ABSTRACT
Curraleiro Pé-Duro (CPD) cattle, a Brazilian local breed, are animals that are highly resistant to infectious and parasitic diseases. Strategies for the conservation of the breed and the genetic resistance to diseases should also consider the characteristics of the breed. The objective of this study was to analyze the diversity and population structure of the CPD breed using microsatellite markers and to correlate the serological profiles for causative agents of brucellosis, leptospirosis, neosporosis, leukosis, infectious bovine rhinotracheitis, and bovine viral diarrhea. DNA samples of 608 bovines were amplified and genotyped using 28 microsatellite markers for breed characterization. The genotypes were assigned to three clusters, indicating a substructure population related to the geographic distance. The observed heterozygosity was lower than that expected in most loci, and fixation index (Fst) in the subpopulation values ranged from 0.03073 (ETH3) to 0.402 (INRA63) on cluster 1, from 0.00 (INRA32) to 0.39359 (INRA63) on cluster 2, and from 0.00 (INRA32) to 0.28483 (TGLA53) on cluster 3. The Brucella spp., Neospora caninum, and Bovine Leukemia Virus frequencies were significantly different (p < 0.05) between clusters. The differences between the occurrences of diseases were not sufficient to indicate a genetic subpopulation with increased resistance to infections.
ABSTRACT
The present study aimed to assess the CD4, CD8 and Gamma delta T cells blood levels for Curraleiro Pé-duro, as well as the specific IFN-γ response after BCG vaccination using flow cytometry. The specific immune response against BCG was also evaluated by tuberculin skin test, performed before and 45 days after the vaccination. For comparison purposes, the same parameters were investigated on Nellore calves, an exotic bovine with resistance previously demonstrated. Naturally, Curraleiro Pé-duro animals had greater levels of CD4, CD8 and Gamma delta lymphocytes (p<0.05). In response to vaccine, Curraleiro Pé-duro showed greater ability to respond specifically to BCG, generating resistance profile (Th1), evidenced by greater number of antigen specific CD4+ cells producing IFN-γ (p<0.05) and also higher tuberculin skin test reaction (p<0.05). Additionally, vaccinated Curraleiro Pé-duro calves had higher CD4 cells numbers than both Nellore control (p<0.05) and vaccinated groups (p<0.05). Curraleiro Pé-duro calves' higher basal lymphocytes blood level and stronger response in both IFN-γ and tuberculin skin test parameters probably play a positive role on protection/resistance to Mycobacterium bovis.
O presente estudo teve como objetivo avaliar níveis sanguíneos de células CD4, CD8 e células T gama-delta no sangue periférico de bezerros Curraleiro Pé-Duro, bem como a produção específica de IFN-γ por essas células em resposta à vacinação com BCG, através de citometria de fluxo. A resposta imune específica contra BCG também foi avaliada por teste tuberculínico, realizado antes e 45 dias após a vacinação. Para fins de comparação, os mesmos parâmetros foram investigados em bezerros da raça Nelore, uma raça bovina exótica com resistência demonstrado anteriormente. Naturalmente, animais da raça Curraleiro Pé-Duro apresentaram maiores níveis de CD4, CD8 e linfócitos gama-delta. Em resposta a vacina, Curraleiro Pé-duro mostrou maior capacidade de responder especificamente ao BCG, gerando perfil de resistência (Th1), evidenciado pelo maior número de células CD4+ específicas produtoras de IFN-γ e maior reação cutânea a por tuberculina. Os maiores níveis basais de linfócitos, maior produção de IFN-γ e reação cutânea à prova tuberculínica provavelmente desempenham um papel positivo na proteção/resistência ao Mycobacterium tuberculosis.
