Immunogenicity Of Two Porcine Epidemic Diarrhea Virus S1 Subunit Vaccines

Epidemiology shows significant variation in the prevalent strain of the Porcine epidemic diarrhea virus(Porcine epidemic diarrhea virus,PEDV),and commercialized vaccines based on the classic strain CV777 do not provide effective protection for pigs.Vaccines are an effective strategy to prevent PED.There is currently no effective vaccine to protect pigs from PEDV mutant strain infection,which is a serious threat to the pig industry worldwide.For the development of PEDV new vaccine,S1 gene of porcine epidemic diarrhea virus(PEDV)epidemic strain KM242131(Gen Bank: KM242131.1)was codonoptimized and expression design.Lentiviral expression system and recombinant adenovirus expression system were used to obtain recombinant cell lines HEK-293TS1 and Ad-S1 recombinant adenovirus that efficiently and stably express S1 protein.Animal experiments were performed to evaluate the immunogenicity of the new vaccine.In addition,a 3-day-old piglet of Bama minipig was challenged to prepare a pathological model.The main conclusions are as follows:(1)The protein S1 combined with oil-based adjuvant 206 and water-based adjuvant 1313,respectively,could effectively induce the production of specific saliva and feces SIg A through intramuscularimmunization.The serum virus neutralization test three weeks after immunization revealed that the antibody titer of S1+206 group was1:56 and that of S1+1313 group was 1:43,significantly different from that of the control group(P < 0.01).(2)The three PEDV strains identified had significant differences in S1 gene and the classical strain CV777,with low homology.Challenge of the GX-YL011 epidemic strain found that 3-day-old Piglets of Bama minipigs were susceptible to PEDV,which could be used as a pathological animal model.(3)Recombinant adenovirus Ad-S1 can quickly cause a strong mucosal immune response in mice through the nasal immunization route,and the level of SIg A antibody in feces and saliva 2 weeks after immunization was significantly higher than that of the control group(P<0.05),and It can be effective for 10 weeks(P<0.05);The nucleic acid adjuvant CPG ODN can promote mucosal immune response without obvious immune enhancement;Ad-S1/206+S1 combined immunization can induce high-level expression of Ig G;the recombinant adenovirus does not cause specific mucosal reactions in piglets,and the reasons need to be explored.In summary,the two new vaccines based on PEDV S1 sequence established in this study can induce specific mucosal immune responses in animal bodies.PEDV pathological model was prepared in 3-day-old Bama piglets to lay a foundation for further evaluation and pathological study of PEDV vaccine in the future.