Investigation on the immunogenicity in pigs of recombinant PCV2-ORF2 antigen based on baculovirus expression system

Abstract

In this study, the immunogenicity of recombinant ORF2 antigen of PCV2 was investigated
and their ability to protect piglets against a PCV2 challenge was evaluated. The studied
results showed that at doses of 106 and 107 pfu/ml, PCV2 specific antibodies were significantly
increased in serum of the experimental pigs injected with ORF2 antigen in comparison with the
control pig group (p<0,05 for dose of 106 pfu/ml and p<0,01 for dose of 107 pfu/ml). Additionally,
at high dose (107 pfu/ml), PCV2 specific antibodies appeared at 21 days after first injection
(p<0,05) and reached at peak at 42 days (p<0,01) when compared to PBS injection as the
control. In order to assess the ability for protecting the piglets against PCV2 challenge, at
day 42 after immunization with recombinant ORF2 antigen, the animals were challenged with
virulent PCV2 strain and the efficacy in reducing the PCV2 load in lymph node and serum were
determined by Semi-quantitative RT-PCR at day 14 after challenge. The results showed that,  the viral loads were decreased significantly in both lymph nodes and serum when compared
to the control (p<0,05). Finally, we can conclude that recombinant ORF2 antigen possessed
high immunogenicity and this antigen would be a potential candidate for recombinant vaccine
production against PCV2 in Viet Nam