Recombinant porcine interferon alpha enhances the humoral and cellular immune responses to porcine transmissible gastroenteritis virus inactivated vaccine in piglets

Abstract

In this study, the effect of recombinant porcine interferon alpha (rPoIFNα) on porcine transmissible gastroenteritis virus inactivated vaccine (TGEV IV) in terms of immunological augmentation was examined. Seven experimental piglet groups, including PBS group, rPoIFNα group, inactivated vaccine (IV) alone group, 4.0x104 U rPoIFNα+IV group, 2.0x105 U rPoIFNα+IV group,1.0x106 U rPoIFNα+IV group, 5.0x106 U rPoIFNα+IV group, were divided. The piglets in each group received a secondary vaccination at 28 days following the initial immunization. By using the ELISA assay, neutralization assay, MTT assay, and flow cytometry, we measured anti- TGEV-specific antibody expressions, neutralization antibodies, as well as lymphocyte proliferation index (Stimulation index, SI), specific IL-4 and IFN-γ production, and T cell subpopulations (CD3+, CD4+, and CD8+). Piglets injected with IV supplemented with rPoIFNα at 1.0x106 U or 5.0x106 U developed significantly higher anti-TGEVspecific and neutralizing antibodies compared to those treated with IV alone. IV therapy with rPoIFNα at 1.0x106 U or 5.0x106 U can boost cellular immunity against TGEV by increasing SI, IL-4, IFN-γ, and the ratio of CD3+, CD4+, and CD8+ cell subgroups. The IV+5.0x106 U rPoIFNα group showed a considerably larger immune increase than the IV+2.0x105 U rPoIFNα group, suggesting that it works in a dose-dependent manner. Therefore, rPoIFNα at 1.0x106 U or 5.0x106 U enhances the immune response against TGEV IV and may function as an immune stimulant.

Keywords

• cellular immune response
• humoral immune response
• inactivated vaccine (iv)
• porcine transmissible gastroenteritis virus (tgev)
• recombinant porcine interferon alpha (rpoifnα)