The complete mitochondrial genome of capillariid nematodes (Eucoleus annulatus): A novel gene arrangement and phylogenetic implications.

Capillariid nematode is a group of endoparasites of vertebrates with a complex taxonomy, causing significant economic losses to poultry industry. The taxonomic status of the genus Eucoleus remained controversial for several decades. Mitochondrial (mt) DNA provides useful genetic markers for accurate identification of species, but complete mt genome sequences have been lacking for any Capillariid nematodes. In the present study, we decoded the complete mt genome of E. annulatus and examined its phylogenetic relationship with selected members of the class Enoplea nematodes. The circular mt genome of E. annulatus was 14,118 bp, encoded 37 genes with a single non-coding region and showed substantial gene rearrangements (especially tRNA genes) compared to other nematodes studied to date. The complete mt genome of E. annulatus showed a clear A + T bias in nucleotide composition. The number of A (5404) was approximately equal to T (5405) and the GC-skew was negative on average (-0.073). Phylogenetic analyses based on 18S rDNA placed Eucoleus spp. well apart from each other and supported the proposal that Eucoleus and Capillaria are two distinct genera. Similarly, Bayesian inference (BI) and Maximum likelihood (ML) phylogenies based on mtDNA sequences revealed that the family Capillariidae is more closely related to the family Trichuridae than to the family Trichinellidae. This is the first report of the complete mt genome of capillariid nematodes, and it will provide additional genetic markers for studying the molecular epidemiology, population genetics and systematics of capillariid nematodes and should have implications for the molecular diagnosis, prevention, and control of capillariosis in animals.

Capillariid nematodes in Brazilian turkeys, Meleagris gallopavo (Galliformes, Phasianidae): pathology induced by Baruscapillaria obsignata and Eucoleus annulatus (Trichinelloidea, Capillariidae)

The pathology induced in turkeys (Meleagris gallopavo) by two capillariid nematodes, Baruscapillaria obsignata and Eucoleus annulatus is described together with data on prevalences, mean infection and range of worm burdens. B. obsignata occurred with a prevalence of 72.5 percent in the 40 examined hosts in a range of 2-461 nematodes and a mean intensity of 68.6, whereas E. annulatus was present in 2.5 percent of the animals, with a total amount of five recovered parasites. Gross lesions were not observed in the parasitized birds. Lesions due to B. obsignata mainly consisted of the thickening of intestinal villi with a mild mixed inflammatory infiltrate with the presence of mononuclear cells and heterophils. The lesions induced by E. annulatus were represented by foci of inflammatory infiltrate with heterophils in the crop epithelium and esophagus of a single infected female. These are the first pathological findings related to the presence of capillariid worms in turkeys to be reported in Brazil so far. Capillaria anatis, although present, was not pathogenic to the investigated turkeys.