554Pesq. Vet. Bras. 30(7): 554-558, julho 2010 RESUMO.-[Esquemas de vacinação e cepa bacteriana influenciam na resposta sorológica contra o carbúnculo sintomático em bezerros de corte.] Foi avaliada a resposta sorológica de bezerros de corte submetidos a diferentes esquemas de vacinação contra o carbúnculo sintomático, empregando-se como antígenos duas cepas distintas de Clostridium chauvoei: uma oficial (MT) e a outra uma cepa de campo. Os animais (n=60) foram randomizados em quatro grupos (G1, G2, G3 e Controle) e submetidos a três protocolos distintos de vacinação com um produto comercial polivalente. O G1 foi primovacinado aos 4 meses de idade e recebeu o reforço após desmama (8 meses de idade The serological response of beef calves was evaluated with different vaccination regimens against blackleg, using an official strain (MT) and a field-collected strain of Clostridium chauvoei as antigens. Sixty calves were randomly allocated to four different groups and were submitted to distinct vaccination protocols with a commercial polyvalent vaccine. Group G1 was first vaccinated at four months of age and a booster shot was given after weaning, at eight months. Group G2 was given the first dose at eight months and a booster shot 30 days later. Group G3 was vaccinated only once at eight months and the control group was not vaccinated. These alternative vaccination regimens were proposed in an effort to adequately protect cattle under open-field farming conditions. Serological evaluations were made by Elisa at 4, 8, 9 and 10 months of age. Both groups receiving booster shots had a significantly increased serological response 30 days later. However, the serum IgG levels against C. chauvoei were significantly higher in the calves that were first vaccinated at four months. At 10 months, the two booster shot groups (G1 and G2) had similar serological responses, while the calves that were treated with a single dose of vaccine at weaning (G3) had a response that was similar to that of the control group. The serological response of the calves was significantly inferior at several of the evaluation times when the field strain of the bacteria was used as a challenge antigen instead of the official MT strain. The serological response of calves that are vaccinated twice was found to be satisfactory, independent of the first injection being made at four or eight months of age. It was also concluded that it would be useful to include local bacterial strains in commercial vaccine production.

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