Sequence variation in two mitochondrial DNA regions and internal transcribed spacer among isolates of the nematode Oesophagostomum asperum originating from goats in Hunan Province, China.

The present study examined sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1), and internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) among Oesophagostomum asperum isolates from goats in Hunan Province, China. A portion of the cox1 (pcox1), nad1 (pnad1) genes and the ITS (ITS1+5.8S rDNA+ITS2) rDNA were amplified by polymerase chain reaction (PCR) separately from adult O. asperum individuals and the representative amplicons were subjected to sequencing from both directions. The lengths of pcox1, pnad1 and ITS rDNA were 366 bp, 681 bp and 785 bp, respectively. The A+T contents of gene sequences were 71.5-72% for pcox1, 73.7-74.2% for pnad1 and 58-58.8% for ITS rDNA. Intra-specific sequence variations within O. asperum were 0-1.6% for pcox1, 0-1.9% for pnad1 and 0-1.7% for ITS rDNA, while inter-specific sequence differences among members of the genus Oesophagostomum were significantly higher, being 11.1-12.5%, 13.3-17.7% and 8.5-18.6% for pcox1, pnad1 and ITS rDNA, respectively. Phylogenetic analyses using combined sequences of pcox1 and pnad1, with three different computational algorithms (Bayesian inference, maximum likelihood and maximum parsimony), revealed distinct groups with high statistical support. These findings demonstrated the existence of intra-specific variation in mtDNA and rDNA sequences among O. asperum isolates from goats in Hunan Province, China, and have implications for studying molecular epidemiology and population genetics of O. asperum.

[Cytotoxin adhesion and invasiveness of Campylobacter jejuni from children with diarrhea: assay and correlation with clinical manifestations].

Some potentially pathogenic properties have been identified for Campylobacter jejuni in vitro. The cell-free filtrates of 42 strains, (28 isolated from clinical cases of diarrhea, 12 from domestic animals and 2 from healthy children) were investigated. 30 of the 42 were cytotoxin producers, and the strains from clinical cases were more frequent than those from other sources (P less than 0.05). Meanwhile, 25 of the 42 strains exhibited adhesion and invasiveness with HeLa cell line in vitro. It is surprising that the 2 strains from healthy children were all negative in cytotoxin production, adhesion and invasiveness in vitro. Analysis of the virulence correlation with clinical manifestations indicated that the pathogenic significance of cytotoxin, adhesion and invasiveness should be adequately evaluated.