Molecular characterization of circulating porcine circovirus 2 pcv2 and development of inactivated vaccine

Abstract

The present study was aimed at molecular characterization of the circulating porcine circovirus 2 (PCV2) under field condition in southern India and development of a inactivated vaccine. A total of 434 field samples comprising of serum (n=273), post mortem tissues (n=109) and swabs from natural orifices (n=52) collected from swine populations of southern India during the period from 2019 to 2021 were used in this study. Of the 434 field samples screened, 53(12.2%) samples were found positive for PCV2 infections by ORF2 gene based diagnostic polymerase chain reaction (PCR) assay. Statistical analysis of PCV2 positivity within breed, age, sex and vaccination status revealed no significant difference (Pgt0.05) but there was a significant difference (Plt0.05) in the positivity of PCV2 among healthy and suspected swine populations. ELISA based PCV2 specific antibody to capsid protein screening in 176 serum samples collected from non-vaccinated animals (based on history) revealed seropositivity of 44.8% (n=79).Animals used in immunogenicity study for inactivated PCV2b and PCV2d vaccines were sub grouped and kept as non-booster and booster group within each vaccine group. In booster group, second dose of their respective inactivated PCV2 vaccine were given at 28th day post primary vaccination and evaluated for the immune response for a period of 120 dpv. Both the vaccinated groups showed significantly high serum antibody and neutralizing antibody (NA) response for upto 120 dpv in both booster and non-booster vaccinated groups, but the levels of serum antibody were started reducing in non-booster groups compared to booster group by 120 dpv in both the vaccine groups. Growth performances of pigs (ADWG) during the study period not differed significantly in all the groups. In conclusion, the formulated inactivated PCV2d and PCV2b genotypic specific vaccines are safe and elicited good neutralizing antibody titre upto 120 dpv and provided significant protection to their respective homologous genotypes. newline