A live bovine herpesvirus-1 marker vaccine is not shed after intramuscular vaccination

It should be established, whether animals vaccinated intramuscularly (IM) with a live Bovine herpesvirus type 1 (BHV-1) marker vaccine become viremic and/or excrete vaccine virus with nasal discharge. Five cattle, seronegative for BHV-1, were vaccinated with an overdose of the vaccine (Bovilis IBR marker live) via the IM route. Nasal swabs and blood samples were taken at regular intervals and tested for BHV-1 in a virus infectivity assay. In addition, a polymerase chain reaction (PCR) specific for BHV-1 DNA was performed on the blood samples. BHV-1 neutralizing antibody titres were determined in the sera taken prior to the vaccination and four weeks after immunisation. AIl animals were successfully vaccinated as judged by the development of BHV-1 neutralising antibodies. However, all nasal swab samples were tested negative for vaccine virus, and all blood samples were found negative for BHV-1 vaccine virus and BHV-1 specific DNA. From these data it can be concluded that the vaccine virus was not excreted with nasal discharge after IM vaccination and that the vaccinated animals did not have a detectable viremia. Therefore, it is recommended to apply the tested BHV-1 marker live vaccine by the IM route in situations where it is undesirable that the vaccine virus is excreted.