Whipworms of south-east Asian rodents are distinct from Trichuris muris

Abstract

The whipworm Trichuris muris is known to be associated with various rodent species in the northern hemisphere, but the species identity of whipworm infecting rodents in the Oriental region remains largely unknown. We collected Trichuris of Muridae rodents in mainland and insular Southeast Asia between 2008 and 2015 and used molecular and morphological approaches to identify the systematic position of new specimens. We discovered two new species that were clearly distinct from T. muris, both in terms of molecular phylogenetic clustering and morphological features, with one species found in Thailand and another one in Borneo. We named the new species from Thailand as Trichuris cossoni and the species from Borneo as Trichuris arrizabalagai. Molecular phylogeny using internal transcribed spacer region (ITS1-5.8S-ITS2) showed a divergence between T. arrizabalagai n. sp., T. cossoni n. sp. and T. muris. Our findings of phylogeographically distinct Trichuris species despite some globally distributed host species requires further research into the distribution of different species, previously assumed to belong to T. muris, which has particular relevance for using these species as laboratory model organisms.

Morphological and molecular characterization of Trichuris muris (Nematoda: Trichuridae): studies from two commensal rodent species

“…Trichuris muris was originally described by Schrank (1788) from an unspecified mouse species in Germany, but the host was most likely Mus musculus (Ribas et al , 2020). Later, Hall (1916) compiled data on T. muris from M. musculus , Rattus rattus and other wild rodents (e.g.…”

“…To date, few molecular studies have been carried out on Trichuris parasites of rodents and records mainly correspond to T. muris (e.g. Callejón et al , 2010; Wasimuddin et al , 2016; Ribas et al , 2020). There are reports of at least 21 genes of this Trichuris species in seven rodent host species from Europe and Asia (e.g.…”

Mitogenomics and Evolutionary History of Rodent Whipworms (Trichuris spp.) Originating from Three Biogeographic Regions

“…Whipworms are common parasites of rodents, often showing prevalence over 20% in wild populations (e.g., 21.1% in Mus musculus in Central Europe [9], 23 and 38.5% in Mastomys natalensis in Africa [10,11], or 22% in Sundamys muelleri from Southeast Asia [12]. The mouse whipworm, Trichuris muris, is extensively used as an animal model of T. trichiura, the human whipworm [13], and is one of the three fully sequenced whipworm genomes together with T. trichiura [14] and T. suis [15].…”

“…This is unfortunate, since whipworms are often difficult to distinguish by morphology alone, and genetic data are helpful to reveal cryptic diversity [10,23,24]. In fact, molecular methods have become an increasingly important tool for completing the morphological description of different whipworm species, e.g., T. arvicolae [24], T. mastomysi and T. carlieri [10], T. cutillasae [25], or, most recently, T. cossoni [12]. Genetic studies based on nuclear markers, such as ITS-1, ITS-2, or 5.8S, have proven useful to distinguish closely related whipworm species [1,25,26].…”

“…In this study, we characterised and performed a comparative genomic analysis of seven Trichuris mitochondrial genomes from different rodent species. Three of our samples are previously described whipworm species, Trichuris mastomysi [28], Trichuris arvicolae [24], and Trichuris cossoni [12]. Our whipworm samples cover three biogeographic regions (see Table 1): four species come from Afrotropical Muridae rodents, two species from Indomalayan Muridae rodents, and the remaining species from a Cricetidae rodent from the Palaearctic region.…”