The Molecular Detection of Equine Herpesviruses 2 and 5 in Genital Swabs From Clinically Normal Thoroughbred Mares in South Korea

Abstract

Equine herpesvirus (EHV) 2 and equine herpesvirus 5 (EHV-5) have been getting attention as potential causative pathogens of reproductive disorders in horses. Equine herpesviruses 2 and 5 are widespread among horses and have been detected in various samples including nasal swabs, blood, and ocular swabs. However, the detection of these pathogens in genital swabs has not been determined. The aims of this study were to determine the positive rate of EHV-2 and EHV-5 DNA in genital swabs taken from clinically normal mares and to define the genetic diversity of these EHV-2 and EHV-5 DNA sequences by comparing them to previously reported EHV-2 and EHV-5 nucleotide sequences. Four hundred and thirty genital swabs from clinically normal mares were tested for EHV-2 and EHV-5 by glycoprotein B (gB)-specific polymerase chain reaction. From 430 genital swabs, 10 (2.3%) contained EHV-2 DNA, and 11 (2.6%) were positive for EHV-5. The sequences of the EHV-2 and EHV-5 gB gene were used in phylogenetic analyses and revealed that the Korean EHV-2 and EHV-5 strains have a marked genetic diversity, with a nucleotide sequence identity among the strains that ranged from 92.57% to 100% and from 98.07% to 100% for EHV-2 and EHV-5, respectively. The degree of similarity between Korean strains and those recovered from horses elsewhere ranged from 88.13% to 100% for EHV-2 and 95.96% to 100% for EHV-5. Further studies are now required to determine if the presence of EHV-2 and EHV-5 DNA is associated with reproductive disorders in clinically affected horses.