Bovine respiratory syncytial virus (BRSV) is a widespread cause of lower respiratory tract disease in cattle. Calves less than four months of age are often involved in outbreaks of respiratory disease. We evaluated the efficacy of a single intranasal dose of a bivalent modified live vaccine containing BRSV (Rispoval (R) RS+Pi3 Intranasal, Pfizer Ltd.) in three-week-old calves with and without maternal antibodies to BRSV Two experimental challenge studies were undertaken. In the first study, the time to onset of protection following vaccination was determined in three-week-old colostrum deprived (maternal antibody negative) calves. Calves were challenged at 5, 10 or 21 days after vaccination. Onset of immunity was demonstrated within 5 days after vaccination. After challenge, clinical signs were mostly mild and differences between vaccinated calves and controls were small but the duration of coughing (indicative of upper respiratory tract disease) was significantly shorter in the vaccinates challenged 10 days after vaccination (P = 0.0059) and the duration of hyperpnoea (indicative of lower respiratory tract disease) was significantly shorter in the vaccinates challenged 5 days after vaccination (P = 0.0253). In the second study, the efficacy of the vaccine was assessed in three-week-old calves with maternal antibodies to BRSV Vaccination significantly reduced BRSV nasal shedding after challenge 9 weeks post vaccination and a strong serological booster response was observed in the vaccinated calves following challenge. In addition, clinical signs of respiratory tract disease following challenge were less severe in the vaccinates than the controls with a lower number of mortalities in the vaccinated calves. It is concluded that a single intranasal dose of the bivalent modified live vaccine containing BRSV (Rispoval (R) RS+Pi3 Intranasal, Pfizer Ltd.) provided significant protection against BRSV shedding and disease in young calves both with and without maternal antibodies to BRSV.
|Journal||Cattle practice: The Journal of the British Cattle Veterinary Association|
|Publication status||Published - 2005|
- maternal antibodies
- dairy calves
- young calves