Evaluation of protection against virulent bovine viral diarrhea virus type 2 in calves that had maternal antibodies and were vaccinated with a modified-live vaccine.
OBJECTIVE
To evaluate the efficacy of an adjuvanted modified-live bovine viral diarrhea virus (BVDV) vaccine against challenge with a virulent type 2 BVDV strain in calves with or without maternal antibodies against the virus.


METHODS
Challenge study.


METHODS
23 crossbred dairy calves.


METHODS
Calves were fed colostrum containing antibodies against BVDV or colostrum without anti-BVDV antibodies within 6 hours of birth and again 8 to 12 hours after the first feeding. Calves were vaccinated with a commercial modified-live virus combination vaccine or a sham vaccine at approximately 5 weeks of age and challenged with virulent type 2 BVDV 3.5 months after vaccination. Clinical signs of BVDV infection, development of viremia, and variation in WBC counts were recorded for 14 days after challenge exposure.


RESULTS
Calves that received colostrum free of anti-BVDV antibodies and were vaccinated with the sham vaccine developed severe disease (4 of the 7 calves died or were euthanatized). Calves that received colostrum free of anti-BVDV antibodies and were vaccinated and calves that received colostrum with anti-BVDV antibodies and were vaccinated developed only mild or no clinical signs of disease.


CONCLUSIONS
Results indicated that the modified-live virus vaccine induced a strong protective immune response in young calves, even when plasma concentrations of maternal antibody were high. In addition, all vaccinated calves were protected against viral shedding, whereas control calves vaccinated with the sham vaccine shed virus for an extended period of time.
Zimmerman
Alicia D
AD
Rural Technologies Inc., 1008 32nd Avenue, Brookings, SD 57006, USA.
Boots
Robin E
RE
Valli
Jennifer L
JL
Chase
Christopher C L
CC
D000818:Animals; D000831:Animals, Newborn; D000914:Antibodies, Viral / Q000008:administration & dosage / Q000097:blood*; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000517:prevention & control*; D002417:Cattle; D003126:Colostrum / Q000276:immunology; D030242:Diarrhea Virus 2, Bovine Viral / Q000276:immunology*; D005260:Female; D007112:Immunity, Maternally-Acquired; D011897:Random Allocation; D014613:Vaccines, Attenuated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*; D014774:Virulence
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines