Sequence Analysis of Seven Equine Herpes Type 1 Viruses Circulating In Non- vaccinated Arabian and Foreign Horses In Egypt

Background: Equine herpes virus 1 (EHV-1) has a significant economic impact on the equine industry. It is a highly contagious pathogen, mainly transmitted by inhalation of aerosols of virus-laden respiratory secretions especially with the high population during equestrian events. Reactivation of virus in non-symptomatic, latently (silently) infected horses is the main cause of circulation of such virus in horses. Aim: Molecular characterization of the circulating strains of Equine herpes viruses in the Egyptian equestrian clubs. Methods: In the present study, molecular characterization of circulating EHV-1 viruses among horses of equestrian clubs in Egypt was carried out. Sixty-two samples of whole blood with anticoagulant were collected and screened for EHV-1 using nested PCR that amplifies the conserved fragment of glycoprotein B gene (ORF 33), followed by sequencing and phylogenetic analysis. Results: The study revealed that 19% of our samples were positive to EHV-1 and phylogenetic analysis showed that the Egyptian EHV-1 isolates were more than 99% similarity to European abortogenic isolates (EHV-1 strains: Army 183 and Suffolk/48/2013). Indeed, the analysis reports that these viruses are circulating in both Arabian and foreign horses in Egypt. Conclusion: The nested PCR is an appropriate technique for the detection of EHV-1 present in blood of a latently, or silently infected horses. The application of this nested PCR is considered to be a rapid diagnostic tool for use in veterinary laboratories. Thus it will enhance the detection and characterization of the circulating EHV-1 in Egypt. Control strategy for EHV-1 viruses in vaccinated and non-vaccinated animals needs to be addressed.