ABSTRACT
Objective: The objective of the present study was to identify Trichostrongylus species by molecular analysis and also phylogenetic relationships of Trichostrongylus species by mitochondrial Cytochrome c oxidase subunit 1 (Cox1) gene in Guilan province, northern Iran. Methods: Abomasum and duodenum contents of 144 livestock were collected from sheep, goats, and cattle in Guilan province. Morphological survey was performed for initial screening. Total DNA was extracted, and the partial region of Cox1 gene was amplified and sequenced. Genetic diversity was calculated and phylogenetic analysis of the data on nucleotide sequence was conducted by MEGA7 software. Results: Three species of Trichostrongylus including T. colubriformis, T. vitrinus, and T. axei were identified by morphological characteristics. The genetic divergence within the species in the present study was observed for T. axei (0-2.5%), T. colubriformis (0.77%), and T. vitrinus (0%). The mean inter-species difference between the three species of Trichostrongylus obtained in this study was 14.4-15.4%. Conclusion: The Cox1 sequences of the members of Trichostrongylus spp. were highly variable and this could be used as a valuable measure to achieve a proper assessment on biodiversity. Sequence data generation from other species of Trichostrongylus will be needed to reconstruct the phylogenetic relationships of this genus of nematodes.
Subject(s)
Trichostrongyloidea , Trichostrongylus , Animals , Cattle , Sheep , Electron Transport Complex IV , Iran , PhylogenyABSTRACT
BACKGROUND: This study was carried out to investigate the prevalence and analyze the molecular characteristics based on the internal transcribed spacer (ITS) 2 region of the ribosomal RNA (RNA) gene of trichostrongylid nematodes in different ruminants from Guilan province, northern of Iran. METHODS: The gastrointestinal tracts of 144 ruminants including 72 cattle, 59 sheep, and 13 goats were collected from an abattoir in Guilan province during July to September 2018. After isolation the helminths, male specimens were identified based on morphological parameters. PCR and partial sequencing of the ITS2 fragment were conducted. After phylogenetic analysis, the intraspecific and interspecific differences were calculated. RESULTS: The prevalence of total infections with the nematodes was 38.9, 74.6 and 84.6% among cattle, sheep and goats, respectively. Eleven species of trichostrongylid nematodes including Haemonchus contortus, Marshallagia marshalli, Trichostrongylus axei, T. colubriformis, T. vitrinus, Ostertagia trifurcata, Teladorsagia circumcincta, Marshallagia occidentalis, O. lyrata, O. ostertagi, and Cooperia punctate were recovered from the ruminants. The most prevalent trichostrongyloid nematodes in cattle, sheep and goats were O. ostertagi (26.4%), M. marshalli (64.4%) and T. circumcincta (69.2%), respectively. Phylogenetic tree was discriminative for Trichostrongylidae family, while phylogenetic analysis of the ITS2 gene represented low variations and no species identification of Haemonchidae and Cooperiidae families. CONCLUSIONS: This study suggests the high prevalence and species diversity of trichostrongyloid nematodes in different ruminants, indicating the importance of implement antiparasitic strategies in north regions of Iran. As well, this study showed that the ITS2 fragment is not a discriminative marker for Haemonchidae and Cooperiidae families, and investigation of other genetic markers such as mitochondrial genes would be more valuable for better understanding of their phylogenetic relationships.
