique advantages and potential applications in combatting mucosal infectious diseases, making them an ideal approach for controlling PED outbreaks. However, traditional LAB oral vaccines use plasmids for exogenous protein expression and antibiotic genes as selection markers. Antibiotic genes can be diffused through transposition, transfer, or homologous recombination, resulting in the generation of drug-resistant strains. To overcome these issues, genome-editing technology has been developed to achieve gene expression in LAB genomes. In this study, we used the CRISPR-NCas9 system to integrate the PEDV S1 gene into the genome of alanine racemase-deficient Lactobacillus paracasei △Alr HLJ-27 (L. paracasei △Alr HLJ-27) at the thymidylate synthase (thyA) site, generating a strain, S1/△Alr HLJ-27. We conducted immunization assays in mice and piglets to evaluate the level of immune response and evaluated its protective effect against PEDV through challenge tests in piglets. Oral administration of the strain S1/△Alr HLJ-27 in mice and piglets elicited mucosal, humoral, and cellular immune responses. The strain also exhibited a certain level of resistance against PEDV infection in piglets. These results demonstrate the potential of S1/△Alr HLJ-27 as an oral vaccine candidate for PEDV control. KEY POINTS: • A strain S1/△Alr HLJ-27 was constructed as the candidate for an oral vaccine. • Immunogenicity response and challenge test was carried out to analyze the ability of the strain. • The strain S1/△Alr HLJ-27 could provide protection for piglets to a certain extent.

Dataset Information

Pathogenicity and immunogenicity of a new strain of porcine epidemic diarrhea virus containing a novel deletion in the N gene.

Publications

Pathogenicity and immunogenicity of a new strain of porcine epidemic diarrhea virus containing a novel deletion in the N gene.

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