title: The live attenuated bovine viral diarrhea virus components of a multi-valent vaccine confer protection against fetal infection.
abstract: Fetal infection with bovine virus diarrhea virus (BVDV) causes severe economic loss and virus spread in cattle. This study investigated the ability of modified live BVDV I and II components of a commercially available modified live virus (MLV) vaccine (Breed-Back FP 10, Boehringer Ingelheim Vetmedica Inc.) to prevent fetal infection and abortion, and therefore the birth of persistently infected animals. Heifers immunized with vaccine 4-8 weeks before insemination showed no adverse effects. All vaccinated animals had seroconverted to BVDV 4 weeks after immunization. Pregnant heifers were divided into two vaccination and two control groups and challenged with type I or II BVDV on days 60-90 of gestation. Seroconversion, clinical signs, immunosuppression, viremia, mortality, abortion rate, and fetal infection were studied. Post-challenge, 6/11 (type I challenged) and 8/11 (type II challenged) vaccinated heifers were free from clinical signs of BVD. Post-challenge clinical signs noted in the vaccinated groups were mild to moderate, while all unvaccinated controls had clinical signs ranging from moderate to severe. Viremia was not detected post-challenge in any of the vaccinated heifers. However, 100% of the controls were BVDV viremic on at least 1 day post-challenge. One of 22 vaccinated heifers had transient leukopenia, whereas 2/8 and 6/7 unvaccinated heifers in control groups I and II, respectively, had transient leukopenia. Type II BVDV infection led to abortion or death in 86% of unvaccinated heifers. The corresponding vaccinated group showed no deaths or abortions. All control group fetuses were infected with BVDV. The test vaccine gave 91% (type I BVDV challenged) and 100% (type II BVDV challenged) protection from fetal infection. This vaccine is safe and effective against fetal infection, abortion (type II BVDV) and the birth of persistently infected animals.
mesh_terms: D000034:Abortion, Veterinary / Q000517:prevention & control / Q000821:virology; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000097:blood; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000517:prevention & control* / Q000635:transmission; D002417:Cattle; D030241:Diarrhea Virus 1, Bovine Viral / Q000276:immunology; D030242:Diarrhea Virus 2, Bovine Viral / Q000276:immunology; D001908:Diarrhea Viruses, Bovine Viral / Q000276:immunology*; D005260:Female; D005315:Fetal Diseases / Q000517:prevention & control / Q000662:veterinary*; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control / Q000662:veterinary*; D007970:Leukopenia / Q000517:prevention & control / Q000662:veterinary; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control / Q000662:veterinary*; D011897:Random Allocation; D016896:Treatment Outcome; D014613:Vaccines, Attenuated; D017778:Vaccines, Combined / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology; D014766:Viremia / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary
chemical_list: D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D017778:Vaccines, Combined; D014765:Viral Vaccines