Vaccination and acute phase mediator production in chickens challenged with low pathogenic avian influenza virus; novel markers for vaccine efficacy?

Abstract

Methods to determine vaccine efficacy of low pathogenic avian influenza (LPAI) isolates are limited in poultry because experimental infections with LPAI virus in specific pathogen free chickens rarely causes clinical disease. The most commonly used method to compare LPAI vaccine efficacy is to quantify viral shedding after challenge, but it is time and labor intensive. Therefore, we sought alternative methods to demonstrate vaccine efficacy, and examined whether vaccination of chickens affected the production of acute phase mediators in serum (e.g., alpha-1 acid glycoprotein, ovotransferrin and prostaglandin E2) following challenge with homologous (A/Chicken/Hidalgo/232/94 H5N2) or heterologous (A/Chicken/167280-4/02 H5N3) LPAI isolates. Vaccination significantly reduced oropharyngeal viral shedding, and serum concentration of acute phase mediators, regardless of whether homologous or heterologous challenge viruses were used. Examining the expression of acute phase mediators post-challenge may serve as additional markers to determine LPAI vaccine efficacy in chickens.