Enhancement of systemic virus-specific T lymphocyte responses in pigs supplemented with algae-derived β-glucan.

Algae-derived β-glucan has been widely used as a feed additive in the swine industry. The supplementation of β-glucan aims to improve growth performance and modulate the immunity of pigs. However, the potential effects of supplementing β-glucan from algae on immune responses in pigs-specifically antigen-specific immunity-must be determined. In this study, the effects of algae-derived β-glucan supplementation on growth performance, virus neutralising antibody and virus-specific T lymphocytes responses were investigated in pigs. Piglets (n=112 per treatment) were assigned to three treatments including non-supplemented group (control), β-glucan 100 g/ton supplemented group (BG100), and β-glucan 200 g/ton supplemented group (BG200). In this study, production performance of pigs was not found to be different between the experimental groups. Pigs supplemented with β-glucan exhibited high levels of classical swine fever virus (CSFV)-specific producing T lymphocytes and neutralising antibody titer, compared to the control group. Interestingly, supplementation of β-glucan significantly enhanced porcine reproductive and respiratory syndrome virus (PRRSV)-specific interferon-gamma (IFN-γ) producing T lymphocytes, including CD4+, CD8+, and CD4+CD8+ T lymphocyte subpopulations. Moreover, PRRS modified live vaccine (MLV) viremia was reduced in earlier for β-glucan-supplemented pigs compared to the control group. The findings indicate that the algae-derived β-glucan possesses biological potential as an immunomodulatory substance to enhance antiviral immunity, which may contribute to disease resistance in pigs.