Fetal protection against bovine viral diarrhea virus types 1 and 2 after the use of a modified-live virus vaccine.
The objective of this study was to demonstrate the efficacy of a modified-live virus (MLV) vaccine in protecting fetuses from infection with type 1 or type 2 Bovine viral diarrhea virus (BVDV) when pregnant heifers were challenged at approximately 170 d of gestation with noncytopathic field isolates. The 83 pregnant heifers had been bred naturally 4 wk after vaccination. Fetuses were collected 60 d after BVDV type 2 challenge, and newborn calves were collected before colostrum intake after BVDV type 1 challenge. Protection was determined by measuring the serum neutralizing (SN) antibody response in the fetus or calf and by virus isolation from thymus, lung, spleen, and kidney tissue samples. There was a measurable SN antibody response to BVDV in all the fetuses and calves of the control heifers, which had received a placebo vaccine. However, only 4 of 22 calves and 7 of the 28 fetuses of the MLV-vaccinated heifers demonstrated SN antibody after BVDV challenge. Type 1 BVDV was isolated from tissue samples of 5 of the 12 calves of control heifers and none of 22 calves of the MLV-vaccinated heifers challenged with type 1 BVDV. Type 2 BVDV was isolated from tissue samples of 17 of the 18 fetuses of the control heifers and 2 of the 28 fetuses of the MLV-vaccinated heifers challenged with type 2 BVDV. The results of this study demonstrate that the MLV vaccine reduces the fetal infection rate by at least 82% for BVDV type 1 and by 75% for BVDV type 2 when heifers are exposed to highly fetotrophic BVDV at 170 d of gestation.
Xue
Wenzhi
W
Biological Research and Development, Intervet/Schering Plough Animal Health, De Soto, Kansas 66018, USA. wenzhi.xue@sp.intervet.com
Mattick
Debra
D
Smith
Linda
L
Maxwell
Jon
J
D000818:Animals; D000831:Animals, Newborn; D000914:Antibodies, Viral / Q000097:blood; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000276:immunology* / Q000517:prevention & control*; D002417:Cattle; D030241:Diarrhea Virus 1, Bovine Viral / Q000276:immunology*; D030242:Diarrhea Virus 2, Bovine Viral / Q000276:immunology*; D005260:Female; D005333:Fetus; D009500:Neutralization Tests / Q000662:veterinary; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control / Q000662:veterinary / Q000821:virology; D011897:Random Allocation; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000276:immunology
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines