Molecular identification of the rodent-borne pathogen Rodentolepis nana using the genetic markers of ITS-1, 18 S, and 28 S rDNA.

BACKGROUND: Rodentolepis nana (syn. Hymenolepis nana), the most common cyclophyllid tapeworm infecting rodents, is a well-studied gastrointestinal parasite in mice and belongs to the family Hymenolepididae. METHODS: The present study focuses on the molecular analysis for the nuclear genes (ITS-1, 18 S, and 28 S rDNA) used for the accurate recognition of the recovered Rodentolepis species. RESULTS: The annotated partial ITS-1, 18 S, and 28 S rDNA gene regions were deposited in GenBank (gbǀ MW310394.1, gbǀ MW327585.1, and gbǀ MW324479.1, respectively) and further used in the maximum likelihood method (ML) to clarify their genetic relationships at the species level. The interrogation sequence of R. nana was aligned and belonged to the family Hymenolepididae, in the same group as all Hymenolepis species, which were distinct from Cyclophyllidea cestodes, especially species belonging to Anoplocephalidae and Taeniidae. Sequence data support the paraphyly of Hymenolepis species. CONCLUSIONS: The phylogeny supports the availability of the ITS-1, 18 S, and 28 S rDNA genes as reliable genetic markers for evolutionary relationships.

Gene-based molecular characterization of cox1 and pnad5 in Hymenolepis nana isolated from naturally infected mice and rats in Saudi Arabia.

Mice and rats are animals commonly used in research and laboratory testing. Compared with other animal species, they harbor many more zoonotic agents. Hymenolepis nana (H. nana) is a common tapeworm that parasitizes both humans and rodents. Although this tapeworm is of socio-economic importance worldwide, information related to its mitochondrial genome is limited. The present study examined the sequence diversity of two mitochondrial (mt) genes, subunit I of cytochrome oxidase (cox1) and NADH dehydrogenase subunit 5 (pnad5), of H. nana in mice and rats from two geographical regions of Saudi Arabia (Makkah and Riyadh). Partial sequences of cox1 and pnad 5 from individual H. nana isolates were separately amplified using polymerase chain reaction (PCR) and sequenced. The GC contents of the sequences ranged between 31.6-33.5% and 27.2-28.6% for cox1 and pnad5, respectively. The genomic similarity among specimens determined via cox1 primer and pnad5 primer was 97.1% and 99.7%, respectively. Based on these primers, our data did not indicate any differences between H. nana from rat and mice isolates. Results demonstrated that the present species are deeply embedded in the genus Hymenolepis with close relationship to other Hymenolepis species, including H. nana as a putative sister taxon, and that the isolates cannot be categorized as belonging to two different groups with origins in Makkah and Riyadh.

Infectivity and development of the human strain of Hymenolepis nana in ICR mice.

In order to study the infectivity and development of the human strain of Hymenolepis nana in mice, a human strain of H. nana was inoculated into ICR mice. H. nana eggs were concentrated by the sedimentation method and inoculated by a disposable syringe (1 ml) connected to a long needle (8 cm) into the stomach of mice. Mouse feces were examined daily beginning day 5 after inoculation and the mice were sacrificed from days 19 to 65 post-infection (PI). The infection rate and worm recovery rate were 69% and 17%, respectively. The prepatent period ranged from 7 to 23 days. Autoinfection was found to occur in an ICR mouse infected with 60 eggs; 102 worms were recovered from its small intestinal lumen on day 19 PI. One row of hooklets was found on the scolex and the mean number of hooks was 19. The average length, width, and number of segments were 51 mm, 0.6 mm, and 1,099, respectively. The mean length and number of immature segments were 9 mm and 414 segments, mature segments 20 mm and 390 segments, and gravid segments 22 mm and 295 segments. The average length, width, and number of segments in 26 autoinfected worms were 11.5 mm, 0.3 mm, and 189 segments. The mean length and number of immature segments were 3.9 mm and 41 segments, mature segments 4.4 mm and 65 segments, and gravid segments 3.2 mm and 83 segments, respectively.