[Effect of maternal antibodies on vaccine-induced immune responses in Holstein calves]

ABSTRACT This research aimed to evaluate the effect of colostral antibodies (ABs) on the humoral immune response induced by vaccination in Holstein calves. Twenty-four calves were randomly assigned into four groups: G1 - vaccinated on D14 and D44 (n= 6); G2 - on D90 and D120 (n= 5); G3 - on D180 and D210 (n= 8); Control: unvaccinated (n= 5). Commercial vaccine (Cattle Master Gold FP5+L5® - Zoetis, Brazil) was administered subcutaneously (5mL). Virus neutralization test (VN) was performed at the time of vaccination, booster and 30 days after booster to determine AB titers. No differences were observed between control and G1 or G2 for seropositive frequencies and ABs titers (P≥ 0.05). G3 showed higher AB production than control for BoHV-1 (P< 0.01), BRSV (P< 0.01) and BPIV-3 (P= 0.02) after booster (D240). Overtime analysis also exhibited increase in AB titers in G3 (P≤ 0,05). Bronchopneumonia was identified in the control group (n= 4/5) between 80-135 days of life. The colostral and vaccinal immunity presented inversely proportional profiles, with higher production of ABs at 6 months of age. Due to the precocity of respiratory disease further studies are required to clarify the role of cellular immune response to vaccination in face of maternal ABs.