Development of a subunit vaccine containing recombinant chicken anemia virus VP1 and pigeon IFN-γ

• A subunit vaccine against chicken infectious anemia was co-administered with pigeon IFN-γ.
• This vaccine induced a high IgG titer and maintained the hematocrit values at normal levels after a CAV challenge.
• Increased chicken IFN-γ cytokines production indicated induction of cell-mediated immunity.
• Co-immunization with pigeon IFN-γ may result in adjuvant activity on a VP1 subunit vaccine.

Chicken anemia virus (CAV) is a severe threat to the chicken industry and causes heavy economic losses worldwide. In this study, we evaluated the immune response and protective efficacy provided by a subunit vaccine containing recombinant VP1 (rVP1) and pigeon interferon-γ (rPiIFN-γ). Results indicated that rPiIFN-γ enhanced humoral immunity elicited by rVP1 as early as 10 day after primary immunization and reach the high titer after secondary immunization. When compared to chickens immunized with rVP1, inactivated vaccine, chickens immunized with rVP1 + rPiIFN-γ showed faster and higher levels (p < 0.05) of antibody titer. The CAV challenge result showed that the rVP1 + rPiIFN-γ vaccine prevent the reducing of hematocrit values in comparison with the rVP1 or inactivated groups. The relative fold inductions of mRNA expression of Th1-type (IFN-γ), but not Th2-type (IL-4) cytokines in splenocytes isolated from chickens immunized with rVP1 + rPiIFN-γ were significantly higher than those of the rVP1 or inactivated vaccine groups. In conclusion, our study found that rPiIFN-γ can enhance both humoral and cellular immunity elicited by an rVP1 vaccine. The rVP1 + rPiIFN-γ vaccine may provide a new strategy vaccine against CAV in chicken.