Selecting the Best Combination of Adjuvant and the Delivery Vehicle for Optimizing the Th1 and Th2 Biased Responses of NDV Live Vaccine in Indigenous Aseel Chicken

This study aimed at the evaluation of the efficacy of TLR ligands (viz. Poly I:C, Lipopolysaccharide and CpG:ODN) as vaccine adjuvants in combination with a suitable carrier (oil-in-water emulsion, normal saline solution, or alum) by studying the expression profile of cytokines belonging to Th1 and Th2 biased immune systems.

Whole blood was collected from 108 birds that were divided into 9 different experimental groups: 3 TLR ligands each with 3 delivery vehicles. Th1 (IFN-y) and Th2 (IL4) biased cytokines were detected by qPCR followed by ELISA. Both the results showed the highest level of IL4 (Th1 biased) with LPS and the highest level of IFNy (Th1 biased) with CpG-ODN. Uneven TLR expression was detected from day 3 onwards till day 21 but ligands and delivery vehicles administered along with NDV vaccine did not show significant influence on the immune response.

It is evident that the TLR-3, 4 and 9 expressions increase following exposure to the respective ligands. Hence, TLR ligands can be used as reliable adjuvants in NDV vaccine. The expression of the Th2 biased cytokine IL4 mRNA and Th1 biased cytokine Interferon-gamma was found to be the highest on day 3 in the LPS+NSS group and on day 21 in CpG-ODN+Alum group, respectively. The findings of the real-time PCR were supported to some by the ELISA.