Chabertia erschowi (Nematoda) is a distinct species based on nuclear ribosomal DNA sequences and mitochondrial DNA sequences.
BACKGROUND
Gastrointestinal nematodes of livestock have major socio-economic importance worldwide. In small ruminants, Chabertia spp. are responsible for economic losses to the livestock industries globally. Although much attention has given us insights into epidemiology, diagnosis, treatment and control of this parasite, over the years, only one species (C. ovina) has been accepted to infect small ruminants, and it is not clear whether C. erschowi is valid as a separate species.


METHODS
The first and second internal transcribed spacers (ITS-1 and ITS-2) regions of nuclear ribosomal DNA (rDNA) and the complete mitochondrial (mt) genomes of C. ovina and C. erschowi were amplified and then sequenced. Phylogenetic re-construction of 15 Strongylida species (including C. erschowi) was carried out using Bayesian inference (BI) based on concatenated amino acid sequence datasets.


RESULTS
The ITS rDNA sequences of C. ovina China isolates and C. erschowi samples were 852-854 bp and 862 -866 bp in length, respectively. The mt genome sequence of C. erschowi was 13,705 bp in length, which is 12 bp shorter than that of C. ovina China isolate. The sequence difference between the entire mt genome of C. ovina China isolate and that of C. erschowi was 15.33%. In addition, sequence comparison of the most conserved mt small subunit ribosomal (rrnS) and the least conserved nad2 genes among multiple individual nematodes revealed substantial nucleotide differences between these two species but limited sequence variation within each species.


CONCLUSIONS
The mtDNA and rDNA datasets provide robust genetic evidence that C. erschowi is a valid strongylid nematode species. The mtDNA and rDNA datasets presented in the present study provide useful novel markers for further studies of the taxonomy and systematics of the Chabertia species from different hosts and geographical regions.
Guo-Hua
GH
Liu
Lei
L
Zhao
Hui-Qun
HQ
Song
Guang-Hui
GH
Zhao
Jin-Zhong
JZ
Cai
Quan
Q
Zhao
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China. xingquanzhu1@hotmail.com.
Xing-Quan
XQ
Zhu
D000818:Animals; D001483:Base Sequence; D002681:China; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D005819:Genetic Markers; D014644:Genetic Variation; D049751:Genome, Helminth / Q000235:genetics*; D054629:Genome, Mitochondrial / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012418:Ruminants; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013045:Species Specificity; D017206:Strongylida Infections / Q000469:parasitology*; D013320:Strongyloidea / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification
D018509:DNA, Helminth; D004272:DNA, Mitochondrial; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D005819:Genetic Markers