Antigenic and molecular characterization of a herpesvirus isolated from a North American elk

Objective-To determine whether a herpesvirus isolated from the semen of a N orth American elk was related to bovine herpesvirus 1 (BHV-1). Sample Population-Semen from 1 healthy bull elk and 2 subtypes of BHV-1 (BH V-1.1 and BHV-1.2). Procedures-A virus with cytopathic and electron microscopic characteristics consistent with an alpha-herpesvirus was isolated from elk semen, using fe tal bovine kidney cells. Cross-neutralization assays were performed with an tisera against BHV-1 and the elk herpesvirus (ElkHV). Restriction endonucle ase digests of ElkHV DNA were compared with digests of BHV-1.1 and BHV-1.2 DNA. A portion of the ElkHV DNA polymerase gene was amplified with consensu s primers by use of the polymerase chain reaction and sequenced. Sequence w as compared with known sequences of other herpesviruses. An immunoperox ida se monolayer assay was used to determine reactivities of 22 BHV-1-specific monoclonal antibodies (mAb) against ElkHV. In vitro neutralizing activities of the reactive mAb were determined by use of a microneutralization assay. Results-Results of cross-neutralization assays indicated that ElkHV was ser ologically related to BHV-1, Endonuclease digestion of ElkHV DNA generated fragments that were distinct from those of BHV-1. Nucleotide sequencing con firmed that ElkHV is an alphaherpesvirus closely related to but distinct fr om BHV-1. Six of 22 BHV-1-specific mAb reacted against ElkHV; 2 of these 6 also neutralized in vitro infectivity of ElkHV. Conclusions and Clinical Relevance-ElkHV is antigenically and genetically d istinguishable from BHV-1. However, the viruses are serologically related a nd share at least 6 antigenic determinants, one of which is a major neutral izing determinant. (Am J Vet Res 2000;61:1614-1618).