Isolation and Molecular Characterization of Equine herpes virus-1 from Horses Localized in Giza Governorate, Egypt

Equine herpesvirus-1 (EHV-1) is endemic in many world areas, including Egypt with significant economic losses in the equine industry through causing a high fatality rate among foals associated with respiratory manifestations and abortion in pregnant mares. The present study conducted to investigate the isolation,, molecular characterization, and phylogeny of the circulating EHV-1 isolates among native breeds of horses in Giza governorate. A total of 72 samples (aborted foeti, fetal fluids, placenta, vaginal and nasal swabs) were inoculated into Vero cell culture. The DNA was extracted from the infected tissue culture and used for molecular identification by TaqMan real-time PCR (qRT-PCR), DNA amplification by conventional PCR, and DNA sequencing. The results showed successful isolation of 9 out of 72 tested samples  (12.5%) after the third passage in Vero cells with a characteristic cytopathic effect for EHV-1. The obtained results were confirmed by qRT-PCR. The positive samples were subjected to conventional PCR to amplify 869 bp of the glycoprotein B gene. Sequencing and phylogenetic analysis revealed that EHV-1 isolates were closely related to each other and those previously isolated from Egypt and the European EHV-1 strains. In conclusion, the molecular characterization and phylogeny analysis of the circulating EHV-1 improve the understanding of virus epidemiology in Egypt and implicate good control measures.