Expression profile of MHC class-II trans activator gene in pig immunized with recombinant virus like particles encoding porcine circovirus 2d.

Porcine circovirus type 2d (PCV2d) is one of the predominant genotypes associated with porcine circovirus-associated diseases, which highlights the need for effective vaccination strategies. This study assessed the expression profile of the major histocompatibility complex class II transactivator (CIITA) gene in pigs immunized with recombinant PCV2d virus-like particles (VLPs). Recombinant PCV2d capsid protein was expressed in insect cells and self-assembled into VLPs, which were further used to immunize piglets. Peripheral blood mononuclear cells were analyzed for CIITA expression by qRT-PCR and interferon-gamma (IFN γ) production by ELISA. Following PCV2d VLP immunization, CIITA expression increased over time, peaked on day 21, and was associated with elevated IFN-γ secretion. A significant positive correlation between CIITA expression and IFN γ levels was detected in pooled analyses. These findings demonstrate that PCV2d VLPs endorse Th1-biased immune responses and further enhance the CIITA-mediated antigen presentation, supporting their potential as an effective vaccine platform against PCV2d.