Detection and sequence analysis of equine gammaherpesviruses from horses with respiratory tract disease in Turkey

The equid herpesvirus 2 (EHV-2) and 5 (EHV-5), identified agents of respiratory infections and keratoconjunctivitis cases in some equids, comprise a high degree of antigenic heterogeneity. Prevalence and genetic characterization of EHV-2 and EHV-5 strains from Turkey were investigated in this study. A total of 73 nasal swabs and 54 blood specimens were sampled from horses with respiratory tract diseases characterized by mucopurulent nasal discharge and occasional coughing. Overall, EHV-2- and EHV-5-specific DNA amplicons were obtained from 19.2% (14/73) and 21.9% (16/73) of horses tested by multiplex nested PCR. Sequences of EHV-2 and EHV-5 glycoprotein B (gB) gene were used in a phylogenetic analysis that included six EHV-2 and three EHV-5 isolates, which showed that the Turkish EHV-2 and EHV-5 strains have marked sequence divergence from European strains and from each other. Turkish EHV-2 isolates were divided into two distinct subdivisions, and a few isolates were located on a separate branch. This study provides the first epidemiological and phylogenetical report about EHV-2 and EHV-5 infections in Turkey.