Induction of Antiviral Response Against Avian Infectious Laryngotracheitis Virus Infection

Abstract

Toll-like receptors (TLRs) recognize pathogen associated molecular patterns (PAMPs). The PAMPs that act as ligands for TLRs prompt downstream signalling leading to antimicrobial effects. However, the details of antiviral responses of lipotechoic acid (LTA) and CpG DNA, which act as ligands for TLR-2 and -21 respectively, elicited against avian viruses are scarce. We investigated whether in ovo delivery of LTA and CpG DNA induces antiviral responses against infectious laryngotracheitis virus (ILTV) infection in chickens. We found that in ovo delivery of these two ligands reduces ILTV infections in lungs pre- and post-hatch. However, only CpG DNA could reduce mortality and morbidity due to ILTV infection encountered post-hatch. The expression of IL-1β mRNA and increase of macrophage numbers in lungs were found to be correlates of observed antiviral responses. Thus, LTA and CpG DNA can be candidate TLR ligands worthy of further investigation for the control of ILTV infection in chickens.