Administration of TLR7 agonist, resiquimod, in different types of chicken induces a mixed Th1 and Th2 response in the peripheral blood mononuclear cells

•We demonstrated resiquimod (R848) induced immune response in three chicken breeds.•Expression of IFN-γ, IL-1β and TLR7 was high in Kadaknath birds.•Expression of IFN-β was maximum in White Leghorn birds.•The expression of iNOS and IL-4 was high in broiler birds at 24 h post-injection.•Overall, resiquimod (R848) induced a mixed Th1 and Th2 response in the chicken.

This study evaluated the variation in immune response in peripheral blood mononuclear cells (PBMCs) of broiler, White Leghorn (WL) and Kadaknath breeds of chicken following administration of TLR7 agonist, resiquimod (R-848). Expression of different immune related genes viz., interferon-β (IFN-β), IFN-γ, IL-1β, IL-4, TLR7 and iNOS was assessed by quantitative real time PCR over a period of 24 h. The results indicated that there was a significant up-regulation in the relative expression of immune response genes post R-848 administration (P < 0.01). In conclusion, the transcriptional expression of IFN-β, IFN-γ, IL-1β, IL-4, iNOS and TLR7 genes in the PBMCs was significantly up-regulated over 24 h in broiler, WL and Kadaknath breeds of birds after the administration of R-848. Overall, R-848 induced a mixed Th1 and Th2 response in PBMCs of chicken origin ex vivo.