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Correlation between the resistance character to, dermatophilosis in Zebu Brahman cattle and certain BoLA class I and class II MHC haplotypes

Maillard J.C., Martinez D., Bensaïd A.. 1994. Animal Genetics, 25 (2) : n. 2 suppl.. International Conference on Animal Genetics. 24, 1994-07-23/1994-07-29, Prague (Tchèque, République).

One hundred and twenty Brahman cattle from different locations in Martinique (FWI) reared under different environmental conditions were followed over three years including rainy seasons and checked for clinical signs of dermatophilosis. Sera from these animals were tested by ELISA for antibodies against Dermatophilus congolensis in order to confirm that cattle had been in contact with the pathogen. On the basis of this epidemiological study, 14 animals were classified as resistant to dermatophilosis (serological positive but showing no clinical signs throughout the survey) ; they belong to herds in which the prevalence of the disease ranged from 25 to nearly 100%. Sixteen animals classified as highly susceptible displayed the more severe characteristic skin lesions and died during the course of the survey. These 30 selected animals were typed for MHC class I antigens using a microlymphocytotoxic test. MHC class II genes were typed using the PCR-RFLP technique on the exon 2 of the BoLA DRB3 gene. Seventeen alleles were found according to pattems provided by the restriction enzymes used. A particular sequence (EIAY) at amino-acid positions 66 /67/74/78 located in the antigen recognition site (ARS) was found in all 14 animals classified as resistant and 10 of them displayed also the class I BoLA-A8 specificity. On the other hand only 3 out of the 16 susceptible animals showed simultaneously the BoLA-DRB3 EIAY sequence and the BoLA-A8 specificity Interestinglg a serine at position 30 of the ARS was found in 8 of the susceptible animals and was absent from all resistant animals. These results show a strong correlation between resistance to dermatophilosis and MHC haplotypes comprising BoLA-A8 specificity and BoLA-DRB3 genes which encode a EIAY sequence at positions 66/67/74/78 of the ARS. (Résumé d'auteur)

Mots-clés : système mhc; immunité; résistance aux maladies; maladie bactérienne; dermatophilus; zébu; martinique; zébu brahman

Thématique : Génétique et amélioration des animaux; Maladies des animaux

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