Development of a rapid and sensitive polymerase chain reaction assay for detection of bovine herpesvirus type 1 in bovine semen.

We developed a polymerase chain reaction (PCR) assay to detect bovine herpesvirus type 1 (BHV-1) in bovine semen. Since bovine semen contains components that inhibit PCR amplification, a protocol was developed to purify BHV-1 DNA from bovine semen. To identify failures of PCR amplification, we used an internal control template that was coamplified by the same PCR primers. When separated fractions of BHV-1-contaminated semen were analyzed by the PCR, we found that more than 90% of the BHV-1 DNA was present in a pooled fraction consisting of seminal fluid, nonsperm cells, and virus adsorbed to spermatozoa. By using this fraction, three to five molecules of BHV-1 DNA in 50 microliters of bovine semen could be detected. A pilot study to compare this PCR assay with the routinely used virus isolation method showed that this PCR assay is 2- to 100-fold more sensitive. In addition, the results of the PCR assay are available in 1 day, whereas the virus isolation method takes 7 days. Therefore, the PCR assay may be a good alternative to the virus isolation method.