Dietary administered purified β-glucan of edible mushroom (Pleurotus florida) provides immunostimulation and protection in broiler experimentally challenged with virulent Newcastle disease virus

Abstract Background To study the immunomodulatory and protective role of dietary administered purified β-glucan obtained from edible mushroom (Pleurotus florida) in commercial broiler chicken, experimentally challenged with virulent Newcastle disease virus (NDV) on 7th day post treatment. Mushroom glucan (MG) at 15 mg/kg feed (group A) and MG at 30 mg/kg feed (group B) was administered to broiler birds for 20 days keeping control birds (group C) with a normal diet throughout. After 7 days post treatment, three groups of birds (n = 4, in each case) were challenged with virulent NDV. The immunological parameters were assessed to observe the protective efficacy of MG. Results When compared to the treatment regime, it was observed that in all the cases, group B birds showed higher immune-cellular and humoral responses in terms of enhanced immune-effector activities of blood leucocytes and intestinal intra-epithelial leucocytes and antibody production besides protection against NDV challenge than the others. After NDV challenge, 100% mortality was observed in control birds within 4 days, whereas in treated birds 50% and 75% protection of challenged birds was observed in group A and group B birds, respectively. The superoxide anion production by blood leucocytes of group A (0.641 ± 0.01) and group B (0.721 ± 0.01) birds were significantly higher than the control birds (0.283 ± 0.04) when assessed on 4th day post challenge. Group A (27.33 ± 1.20 μl and 25.33 ± 2.02 μl) and group B (33.66 ± 0.33 μl and 32.66 ± 0.33 μl) birds showed higher in vitro nitrite production by peripheral blood mononuclear cells (PBMC) and intestinal intra-epithelial leucocytes (iIEL), respectively, than the control (14.00 ± 0.57 μl and11 ± 0.57 μl) after challenge with virulent ND virus. In vitro lymphoproliferation (expressed as stimulation index) was significantly high in PBMC and iIEL of group A (0.371 ± 0.02 and 0.295 ± 0.02) and group B (0.428 ± 0.01 and 0.314 ± 0.01), respectively, than control (0.203 ± 0.01 and 0.135 ± 0.01) on 4th day of NDV challenge. The phagocytic activity of iIEL of the treated group birds showed higher values (24% and 32%) than the control group (14%). The haemagglutination inhibition (HI) titre was also observed higher in treated groups (group A, average HI titre 256, and group B, average HI titre 512) than control (HI titre, 32). Both groups (A&B) of birds were produced in vitro IFN-γ by PBMC and iIEL. Conclusion It is advisable to use 30 mg MG/kg feed in broiler birds to provide immunostimulation and for better output in terms of disease protection at least against ND virus.