Avaliação da imunidade passiva em bezerros nascidos de vacas imunizadas com vacina contra rotavírus

Passive immune response in calves fed colostrum from immunized and nonimmunized cows by anti-rotavirus vaccine was monitored. Titers of antibodies were determined by immunoenzymatic assay in blood and colostrum sampled at parturition day from 26 Holstein cows as well as in blood from their calves collected at 0, 24, and 48 hours and seven, 14, 21, and 28 days after birth. In serum and colostrum, IgG, IgG1, and IgG2 antibody titers were higher in vaccinated animals; however, this increase was only significant in colostrum. The calves fed colostrum from vaccinated cows showed higher IgG, IgG1, IgG2, IgA, and IgM isotypes titers after the ingestion of colostrum, being evidenced significant increase only for IgG2 titers. Positive samples for rotavirus were detected in both experimental groups since seven days after birth. Results showed that maternal vaccine failed to protect effectively the calves from natural infections by rotavirus, though it increased the anti-rotavirus antibody titers in vaccinated animals, but was not capable to impair the occurrence of rotaviruses in the calves fed colostrum from immunized cows.