Isolation, identification and chemical inactivation of infectious laryngotracheitis virus for use as a vaccine candidate

Infectious laryngotracheitis (ILT) is a poultry respiratory disease associated with considerable mortality in chicken and decreasing egg production. Vaccination along with biosecurity measures are considered as the main strategy for ILT control. This study was aimed to evaluate the potency of an inactive ILT vaccine candidate derived from a local ILTV isolate. The isolated virus was characterized and treated with various chemicals and their concentrations. The virus infectivity was entirely abolished by treatment of 3 mM binary ethylene imine following 16 h incubation. The immune response of inactivated ILTV suspension with adjuvans was evaluated in both SPF chickens (experiment-I) and Hyline pullets (experiment-I I). Efficacy of the inactivated and live ILT vaccines combination was compared. The results of experiment-I showed that the inactivated antigen induced specific antibody titers against ILTV. In experiment-II, despite the increase in serum antibody level administration of the inactivated antigen alone did not offer sufficient protection. The full protection was found in chickens that received the combination regimen. We conclude that simultaneous administration of the inactivated and live ILT vaccines was efficient for induction of immunity against ILTV.

Automated summary

Infectious laryngotracheitis (ILT) is a respiratory disease in poultry with high mortality rates and decreased egg production. Vaccination and biosecurity measures are key in controlling ILT. This study evaluated an inactivated ILT vaccine candidate derived from a local ILTV isolate, finding that combined administration of inactivated and live ILT vaccines was most effective in inducing immunity against ILTV.