Use of real-time polymerase chain reaction to detect bovine herpesvirus 1 in frozen cattle and buffalo semen in India.

Bovine herpesvirus 1 (BoHV-1) infection in cattle and buffalo makes these animals life-long carriers of the virus which is intermittently excreted in semen. In the present study, a real-time polymerase chain reaction (PCR) was validated to screen frozen semen from cattle and buffalo for BoHV-1 by amplification of the gB gene of the virus. Analysing the intra- and inter-test variability, the assay was found to be highly reproducible. High sensitivity (100%) and specificity (90.04%) of this real-time PCR assay was recorded in comparison to virus isolation. Extended frozen semen samples from 574 cattle and buffalo bulls that were seropositive to infectious bovine rhinotracheitis (IBR) tested by real-time PCR indicated that 1.97% semen batches from cattle and 3.36% batches of buffalo semen were positive for BoHV-1. The real-time PCR protocol will be useful for screening large numbers of semen samples from IBR-seropositive cattle and buffalo bulls as the test is less time consuming and several batches of semen can be tested with ease compared to virus isolation in cell culture.