Morphological and molecular phylogenetic characterization of Sarcocystis kani sp. nov. and other novel, closely related Sarcocystis spp. infecting small mammals and colubrid snakes in Asia

Morphological and Molecular Identification of Sarcocystis arctica in Captive Cheetahs (Acinonyx jubatus) in China Helps Clarify Phylogenetic Relationships with Sarcocystis caninum and Sarcocystis felis

To date, only one case is known where protozoan parasites of the genus Sarcocystis were found to infect cheetahs (Acinonyx jubatus); the cysts in the musculature were morphologically identified as S. felis. Here, we characterized sarcocysts by morphological and molecular methods that were observed in cheetahs who died in zoos in China. Only one type of sarcocyst was present in two of six cheetahs. By light microscopy, the sarcocyst wall was striated, 1.4-2.1 μm thick. Ultrastructurally, the wall had irregular-shaped, small villar protrusions, resembling wall type 9c, similar to those of S. arctica, S. caninum, and S. felis. The samples shared their highest molecular identity values with those of S. arctica and S. caninum: 99.9-100% and 99.8-100% (18S rRNA), 99.5% and 99.3-99.5% (28S rRNA), 95.9-97.5% and 96.3-97.3% (ITS-1), and 99.6% and 99.2-99.7% (cox1), respectively. Compared with ITS-1 of S. felis, identities ranged between 87.5% and 88.9%. Phylogenetic reconstruction revealed that the newly sequenced Sarcocystis clustered with S. arctica and S. caninum, whereas S. felis (ITS-1) and S. canis (ITS-1, 18S rRNA, cox1) were sister species. Thus, we addressed the Sarcocystis species from the cheetahs as S. arctica, which is the first record of a Sarcocystis species believed to be specific for canids as intermediate hosts to infect a feline host.

Sarcocystis Cymruensis in the Brown Rat (Rattus Norvegicus) from an Urban District in Kuwait: Detailed Morphologic and Molecular Characterization

PURPOSE

The objective of the study was to establish the prevalence of Sarcocystis (Apicomplexa, Sarcocystidae) in brown rats from Jleeb Al-Shuyoukh, Kuwait, and to describe detected parasites using morphological and DNA analysis methods.

METHODS

Ninety-eight brown rats (Rattus norvegicus) were examined for Sarcocystis spp. Obtained sarcocysts were investigated using light microscopy and electron microscopy. The detected Sarcocystis species was characterised at nuclear 18S and 28S ribosomal RNA (rRNA), internal transcribed spacers 1 and 2, (ITS1 and ITS2), mitochondrial cytochrome c oxidase subunit I (cox1) and cytochrome b (cytb), and apicoplast RNA polymerase beta subunit (rpoB).

RESULTS

Sarcocysts were found in thigh muscles of 13.3% of the animals examined, while no oocysts/sporocysts were detected in faecal samples. Under a light microscope, sarcocysts were spindle-shaped, 850-3152 × 73-125 μm (1781 ± 763 × 99 ± 15 μm) in size and had thin (up to 0.9 μm) and apparently smooth cyst wall. By transmission electron microscopy, sarcocyst wall was 0.7-1.1 μm in thickness with numerous osmiophilic bleb-like protrusions. Based on DNA sequencing the sarcocysts examined were identified as S. cymruensis. Notably, ITS2 and rpoB sequences of S. cymruensis were obtained for the first time. No intraspecific variation was detected comparing 28S rRNA, ITS1, cox1 and cytb sequences of S. cymruensis isolated from Kuwait, Grenada and China. According to phylogenetic analysis, S. cymruensis was most closely related to S. muris, S. myodes and S. ratti using rodents as their intermediate hosts and cats as their identified or predatory mammals as their presumed definitive hosts.

CONCLUSION

We present the first report of S. cymruensis in Kuwait and in Persian Gulf area. The study shed light on the usefulness of different genetic loci for the characterization of Sarcocystis spp. from rodents.

Red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) as potential spreaders of Sarcocystis species

Background

Sarcocystis includes a global group of apicomplexan parasites with two-host life cycle frequently circulating in wildlife and domestic hosts, including humans. Two of the most important wild terrestrial carnivores acting as definitive hosts are the red fox and raccoon dog, due to their wide distribution in Europe and usage of wild and farmed animals as prey. This study was conducted to determine the prevalence of Sarcocystis in hunted red foxes and raccoon dogs from nine regions of the Czech Republic and to identify isolated sporocysts by molecular techniques.

Methods

Approximately 5 g of the contents of large intestine from 200 animals (197 red foxes and three raccoon dogs) were examined by flotation centrifugation coprological method. Only samples of 50 red foxes and one raccoon dog positive to Sarcocystis spp. were used for the nested PCR (nPCR) method to amplify a fragment or partial sequence on the cox1 gene. Ten species-specific primer pairs for detection of Sarcocystis spp. using farm animals as intermediate hosts were utilized.

Results

In total, 38.1% of the red foxes and 66.7% of the raccoon dogs were positive to Sarcocystis by light microscopy. The molecular characterization resulted in the identification of five species in the red fox: S. arieticanis, S. capracanis, S. cruzi, S. miescheriana, and S. tenella, while the PCR was negative for the sole raccoon dog. The highest intraspecific variation was found for S. miescheriana, while S. tenella was the most prevalent. Co-infections occurred in the large intestine of the red fox. No zoonotic species were found in our samples.

Conclusion

This is the first study where the potential role of the red fox and raccoon dogs as spreaders of Sarcocystis to farm animals in the Czech Republic is shown. The use of species-specific primers provides a fast and easy method for screening multiple samples for a particular Sarcocystis species.

First Observations of Buzzards (Buteo) as Definitive Hosts of Sarcocystis Parasites Forming Cysts in the Brain Tissues of Rodents in Lithuania

Representatives of the genus Sarcocystis are worldwide distributed apicomplexan parasites characterised by two-host prey-predator relationships. Sarcocystis spp. produce sarcocysts in the muscles and brains of intermediate hosts and develop sporocysts in the intestines of definitive hosts. Two species, Sarcocystis glareoli and Sarcocystis microti, previously assigned to the genus Frenkelia, form cysts in the brains of rodents and are transmitted through the common buzzard (Buteo buteo). In our study, brain samples of 694 small mammals caught in different regions of Lithuania were examined for Sarcocystis spp. Additionally, 10 B. buteo and two rough-legged buzzards (Buteo lagopus) were tested for sporocysts of the analysed parasites. Sarcocystis species were identified based on 28S rRNA sequence comparison. Of the eleven species of small mammals tested, Sarcocystis parasites were observed only in the bank vole (Clethrionomys glareolus). Cysts of S. glareoli were detected in 34 out of 374 C. glareolus (9.1%, 95% CI = 6.4-12.5%). Molecular investigation showed the presence of only S. glareoli in the intestines of 50% of B. buteo. Furthermore, two species, Sarcocystis sp. Rod3 and Sarcocystis sp. Rod4, were confirmed in B. lagopus. Our results demonstrate the need for further studies on Sarcocystis cycling between rodents and birds.

A cyst-forming coccidian with large geographical range infecting forest and commensal rodents: Sarcocystis muricoelognathis sp. nov

BACKGROUND

The geographic distribution and host-parasite interaction networks of Sarcocystis spp. in small mammals in eastern Asia remain incompletely known.

METHODS

Experimental infections, morphological and molecular characterizations were used for discrimination of a new Sarcocystis species isolated from colubrid snakes and small mammals collected in Thailand, Borneo and China.

RESULTS

We identified a new species, Sarcocystis muricoelognathis sp. nov., that features a relatively wide geographic distribution and infects both commensal and forest-inhabiting intermediate hosts. Sarcocystis sporocysts collected from rat snakes (Coelognathus radiatus, C. flavolineatus) in Thailand induced development of sarcocysts in experimental SD rats showing a type 10a cyst wall ultrastructure that was identical with those found in Rattus norvegicus from China and the forest rat Maxomys whiteheadi in Borneo. Its cystozoites had equal sizes in all intermediate hosts and locations, while sporocysts and cystozoites were distinct from other Sarcocystis species. Partial 28S rRNA sequences of S. muricoelognathis from M. whiteheadi were largely identical to those from R. norvegicus in China but distinct from newly sequenced Sarcocystis zuoi. The phylogeny of the nuclear 18S rRNA gene placed S. muricoelognathis within the so-called S. zuoi complex, including Sarcocystis attenuati, S. kani, S. scandentiborneensis and S. zuoi, while the latter clustered with the new species. However, the phylogeny of the ITS1-region confirmed the distinction between S. muricoelognathis and S. zuoi. Moreover, all three gene trees suggested that an isolate previously addressed as S. zuoi from Thailand (KU341120) is conspecific with S. muricoelognathis. Partial mitochondrial cox1 sequences of S. muricoelognathis were almost identical with those from other members of the group suggesting a shared, recent ancestry. Additionally, we isolated two partial 28S rRNA Sarcocystis sequences from Low's squirrel Sundasciurus lowii that clustered with those of S. scandentiborneensis from treeshews.

CONCLUSIONS

Our results provide strong evidence of broad geographic distributions of rodent-associated Sarcocystis and host shifts between commensal and forest small mammal species, even if the known host associations remain likely only snapshots of the true associations.