Hiding in plain sight: discovery and phylogeography of a cryptic species of Trichinella (Nematoda: Trichinellidae) in wolverine (Gulo gulo).

Understanding parasite diversity and distribution is essential in managing the potential impact of parasitic diseases in animals and people. Imperfect diagnostic methods, however, may conceal cryptic species. Here, we report the discovery and phylogeography of a previously unrecognized species of Trichinella in wolverine (Gulo gulo) from northwestern Canada that was indistinguishable from T. nativa using the standard multiplex PCR assay based on the expansion segment 5 (ESV) of ribosomal DNA. The novel genotype, designated as T13, was discovered when sequencing the mitochondrial genome. Phylogenetic analyses of the mitochondrial genome and of 15 concatenated single copy orthologs of nuclear DNA indicated a common ancestor for the encapsulated clade is shared by a subclade containing Trichinella spiralis and Trichinella nelsoni, and a subclade containing T13 and remaining taxa: T12 + (T2 + T6) + [(T5 + T9) + (T3 + T8)]. Of 95 individual hosts from 12 species of mammalian carnivores from northwestern Canada from which larvae were identified as T. nativa on multiplex PCR, only wolverines were infected with T13 (14 of 42 individuals). These infections were single or mixed with T. nativa and/or T6. Visual examination and motility testing confirmed that T13 is encapsulated and likely freeze-tolerant. We developed a new Polymerase Chain Reaction-Restriction Fragment Length Polymorphism which unequivocally distinguishes between T13 and T. nativa. We propose Trichinella chanchalensis n. sp. for T13, based on significant genetic divergence from other species of Trichinella and broad-based sampling of the Trichinella genome. Exploration of Alaskan and Siberian isolates may contribute to further resolution of a phylogeographically complex history for species of Trichinella across Beringia, including Trichinella chanchalensis n. sp. (T13).

[Morpholgical, histological and histochemical observations on the effect of albendazole on encysted larvae of Trichinella spiralis in mice].

AIM: To study the mechanism of action of albendazole on encysted larvae of Trichinella spiralis in mice. METHODS: Twelve Kunming strain mice each infected with 200 T. spiralis larvae were equally divided into two groups. Six mice of the treatment group were treated with 30 mg of albendazole/kg daily for 5 days. Morphological, histological and histochemical methods were used. RESULTS: The encysted larvae of albendazole-treated group became significantly damaged, most worms were shrunken and surrounded by inflammatory cells. Histochemical study demonstrated that the glycogen and RNA content of the larvae in the treated group was decreased, the activities of SDH, ATPase, ACP were lower than those of the control group. CONCLUSION: Albendazole can affect the physiological function of Trichinella spiralis.

Histochemical and morphological studies on Trichinella spiralis larvae treated with high hydrostatic pressure.

Histochemical and morphological observations were made on Trichinella spiralis larvae treated with hydrostatic pressures of 100, 150, 200 and 300 MPa using hematoxylin-eosin (HE), periodic acid-Schiff (PAS) and Azan staining. Few histochemical changes were observed in HE and PAS stained larvae after pressurization at 200 MPa and under. However, red staining by Azan changed to blue in the anterior stichosome of larvae and skeletal muscle of mice, when the hydrostatic pressure was raised from 150 to 300 MPa. At 150 and 200 MPa, boundaries among stichocytes were indistinct or irregular, and unstained areas were observed in stichocytes of larvae using Azan staining. At 300 MPa, all tissues of larvae and mouse muscle stained blue with Azan. At the same pressure, decrease in PAS positive staining of stichocytes and dilation of muscular cells were observed in larvae. It is assumed that these histochemical and morphological changes in pressurized larvae might be related to the loss of infectivity of larvae.

Immunocytochemical localization of antigens in adult worms of Trichinella spiralis recognized by Fischer rats.

We demonstrate the tissue localization, in adult Trichinella spiralis, of antigens recognized by Fischer rat sera at 32 weeks postinfection. Immunodominant antigens were located in a wide variety of tissues, including type 1 stichocyte granules, stichocyte cytoplasm, the canalicular tree, hemolymph, hypodermis, hypodermal glands, cord cytoplasm, intestinal-gland cell granules, membranous structures in the midgut epithelium, midgut-occupying substance, brush border, hindgut epithelial cytoplasm, hindgut cuticle, vaginal cuticle, epithelial cytoplasm of the female genital tract, microvilli and discrete areas of the ovum, embryo sheath, intersperm space, discrete areas in immature sperm, small granules and cup-shaped membrane structures of sperm, and exocrine granules in the seminal vesicle and ejaculatory duct. A small amount of antigen was located in the inner layers of the genital portion of the body cuticle. The precise localization of antigens in adult worms should form a basis for better analysis of T. spiralis-related immunology.