Genetic variability among Trichuris ovis isolates from different hosts in Guangdong Province, China revealed by sequences of three mitochondrial genes

Abstract

This study examined sequence variation in three mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (cox1), NADH dehydrogenase subunit 5 (nad5) and cytochrome b (cytb), among Trichuris ovis isolates from different hosts in Guangdong Province, China. A portion of the cox1 (pcox1), nad5 (pnad5) and cytb (pcytb) genes was amplified separately from individual whipworms by PCR, and was subjected to sequencing from both directions. The size of the sequences of pcox1, pnad5 and pcytb was 618, 240 and 464 bp, respectively. Although the intra-specific sequence variations within T. ovis were 0–0.8% for pcox1, 0–0.8% for pnad5 and 0–1.9% for pcytb, the inter-specific sequence differences among members of the genus Trichuris were significantly higher, being 24.3–26.5% for pcox1, 33.7–56.4% for pnad5 and 24.8–26.1% for pcytb, respectively. Phylogenetic analyses using combined sequences of pcox1, pnad5 and pcytb, with three different computational algorithms (maximum likelihood, maximum parsimony and Bayesian inference), indicated that all of the T. ovis isolates grouped together with high statistical support. These findings demonstrated the existence of intra-specific variation in mtDNA sequences among T. ovis isolates from different hosts, and have implications for studying molecular epidemiology and population genetics of T. ovis.

Keywords::

• Trichuris ovis
• genetic variability
• mitochondrial DNA
• phylogenetic analysis

Declaration of interest This work was supported, in part, by the Program for Outstanding Scientists in Agricultural Research, the Open Funds of State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences (Grant Nos. SKLVEB2011KFKT004, SKLVEB2011KFKT010, SKLVEB2010KFKT009 and SKLVEB2010KFKT010) and the Yunnan Provincial Program for Introducing High-level Scientists (Grant No. 2009CI125). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.