Assessment of cellular and mucosal immune responses in chicks to Newcastle disease oral pellet vaccine (D58 strain) using qPCR.

To assess the cell mediated and mucosal immune responses in chicks to Newcastle disease vaccine, expression levels of certain genes encoding cytokines and chemokines were quantified by q-PCR. The utility of cytokine and chemokine gene expression profile in estimating the cell mediated and humoral immune response has been established. The cell mediated immune response was assessed by quantifying the IFN-γ gene expression in splenocytes and compared with colorimetric blastogenesis assay. The mucosal immune response was assessed by quantifying the expression of IL-8, IL1-β, MIP1-β, K60 and K203 in the intestinal cells and compared with IgA ELISA. On 14th day post vaccination, the expression of IFN-γ was upregulated by 12-folds in the Group I, which have received oral pellet vaccine and fourfolds in the Group II where birds have received live thermostable vaccine as occulonasal instillation. 3 and 7 days after receiving booster, the same cytokine gene was upregulated by 12-folds and 27-folds respectively in the Group III, where birds have received live thermostable ND vaccine as priming vaccine and oral pellet vaccine as booster. On 21st day post vaccination the expression of IL-8 was upregulated by 42.8-folds in Group I and 3.3-folds in the Group II. The expression of IL-1β was upregulated by eightfolds on 3rd day post vaccination and 23-folds on 21st day post vaccination in Group I. The expression of macrophage inflammatory protein-1β (MIP-1β) was upregulated by 16-folds in Group I and 70-folds in Group II on 14th day post vaccination. No significant change in expression of chemokine genes K60 and K203 in vaccinated birds. The results were comparable with the results of conventional tests and proved the utility of qPCR in estimating the cellular and mucosal immune responses.