Single Radial Hemolysis assay (SRH) to evaluate immunity protection and factors that affect the immunity level against Equine Influenza Virus infection in horses in Uruguay

Abstract

The equine influenza virus subtype H3N8 has been considered the most important respiratory pathogen of horses, due to its highly contagious nature and its rapid spread among susceptible animals. It has been shown that the degree of protection deter­mined by inactivated vaccines, is closely related to the level of circulating antibodies against the virus hemagglutinin Equine influenza. The aim of this study is to determine the susceptibil­ity of sport horses in Uruguay to infection by equine influenza virus by measuring antibodies SRH (single radial hemolysis), and study its association with factors such as age, horse breed, sex, and vaccination history. 1532 equine sera of different horse breed, sex and vaccination status by SRH were processed, and giving missing values only 1390 was considered for the statis­tical analysis. To observe the behavior of the observed frequen­cies of the SRH univariate analysis was performed Low cover­age of vaccination against Equine Influenza in sport horses was observed (23%) and a very low level of virological and clini­cal immunity (27% and 35% respectively) against infection of H3N8 virus test determined by SRH test. Increased susceptibil­ity to infection by the H3N8 virus was observed in horses with­out updated vaccination, Arab and Quarter mile breed horses, horses younger than 2 years old, and in castrated males horses.