Genetic variation in mitochondrial genes of the tick Haemaphysalis flava collected from wild hedgehogs in China.

The tick Haemaphysalis flava (Acari: Ixodidae) is an important ectoparasite, which causes direct damage to their hosts and also acts as a vector of various infectious disease agents in China. Despite its significance, the epidemiology, genetics and biology of H. flava has not been studied in detail. In the present study, the genetic variation in three mitochondrial (mt) DNA regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 and 4 (nad1 and nad4), was examined in H. flava ticks collected from wild hedgehogs in China. A portion of cox1 (pcox1), nad1 (pnad1) and nad4 (pnad4) genes were PCR amplified from individual H. flava ticks and the amplicons were sequenced. The length of the sequences of pcox1, pnad1 and pnad4 were 849, 285 and 626 bp, respectively. The intra-specific sequence variation within H. flava was 0-0.4% for pcox1, 0-0.4% for pnad1 and 0-0.3% for pnad4. However, the inter-specific variation was significantly higher, 12.5-14.3%, 13.6-24.8% and 14.8-19% for pcox1, pnad1 and pnad4, respectively. Phylogenetic analysis based on Maximum likelihood (ML) method using the combined target mt gene sequences confirmed that all isolates of Haemaphysalis were H. flava. The molecular approach employed in this study provides a tool for further elucidating the molecular diversity of H. flava in China and elsewhere in Asia.