An attempt to identify genetic markers of resistance or susceptibility to dermatophilosis in the zebu Brahman population of Martinique.

Dermatophilosis is a disease associated with the tick Amblyomma variegatum, and a genetic predisposition to the manifestation of symptoms has been demonstrated. Indeed, the Creole cattle of Guadeloupe constitute a population which is highly resistant to this disease, whereas the Brahman zebu cattle of Martinique seem very susceptible. However, in this Brahman population there is a gradient regarding the severity of symptoms depending on individuals. In several herds of these pure zebu Brahman, kept under the same farming conditions, we selected susceptible and resistant groups because of the simultaneous presence of animals affected or not by clinical dermatophilosis. In these animals we studied several highly polymorphic genetic systems such as haemoglobin, albumin, the BoLA Complex (class I and II) and the gamma S crystallin gene. Only exon 2 of the BoLA-DRB3 gene, investigated by PCR-RFLP technique, showed interesting polymorphisms. We have established a genotypic map showing at least 4 different alleles of which 1 seems particular to one animal susceptible to dermatophilosis. Before reaching any conclusion further investigations with more DNA samples of susceptible animals are needed.