Molecular characterization and virulence of an alphaherpesvirus isolated from a BoHV1 gB-seropositive and gE-seronegative Italian buffalo

During a serological survey, 157 out of 681 unvaccinated buffaloes resulted seropositive for bovine alpha-herpesvirus 1 (BoHV1) glycoprotein B (gB) and seronegative for BoHV1 glycoprotein E (gE). These serologicalresults were generally expected in animals vaccinated with a BoHV1 gE-deleted vaccine but not in unvaccinatedanimals. Seroneutralization tests on 36 selected sera detected neutralizing antibody titers more than three timeshigher for BuHV1 than for BoHV1. In order to investigate the virus, one of these buffaloes was injected withdexamethasone, and from nasal and vaginal swabs collected at different time points, a ruminant herpesvirus wasisolated, characterized and also detected by PCR. Restriction enzyme analysis, sequencing and phylogenicanalysis of gB and gD genes showed that the virus was genetically similar but not identical to BuHV1 strain b6.Intranasal inoculation of the virus in a healthy seronegative buffalo resulted in a mild and transient upperrespiratory disease; the virus was isolated from clinical specimens and DNA was detected by PCR in nasal andvaginal swabs up to 9 days after infection. Further investigations should be aimed at sequencing the whole viralgenome and at evaluating the host-range of this virus. Specific tests are needed to discriminate infections bydifferent ruminant herpesviruses and to improve eradication programs of infectious bovine rhinotracheitis/in-fectious pustular vulvovaginitis in cattle.