Genotipic variability study of Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae) from different geografic regions of Brazil. / Estudo da variabilidade genotípica de Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae) de diferentes regiões geográficas do Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The taxonomic status of ticks of the Rhipicephalus sanguineus group is difficult to be determined by phenotypic methods and has been object of frequent revisions and ongoing debate. The differentiation of species within this group has clinical importance, especially in veterinary medicine due to transmission of different pathogens. The objective of this study was to evaluate de genetic variability of Rhipicephalus sanguineus from different geografic regions of Brazil and fill in some gaps in the species study. This work was conducted in the laboratories of: Ixodology of the W. O. Neitz station for parasitologic research, Molecular Biology and Acarology, of the Departamento de Parasitologia Animal, Instituto de Veterinária, da Universidade Federal Rural do Rio de Janeiro; and in the laboratories of: Genetic and Biochemistry, and Genome of EMBRAPA Agrobiologia (RJ). Mitochondrial DNA (mt-DNA) fragments of R sanguineus from Espírito Santo (ES), Goiás (GO), Pará (PA), Rondônia (RO), Mato Grosso do Sul (MS), Rio de Janeiro (RJ) e Rio Grande do Norte (RN) were compared. The results showed that fasting larvae, preserved in ethanol, from the different localities presented genotipic variability considering the 12S and 16S mt-rDNA genes. To 12S, the Espírito Santo strain presented the highest genetic diversity in comparison with the other brazilian strains; to 16S, the distinction can be given to the Rio de Janeiro strain, which presented the highest divergence values in regarding the other strains. The intraspecific variability detected between the isolates ranged from 0 to 6.6% regarding the 12S gene and from 0 to 2.7% regarding the 16S. On the other hand, a strong genetic relationship was detected between brazilian isolates and asian R. sanguineus (0-5.8% of variability for 12S, and 0-1.3% for 16S) and between the brazilian strains and african Rhipicephalus turanicus (2.2-7.6% of difference to 12S) while R. sanguineus populations from Argentina and Uruguai appeared to be related to French R. sanguineus (identic 12S sequences); considering 16S, R. sanguineus from Israel presented moderate distance from the brazilian isolates (3.6-5.8%). These results showed that the differences between these brazilian isolates are great and to a certain extent greater than should be expected between some of them, and that the systematic of R. sanguineus ticks from Latin America as much as of countries of other continents should be better and more studied. Wide variations, such as these might account for the reported worldwide differences in several biological parameters in this species.

ASSUNTO(S)

variabilidade genotípica rhipicephalus sanguineus brasil. medicina veterinaria genotipic variability

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