Development of in-house Taqman qPCR assay to detect equine herpesvirus-2 in Al-Qadisiyah city

Abstract

EHV-2 is distributed in horses globally. It is clustered within gamma-herpesvirus subfamily and percavirus genus. EHV-2 infection has two phases: latent and lytic. In the later, EHV-2 mainly associated with respiratory and genital symptoms. However, in the quiescent phase of infection, EHV-2 stay dormant in the host till viral reactivation. Our previous study has showed that EHV-2 can be harboured by equine tendons, suggesting that leukocytes possibly carrying EHV-2 for the systemic dissemination. So far, numerous PCR protocols have been performed targeting the gB gene. However, this gene is heterogenic. Therefore, there is a need to develop a quantitative diagnostic approach to detect the quiescent EHV-2 strains. To do this, Taqman qPCR assay was developed to quantify the virus. This was performed by targeting a highly conserved gene known as DNA polymerase (DPOL) gene using constructed plasmid as a standard curve calibrator. The obtained results showed an infection frequency of 33% in which the EHV-2 load reached 6647 copies/100 ng DNA whereas the minimum load revealed as 2 copies/100 ng DNA. The median quantification was found as 141 copies/ 100 ng DNA. Establishment of a credited qPCR assay to quantify EHV-2 could be helpful in the control of the disease.