Modified-Live Bovine Viral Diarrhea Virus (B VDV) Type la Vaccine Provides Protection Against Fetal Infection after Challenge with either Type lb or Type 2 BVDV

摘要

The objective of two bovine viral diarrhea virus (BVDV) fetal protection studies was to determine if vaccination with modified-live virus (MLV) BVDV type la (BVDVla) vaccine would protect fetuses from infection with BVDV type 2 (BVDV2) or type Ib (BVDVlb) virus. The experimental vaccine administered to the cows and heifers had the minimum antigen load dose of MLV BVDVla and the full (commonly marketed) antigen dose of infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI3), bovine respiratorysyncytial virus (BRSV), and Leptospira Canicola-Grippotyphosa-Hardjo-Ictero-haemorrhagiae-Pomona (Lepto-CGHIP) bacterin. In Trial A, 25 pregnant vaccinated cows and heifers and 10 pregnant unvaccinated controls were challenged with BVDV2. In Trial B, 25pregnant vaccinated cows and heifers and eight pregnant unvaccinated controls were challenged with BVDVlb. In both trials, fetuses were obtained by Cesarean section, which was performed after approximately 150 days of gestation (range 148-174 days), andpresence or absence of fetal BVDV infection was determined. All control fetuses were infected with BVDV. In Trial A, all fetuses (N = 25) of vaccinated dams were free of BVDV infection. In Trial B, one cow did not have a fetus at 150 days of gestation; of 24 fetuses, 23 were negative for BVDV and one fetus was positive for BVDV. In contrast to previous studies, these results suggest that vaccination with MLV BVDVla vaccine will significantly reduce fetal infection following challenge with BVDV2.