Genetic variability among Hymenolepis nana isolates from different geographical regions in China revealed by sequence analysis of three mitochondrial genes.

Hymenolepis nanais a common tapeworm that parasitizes in the small intestine of rodent animals and humans. The present study examined the sequence diversity of three mitochondrial (mt) genes namely NADH dehydrogenase subunits 5 (nad5), small subunit ribosomal RNA (rrnS), and ATPase subunit 6 (atp6) ofH. nanafrom mice in different geographical regions of China. A part of thenad5 (pnad5), completerrnS andatp6 genes were amplified separately from individualH. nanaisolates using polymerase chain reaction (PCR) and then sequenced. The sequences of pnad5,rrnS, andatp6 were 710 bp, 704–711 bp, and 516 bp in length, respectively. The A + T contents of the sequences were 70.1–73.5% (pnad5), 70.1–71.7% (rrnS), and 76.6–77.9% (atp6). Sequence variation withinH. nanawas 0–1.4% foratp6, 0–1.7% forrrnS, and 0–0.7% for pnad5. The inter-specific sequence differences betweenH. nanaandHymenolepis diminutawere significantly higher, which was 31.6–31.7% (pnad5), 16.1–17.6% (rrnS), and 26.5–27.1% (atp6). Phylogenetic analysis based on the combined three sequences using the maximum parsimony (MP) method supported thatH. nanais a species complex or “cryptic” species. These findings demonstrated clearly the usefulness of the three mtDNA sequences for population genetics and systematic studies ofH. nanaof human and animal health significance. [ABSTRACT FROM AUTHOR]