Untersuchung zur Wirksamkeit der Impfung mit einem BVDV1-Lebendimpfstoff sowie mit einem inaktivierten BVDV1-Impfstoff gegen eine BVDV2-Testinfektion

The aim of the study was to determine the cross protection against a challenge infection with a highly virulent BVDV2-strain (strain 890) after a single vaccination with a BVDV1 live vaccine (Vacoviron®/Mucosiffa®) or a repeated vaccination with a BVDV1 inactivated vaccine (Mucobovin®). Fifteen calves were allotted into one control- and two vaccine groups. The Mucobovin®-group was vaccinated at days 61 and 29, and the Vacoviron®-group at day 61 before challenge infection. The calves were monitored by clinical observation using the point-scheme of Cortese (behaviour, haemorrhages, respiratory symptoms and diarrhoea), and by haematological (leukocyte and platelet count), virological (virus isolation in cell culture and RT-PCR) and serological parameters. The animals vaccinated with the live vaccine displayed the best immunity of the three groups. The Mucobovin® group also developed immunity, but clinical signs were more pronounced than in the Vacoviron® group. The control group exhibited significant clinical changes in contrast to the vaccine groups. Four of the five control animals and one calf in the Mucobovin®-group were leukopenic. After the challenge infection, virus was only isolated from the control animals. RT-PCR was positive on 20 samples (over a 12 days period) in the control-group, and in six samples (over a five days period) in the Mucobovin® group and remained negative in the Vacoviron® vaccinated animals. The control animals sero-converted after the challenge infection, the Mucobovin® group after the second vaccination and the Vacoviron® animals after the single vaccination. Antibody-titers in all groups increased markedly after the challenge infection. The study shows that the vaccination with a BVDV1 vaccine can produce an adequate protection against a BVDV2 infection.