PregSure® BVD – eine neue inaktivierte BVD-Vakzine : Breite Kreuzneutralisation von europäischen BVDV-Typ-1- und -Typ-2-Stämmen und signifikante Verbesserung der Fertilität nach Testinfektionen

Salt, J.S.; Antonis, A.F.G.; Peters, A.R.; Brune, A.; Jahnecke, S.; Traeder, W.; Harmeyer, S.S.


Objective: Aim of the present study was to demonstrate the relevance of the vaccine strain of a new BVD vaccine, PregSure® BVD, for its use in Europe. Furthermore the vaccine¿s ability to protect from pregnancy losses due to an early infection with BVDV after artificial insemination was determined. Material and methods: The immune sera used in the in-vitro cross neutralisation were collected from 20 heifers three weeks after the completion of the primary vaccination schedule with PregSure® BVD (two vaccinations given 21 days apart). The BVDV cross-neutralising activity of these postvaccinal sera was tested by virus neutralisation employing a panel of different predominantly European BVDV type I and II strains. Furthermore, two fertility studies were carried out, where heifers between 14 and 39 months of age were primovaccinated with PregSure® BVD or left untreated as control, respectively. All animals had their oestrus cycles synchronised and were artificially inseminated. Four days after the initial artificial insemination and again three days later, all animals of experimental group 1 were challenged intranasally with two heterologous noncytopathic BVDV type I strains, whereas animals from group 2 received a type I and a type II BVDV strain. Sixty-nine to 72 days after the challenge, all dams were slaughtered and their foetuses collected. Differences in pregnancy rates between the vaccinated and the control group were assessed and then analysed using Fisher¿s Exact Test. Results: Heifers vaccinated with a novel inactivated BVDV vaccine containing a cytopathic BVDV type I strain 5960, were shown to have serum neutralising antibody titres between 5.5 to 12.3 log2 against all BVDV strains tested, three weeks after the completion of their primary vaccination course. In the first fertility experiment, pregnancy rates assessed 69-72 days after a double challenge with two different BVDV type I strains were 95.5% in the vaccinated group versus only 40.9% in the control group. A level of cross-protection against a severe BVDV type II challenge was shown in the second experiment with pregnancy rates of 47.6% in the vaccinated group and only 4.4% in the control group. Conclusions and clinical relevance: The broad cross neutralising activity shown in this study demonstrates the relevance of the vaccine strain 5960 for use in Europe. Furthermore as shown with significantly improved pregnancy in the two fertility experiments, PregSure® BVD vaccinated heifers are protected against fertility losses caused by acute BVDV infections.