Abstract
Cosignal molecules are cell surface molecules that transduce signals to other cells to modulate immune response positively (costimulate) or negatively (cosuppress). Costimulatory signals are key factors in determining whether T/B cells are capable of responding to specific antigens and ultimately mediating an appropriate immune response. In this study, the cDNA sequence containing the complete coding frame of the costimulatory molecule duck CD40 gene was cloned and reported for the first time, and its mediated antiviral innate immune was verified in vitro. Results suggested duck CD40 molecule plays an important role in the innate immune responsiveness against some viruses. These data will be beneficial for the further understand of the avian immune system.