Genetic analysis of Toxocara cati (Nematoda: Ascarididae) from Guangdong province, subtropical China

Abstract

Toxocara cati (cat roundworm) is a common parasitic nematode that infects humans and other hosts, causing toxocariasis. Although its significance as a pathogen, the epidemiology, genetics and biology of T. cati remain poorly understand in China. In the present study, genetic variation in mitochondrial (mt) cytochrome c oxidase subunit 1 (cox1) gene and internal transcribed spacer (ITS) of rDNA region among T. cati in Guangdong province, subtropical China was examined. A portion of the cox1 (pcox1) and the complete ITS (ITS1 + 5.8S rDNA + ITS2) were amplified separately from individual worms by polymerase chain reaction (PCR) and amplicons were then subjected to sequencing from both directions. The length of the sequences of pcox1, ITS-1, and ITS-2 were 308 bp, 462 bp, and 335 bp, respectively. The intra-specific sequence variations within T. cati were 0–3.6% for pcox1, 0–2.4% for ITS-1, and 0–2.7% for ITS-2. However, the inter-specific sequence differences were significantly higher, being 8.6%, 10.7%, and 11.3% for pcox1, ITS-1, and ITS-2, respectively. Phylogenetic analyses based on the pcox1 sequences indicated that all the isolates in Guangdong province were in genus Toxocara, which confirmed that these parasites represent T. cati. The molecular approach employed provides a powerful tool for elucidating the epidemiology, genetics, and biology of zoonotic T. cati in China and elsewhere.

Keywords:

• Genetic variation
• mitochondrial DNA
• internal transcribed spacer
• Toxocara cati

Acknowledgements

This work was supported by the National Key Research and Development Program of China (Grant No. 2016YFD0501300) and the Scientific and Technological Programs of Guangdong Province (Grant no. 2014A020208099).

Ethical standards

The performance of this study was strictly according to the recommendations of the Guide for the Care and Use of Laboratory Animals of the Ministry of Health, China, and our protocol was reviewed and approved by the Research Ethics Committee of South China Agricultural University.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This work was supported by the National Key Research and Development Program of China (Grant No. 2016YFD0501300) and the Scientific and Technological Programs of Guangdong Province (Grant no. 2014A020208099).