Bovine herpesvirus-1 (BHV-1) - a re-emerging concern in livestock: a revisit to its biology, epidemiology, diagnosis, and prophylaxis

Bovine herpesvirus-1 (BHV-1) is known to cause several diseases worldwide. It is a double-stranded DNA virus consisting of 33 structural proteins out of which 13 are associated with the envelope. Based on genomic analysis and viral peptide patterns, BHV-1 virus can be divided into several subtypes like BHV-1.1, BHV-1.2, and BHV-1.3. However, all subtypes are antigenically similar. The symptoms of the related diseases are mainly non-life-threatening but have a rather wide host range that limits animal trade. The different modes of transmission as unique feature of this virus and the tendency to cause infection in the early age with latency development in trigeminal and sacral ganglion cause huge economic losses around the world. The virus also affects endangered bovine species like mithun (Bos frontalis) and yak (Poephagus grunniens). The disease can be diagnosed by using conventional procedures (like cell culture, immune-histopathology, and enzyme-linked immunosorbent assay (ELISA)) as well as highly sensitive modern techniques (like nested PCR and southern hybridization) with the virus neutralization test regarded as gold standard. With the currently available diagnostic tests it is not possible to identify animals which have a latent BHV-1 infection. Different types of modern and conventional vaccines are available for immunoprophylaxis. Inactivated vaccines are not as efficacious as modified live virus (MLV) vaccines. Marker vaccines allow the distinction between vaccinated and naturally infected animals. In this review the present status of BHV-1 around the world will be addressed besides the current knowledge with regard to its biology, epidemiology, diagnosis, and prophylaxis.