Evaluation Of The Bivalent PCV2-VLP And Inactivated SVV Vaccine

In order to evaluate of the immunogenicity of bivalent Porcine circovirus type 2 Virus-like particles(PCV2-VLP)and inactivated Seneca Valley Virus(SVV)vaccines,equal amounts of PCV2-VLP vaccine and inactivated SVV vaccine were mixed.The integrity of PCV2-VLP particles were verified by transmission electron microscopy firstly.The results showed that the PCV2-VLP particles are complete and uniform in size,with a diameter of about 17 nm-20 nm,indicating that PCV2-VLP has good integrity and can be used for further vaccine research.Mice were immunized twice with bivalent PCV2-VLP and SVV inactivated vaccine,PCV2-VLP vaccine and SVV inactivated vaccine with 603 and carbomer as adjuvants respectively,and the control group was established meanwhile.After the initial immunization,antibodies and cytokines were examined by enzyme-linked immunosorbent assay(ELISA),and neutralizing antibodies were examined by neutralization test.The results showed that compared with carbomer adjuvant,bivalent PCV2-VLP and SVV inactivated vaccine,PCV2-VLP vaccine and SVV inactivated vaccine combined with 603 adjuvants could produce higher specific antibody and neutralizing antibody.With the same adjuvant,both mixed vaccine and PCV2 vaccine could induce a comparable level of PCV2 antibody,namely specific antibody and neutralizing antibody.SVV neutralizing antibody produced by the bivalent vaccine group were significantly higher the those of the single vaccine group.The cytokine levels were the same in each group.These findings suggest that 603 adjuvants were better than carbomer adjuvant;PCV2-VLP and SVV bivalent vaccine could produce high level neutralizing antibody against PCV2 and SVV,and had good immunogenicity.In general,the bivalent vaccine developed in this study has potential application value for the prevention of PCV2 and SVV.The combination of ISA201 adjuvant and bivalent PCV2-VLP vaccine with inactivated SVV vaccine which mixed at equal volume,or two vaccines separately were evaluated in pigs.The results showed that the immune protection effect of the mixed bivalent vaccine against PCV2 was similar with that of the PCV2 vaccine used alone.The immune protection against PCV2 challenge was 80% in both vaccine groups.After challenged with SVV.the pigs in the vaccinated groups had no clinical signs.In addition,the serum antibody levels of PCV2 and SVV were examined in piglet blood samples collected at different time points after immunization with bivalent vaccine,PCV2 vaccine and SVV vaccine,respectively.The results showed that bivalent vaccine,PCV2-VLP vaccine and SVV vaccine could induce a comparable level of PCV2 antibody or SVV antibody.It suggests that bivalent vaccine,PCV2-VLP vaccine and SVV vaccine could provide protective efficacy against PCV2 and SVV infection in swine.In general,the bivalent vaccine developed in this study has potential application value for the prevention against PCV2 and SVV infection.