Prevalence and phylogeography of Taenia hydatigena metacestodes from goats of India

Abstract

The study determined the prevalence and genetic population structure relationships of Cysticercus tenuicollis (Taenia hydatigena metacestode) retrieved from the goats slaughtered in north India. An overall prevalence of 9.62% (59/613) was recorded. Genetic population structure relationships were assessed by targeting partial cytochrome c oxidase subunit 1 mitochondrial gene sequence. Phylogenetic tree analysis revealed that all the present study representative isolates (n = 7) formed a major clade and grouped with T. hydatigena isolates retrieved from sheep, goats, pigs and dogs, originating from China, Iran, Nigeria, Ghana and Poland. However, a single isolate from Himachal Pradesh (isolate 3) formed a subgroup within the clade. The neutrality and diversity indices revealed high values of haplotype diversity [Hd = 0.99695 (0.95238–1.0000)] and low nucleotide diversity (π = 0.49276), which was indicative of demographic expansion and low gene flow, suggesting that Indian T. hydatigena isolates were not genetically differentiated. Tajima's D (−1.26988) and Fu and Li's D statistics values (−0.74556) were negative, demonstrating deviations from neutrality and both propounded recent population expansion or purifying selection. Results highlighted a low genetic diversity of T. hydatigena metacestodes across the geographical range of north India.

Keywords: Cysticercus tenuicollis; cytochrome c oxidase subunit 1 gene; genetic variation; phylogeography.

Graphical abstract

Fig. 1.

Cysticercus tenuicollis (Taenia hydatigena metacestode) retrieved from slaughtered goats.

Fig. 2.

PCR amplification targeting the mitochondrial cox1 gene. M: 100 bp plus marker; P: positive (Taenia hydatigena) control; N: negative template (Echinococcus granulosus) control; 1–4: PCR products.

Fig. 3.

Phylogenetic tree of Cysticercus tenuicollis (Taenia hydatigena metacestode) isolates retrieved from goats in relation to different GenBank archived isolates of intermediate and definitive hosts based on mitochondrial cox1 gene. The phylogenetic tree was constructed by the maximum-likelihood method using MEGA X software. The evolutionary distances were computed using the maximum composite likelihood method and are in the units of the number of base substitutions per site. Moniezia expansa (AB099693.1) was used as out-group species to root the tree.

Fig. 4.

Median-joining network of Cysticercus tenuicollis isolates from different hosts and geographical regions using partial mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Circle size is relative to haplotype frequency. Bars/hatch marks indicate the number of haplotype substitutions/mutations.

Fig. 5.

Median-joining network of north Indian Cysticercus tenuicollis isolates retrieved from goats using partial mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Circle size is relative to haplotype frequency. Bars/hatch marks indicate the number of haplotype substitutions/mutations.