-Herpesviruses have mainly co-evolved with their hosts for millions of years. Consequently, different related host species may have been infected by various genetically related herpesviruses. Illustrating this concept, several ruminant alphaherpesviruses have been shown to form a cluster of viruses closely related to bovine herpesvirus 1 (BoHV-1): namely bovine herpesvirus 5, bubaline herpesvirus 1, caprine herpesvirus 1, cervid herpesviruses 1 and 2 and elk herpesvirus 1. These viruses share common antigenic properties and the serological relationships between them can be considered as a threat to BoHV-1 eradication programmes. BoHV-1 is a herpesvirus responsible for infectious bovine rhinotracheitis, which is a disease of major economic concern. In this article, the genetic properties of these ruminant alphaherpesviruses are reviewed on a comparative basis and the issue of interspecific recombination is assessed. The pathogenesis of these infections is described with emphasis on the host range and crossing of the host species barrier. Indeed, the non bovine ruminant species susceptible to these ruminant alphaherpesviruses may be potential BoHV-1 reservoirs. The differential diagnosis of these related infections is also discussed. In addition, available epidemiological data are used to assess the potential of cross-infection in ruminant populations. A better knowledge of these ruminant alphaherpesvirus infections is essential to successfully control infectious bovine rhinotracheitis.

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The control of infectious bovine rhinotracheitis induced by bovine herpesvirus 1 (BoHV-1) requires sensitive and specific diagnostic assays. As BoHV-1 is antigenically and genetically related to four other alphaherpesviruses of ruminants-namely, BoHV-5, caprine herpesvirus 1 (CpHV-1), cervine herpesvirus 1 (CvHV-1) and CvHV-2-diagnostic tests able to discriminate BoHV-1 from these related viruses are needed to avoid misdiagnosis, especially because some of these viruses are able to cross the species barrier. In this study, murine monoclonal antibodies (MAbs) specific for BoHV-1, BoHV-5, CpHV-1, CvHV-1, and CvHV-2 were produced with the aim of setting up an immunofluorescence assay able to discriminate between these related herpesviruses. Produced MAbs were selected for their viral specificity by enzyme-linked immunosorbent assay and indirect immunofluorescence staining of virus-infected cells. Radioimmunoprecipitation characterization of the selected MAbs revealed that four of them are directed against glycoprotein C (gC) and one of them is directed against gD of these related viruses. The obtained results demonstrate that the antibodies produced allow an unambiguous discrimination of each of the four alphaherpesviruses related to BoHV-1.

Two strains of caprine herpesvirus type 1 (CpHV-1) were isolated after the experimental reactivation of two seropositive goats in Spain. Viral DNA from these isolates was compared with DNA from bovine herpesvirus type 1 and CpHV-1 reference strains by restriction endonuclease analysis. The two Spanish isolates were closely related but could easily be distinguished from each other and from the reference strains.

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