Antibody response to glycoprotein E after bovine herpesvirus type 1 infection in passively immunised, glycoprotein E-negative calves

This study was conducted to determine whether young calves with maternal an tibodies against bovine herpesvirus type 1 (BHV-1) but without antibodies a gainst glycoprotein E (gE) can produce an active antibody response to gE af ter a BHV-1 infection. Five calves received at birth colostrum from gE-sero negative cows which had been vaccinated two or three times with an inactiva ted BHV-1, gE-deleted marker vaccine. After inoculation with a wild-type vi rulent strain of BHV-1, all the passively immunised gE-negative calves shed virus in large amounts in their nasal secretions. All the calves seroconve rted to gE within two to four weeks after inoculation and then had high lev els of gE antibodies for at least four months. The development of an active cell-mediated immune response was also detected by in vitro BHV-1-specific interferon-gamma assays. All the calves were latently infected, because on e of them re-excreted the virus spontaneously and the other four did so aft er being treated with dexamethasone. The results showed that under the cond itions of this work the gE-negative marker could also distinguish between p assively immunised and latently infected calves.