Efficacy of a combination viral vaccine for protection of cattle against experimental infection with field isolates of bovine herpesvirus-1.
OBJECTIVE
To determine whether a combination viral vaccine containing a modified-live bovine herpesvirus-1 (BHV-1) would protect calves from infection with virulent field strains of BHV-1 for weeks or months after vaccination.


METHODS
Randomized controlled trial, performed in 2 replicates.


METHODS
63 weaned 4- to 6-month-old crossbred beef calves seronegative for antibody against BHV-1.


METHODS
Calves were randomly allocated to 1 of 2 treatment groups. Control calves (n = 10/replicate) received a combination modified-live mixed viral vaccine without BHV-1, and treatment calves (20 and 23/replicate) received a combination modified-live mixed viral vaccine containing BHV-1. Each group was challenged via aerosol with 1 of 2 field strains of BHV-1, 30 days after vaccination in replicate 1 and 97 days after vaccination in replicate 2. After challenge, calves were commingled in 1 drylot pen. Clinical signs, immune responses, and nasal shedding of virus were monitored for 10 days after challenge, after which the calves were euthanatized and tracheal lesions were assessed.


RESULTS
Vaccination stimulated production of BHV-1-specific IgG antibody that cross-neutralized several field and laboratory strains of BHV-1. Challenge with both field strains of BHV-1 resulted in moderate to severe respiratory tract disease in control calves. Treatment calves had significantly fewer signs of clinical disease, shed less BHV-1, had less or no weight loss after challenge, and had fewer tracheal lesions than control calves for at least 97 days after vaccination.


CONCLUSIONS
Administration of the combination modified-live BHV-1 vaccine yielded significant disease-sparing effects in calves experimentally infected with virulent field strains of BHV-1.
Ellis
John A
JA
Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.
Gow
Sheryl P
SP
Goji
Noriko
N
Jones
Clinton
C
Workman
Aspen
A
Henderson
Gail
G
Rhodes
Carrie
C
Alaniz
Glenn
G
Meinert
Todd R
TR
Tucker
Cassius M
CM
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002417:Cattle; D004279:DNA, Viral; D007242:Herpesvirus 1, Bovine / Q000145:classification* / Q000276:immunology*; D007241:Infectious Bovine Rhinotracheitis / Q000517:prevention & control*; D013997:Time Factors; D014764:Viral Proteins; D014765:Viral Vaccines / Q000276:immunology*; D017201:Virus Shedding
D000914:Antibodies, Viral; D004279:DNA, Viral; D014764:Viral Proteins; D014765:Viral Vaccines