Evaluation of the transcriptional status of host cytokines and viral genes in the trachea of vaccinated and nonvaccinated chickens after challenge with infectious laryngotracheitis virus (ILTV)

Authors: VAGNOZZI, ARIEL - Institute De Virologia; RIBLET, SYLVA - University Of Georgia; ZAVALA, GUILLERMO - University Of Georgia; ECCO, ROSELENE - Universidade Federal De Minas Gerais; Afonso, Claudio; GARCIA, MARICARMEN - University Of Georgia

Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2015
Publication Date: 6/20/2016
Publication URL: http://handle.nal.usda.gov/10113/62704
Citation: Vagnozzi, A., Riblet, S., Zavala, G., Ecco, R., Afonso, C.L., Garcia, M. 2016. Evaluation of the transcriptional status of host cytokines and viral genes in the trachea of vaccinated and nonvaccinated chickens after challenge with infectious laryngotracheitis virus (ILTV). Avian Pathology. 45(1)106:113 doi:10.1080/03079457.2015.1126804.

Interpretive Summary: Infectious laryngotracheitis (ILT) is a highly contagious respiratory disease of chickens, which provokes significant economic losses to the U.S. poultry industry due to moderate mortality, decreased egg production, weight losses, and/or predisposition to other respiratory avian pathogens. The virus that causes the disease begins a productive infection in the upper respiratory tract of susceptible chickens, including conjunctival and tracheal mucosa followed by the establishment of latent infection. Inflammatory responses to infection are crucial in the outcome of infection because they control viral replication, contribute to the pathology of the disease, and modulate adaptive immune responses. In order to develop better vaccines and better control strategies, it is important to understand the roles of the protective immunity induced by vaccination against this agent. Cytokines are key components of the immune response produced by cells of the immune system in response to microbes and antigens that are involved in the modulation of immune and inflammatory responses. Profiling cytokine genes transcriptional status of infected tissues is important to provide critical information to understand the role of immune responses in the control of this and other avian diseases. Here we describe the cytokine profile of infection with infectious laryngotracheitis vaccines in the trachea of immunized and non-immunized chickens.

Technical Abstract: Infectious laryngotracheitis (ILT) is a highly contagious respiratory disease of chickens, which causes severe production losses to the poultry industry worldwide. Control of the disease is based on biosecurity and vaccination, whereas, comprehension of the nature of the protective immunity induced by vaccination with live attenuated vaccines, as chicken embryo origin (CEO) vaccine, is very limited. In this work, the transcription of key host immune genes (IFN-gamma, IFN-ß, IL-1ß, IL-6, IL-8, IL-18, iNOS) and several viral transcripts were measured after challenge (with a virulent infectious laryngotracheitis virus [ILTV] strain) in both, vaccinated and non-vaccinated chickens. Transcription of IL-1ß, IL-6, IL-8, and IFN-ß were not elevated in immunized chickens indicating that pro-inflammatory or antiviral responses are not part of the adaptive immune response induced by CEO vaccination at early stages of the infection. However, the early increase of IFN-gamma transcripts and the lack of viral transcripts in the trachea of CEO vaccinated birds suggested that the IFN-gamma expression transcription is the result of a mature adaptive immune response induced by CEO vaccination.