Molecular Identification and Phylogenetic Analysis of Ascarids in Wild Animals

Abstract

Ascarid nematodes are the most common and harmful nematodes parasites in animals. By analyzing genetic variation, this study explores the genetic and phylogenetic relationship among ascarids from 11 different hosts. This study collected ascarid samples from the feces of nine animal species in Changsha Ecological Zoo of Hunan Province and two animal kinds in the College of Veterinary Medicine of Hunan Agricultural University. The mitochondrial gene (pcox1) and ribosomal ITS sequences were amplified, sequenced, and analyzed by PCR to identify the species of the samples. The phylogenetic tree was constructed based on two genes (cox1 and ITS) by the Neighbor-joining method, and the phylogenetic relationship was analyzed. The sequencing results showed that the sequence lengths of pcox1 and ITS genes in the samples were 441 bp and 838–1,177 bp, respectively. The difference rates were 0.00–1.70% in pcox1 gene and 0.00–7.30% in ITS gene. Phylogenetic analysis showed that ascarid worms from the white lion, Northeast tiger, South China tiger and cheetah were identified as Toxascaris leonina. Ascarids from the zebra were identified as Parascaris equorum, while those from chicken and peacocks were identified as Ascaridia galli. Ascarids of wolf and dog origin were Toxocara canis, the snake ascarids belonged to Ophidascaris filaria, and the bear ascarids belonged to Baylisascaris transfuga. There was a significant gap between different kinds of ascarid worms. We found that these two mitochondrial genes pcox1 and ITS showed a common characteristic that the intraspecific differences were significantly smaller than the interspecific differences, confirming that these two genes could be used as interspecific genetic markers for molecular identification of different ascarids origins. The intraspecific variation rate of the ITS gene was higher than that of pcox1, indicating that ITS can also be used in the genetic research of Ascaris species development. This study revealed the genetic evolution and phylogeny of ascarids in wild animals, and our results will help prevent and control ascarids in wild animals.

Diversity of helminths with zoonotic potential and molecular characterization of Toxocara canis infecting domestic dogs from locations of Amazon and Atlantic Forest Brazilian biomes

“…The nucleotide composition of A+T for pnad1 ranged from 64.2 to 64.8%. Values close to A+T contents for mitochondrial (mtDNA) genes have been reported in other studies, and the results are compatible for nematodes (Li et al, 2008;Chen et al, 2022).…”

Characterisation of the mitochondrial genome and phylogenetic analysis of Toxocara apodemi (Nematoda: Ascarididae)

“…The ITS sequences of T. apodemi (Accession no. OR231233) were first determined in the present study; it was 957 bp in length and had 80.94% identity to that of T. canis in GenBank (Chen et al 2022).…”

“…Larvae also can migrate into host tissue, leading to tissue damage, inflammatory reactions, visual impairment, and blindness (Zhou et al 2020). T. canis can cause detrimental damage to the brain of intermediate or paratenic hosts (Chen et al 2022). Therefore, identifying different Toxocara is conducive to preventing and treating nematode infection in humans and animals.…”

The first report of co-infection with Sphaerirostris picae and Ascaridia galli in the Oriental magpie (Pica serica) in Beijing, China

“…The remaining DNA was stored at -20°C. PCR ampli cation of COX1 sequence in nematodes, COX1 gene ampli cation upstream primer (JB3): 5'-TTTTTTGGGCATCCTGAGTTTAT-3'; Downstream primers (JB4.5): 5'-TAAAGAAACAATGAAATG-3' [33], gene sequence about 441 bp. All PCR-positive products were puri ed and bidirectionally sequenced by BGI Gene Sequencing (Beijing, China).…”