Sarcocystis stenodactylicolubris n. sp., a new sarcosporidian coccidium with a snake-gecko heteroxenous life cycle

Sarcocystis sp. shed by the common boa snake (Boa constrictor) in Brazil

The genus Sarcocystis contains around 200 species and 25 of these infect snakes. Two Sarcocystis spp. shed by snakes have called special attention of the scientific community. S. nesbitti, which is shed by scrub pythons (Simalia amethistina), causes myopathy in humans that consume water or food contaminated with the parasite. Sporocysts of S. singaporensis, excreted by reticulated pythons (Malayopython reticulatus), is letal for rats and was successfully tested in the biological control of these rodents. A high biodiversity of snakes is found in Brazil, however, scarce information is available about Sarcocystis spp. in Brazilian snakes. Herein, we investigated Sarcocystis sp. in feces of the common boa (Boa constrictor) from Salvador, as it is widely distributed in Brazil and it is also bred in other countries. Feces of 65 boas were examined, and Sarcocystis sp. was found in 1/65 (1.53%) snakes. All snakes were alive, and for this reason, intestinal scrapping, which is the most sensitive method to detect the parasite, was not performed. Morphometric evaluation of sporocysts showed significant differences in their sizes. PCR and multilocus sequencing of four genetic markers (cox1, 18S, ITS1, and 28S) revealed that sporocysts corresponded to a new Sarcocystis species. Sequences of cox1 and 18S had identities of 100% and higher than 98%, respectively, with sequences obtained from the rodent Lagostomus maximus in Argentina. ITS1 and 28S sequences did not match with any known Sarcocystis sp. No ITS1 and 28S sequences were available for the Sarcocystis sp. found in the Argentinian L.maximus. Bioassay using the boa sporocysts was conducted in three mouse lineages and in Rattus norvegicus, but no parasitic stages were detected in these rodents. We concluded that the common boa is probably the definitive host of a new species of Sarcocystis sp. that has L. maximus or related rodents as intermediate hosts.

Sarcocystis sp. infection (Apicomplexa: Sarcocystidae) in invasive California kingsnake Lampropeltis californiae (Serpentes: Colubridae) in Gran Canaria

Invasive species pose a threat not only to biodiversity because they displace or compete with native fauna, but also because of the pathogens they can host. The Canary Islands are an Atlantic biodiversity hotspot threatened by increasing numbers of invasive species, including the California kingsnake Lampropeltis californiae, which was recently introduced to Gran Canaria. Seventy-seven snakes were examined for gastrointestinal parasites in 2019–2020. Sporocysts of Sarcocystis sp. were detected in 10 of them; detection of gamogonia stages in histological sections of 3 snakes confirmed the snake as a definitive host. Partial ssrDNA was amplified using SarcoFext/SarcoRext primers; an additional sequence of Sarcocystis was obtained from the tail muscle of the endemic Gran Canaria giant lizard Gallotia stehlini for a comparison. Identical ssrDNA sequences of unknown Sarcocystis sp. were obtained from 5 different snakes. Phylogenetic analysis showed that Sarcocystis sp. isolated from invasive California kingsnakes is unrelated to Sarcocystis provisionally considered S. stehlini from the endemic lizard. The dixenous coccidia are rarely reported to invade new predator–prey systems. However, the present data suggest that previously unknown Sarcocystis sp. is circulating among invasive snakes and as yet unknown vertebrate intermediate hosts, with undetermined consequences for the Gran Canaria ecosystem.

Sarcocystis camelicanis increases interleukin (IL)-6 expression in one-humped camels (Camelus dromedarius) from Riyadh and Al Qassim, Saudi Arabia

Sarcocystis spp. are intracellular protozoan parasites with an intermediate-definitive host life cycle based on a prey-predator relationship. Sarcocystis infection is common among different vertebrates including humans. The pathogenicity of Sarcocystis spp. is of varied significance including a possible lethal effect for the host. The goal of the present study was to investigate the inflammatory activity of Sarcocystis spp. in different organs of naturally infected camels. The tongue, esophagus, heart, diaphragm, and skeletal muscles were collected from 50 camels, and the tissues assessed for the presence of Sarcocystis spp. by macroscopic examination, light microscopy, and transmission electron microscopy (TEM). Moreover, expression of the interleukin (IL)-6 was analyzed using reverse transcriptase quantitative polymerase chain reaction (qPCR). Microscopic Sarcocystis spp. cysts were found in camels. TEM identified the cysts as Sarcocystis camelicanis (S. camelicanis). Sarcocystis infection increased inflammation by stimulation of IL-6 expression in different organs of the camels, particularly in those from the Al-Qassim region.

Description of Sarcocystis scandentiborneensis sp. nov. from treeshrews (Tupaia minor, T. tana) in northern Borneo with annotations on the utility of COI and 18S rDNA sequences for species delineation

Sarcocystis scandentiborneensis sp. nov. was discovered in histological sections of striated musculature of treeshrews (Tupaia minor, T. tana) from Northern Borneo. Sarcocysts were cigar-shaped, 102 μm–545 μm long, and on average 53 μm in diameter. The striated cyst wall varied in thickness (2–10 μm), depending on whether the finger-like, villous protrusions (VP) were bent. Ultrastructurally, sarcocysts were similar to wall type 12 but basal microtubules extended into VPs that tapered off with a unique U-shaped, electron-dense apical structure. In phylogenetic trees of the nuclear 18S rRNA gene, S. scandentiborneensis formed a distinct branch within a monophyletic subclade of Sarcocystis spp. with (colubrid) snake-rodent life cycle. We mapped all intraspecific (two haplotypes) and interspecific nucleotide substitutions to the secondary structure of the 18S rRNA gene: in both cases, the highest variability occurred within helices V2 and V4 but intraspecific variability mostly related to transitions, while transition/transversion ratios between S. scandentiborneensis, S. zuoi, and S. clethrionomyelaphis were skewed towards transversions. Lack of relevant sequences restricted phylogenetic analysis of the mitochondrial Cytochrome C oxidase subunit I (COI) gene to include only one species of Sarcocystis recovered from a snake host (S. pantherophisi) with which the new species formed a sister relationship. We confirm the presence of the functionally important elements of the COI barcode amino acid sequence of S. scandentiborneensis, whereby the frequency of functionally important amino acids (Alanine, Serine) was markedly different to other taxa of the Sarcocystidae. We regard S. scandentiborneensis a new species, highlighting that structurally or functionally important aspects of the 18S rRNA and COI could expand their utility for delineation of species. We also address the question why treeshrews, believed to be close to primates, carry a parasite that is genetically close to a Sarcocystis lineage preferably developing in the Rodentia as intermediate hosts.

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Sarcocystis scandentiborneensis sp. nov. identified from Tupaia tana and T. minor.

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Putative snake-treeshrew life cycle.

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Unique brush-like cyst wall with an electron-dense apical structure.

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Transition/transversion ratios of 18S rDNA improve species discrimination.

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COI: Interspecific differences of functionally important amino acids of barcode area.

First molecular characterization and morphological aspects of Sarcocystis fusiformis infecting water buffalo Bubalus bubalis in Egypt

Fresh muscle samples from water buffalo (Bubalus bubalis) aged 2-15, from Giza Province, Egypt; were examined for Sarcocystis infection. Macroscopic ovoid sarcocysts embedded in the muscle tissues of the examined buffaloes were detected; they measured 152-230 (210 ± 7) μm in length and 37-119 (95 ± 3) μm in width. The esophagus was the most infected organ followed by the diaphragm, and tongue, while the heart muscles were the least infected. The cyst cavity was compartmentalized by septa derived from the ground substance located under the primary cyst wall. Using transmission electron microscopy, the primary cyst wall bordered sarcocysts were determined to be 0.08-0.22 μm in thickness, raised from the parasitophorous vacuolar membrane, and surrounded by a secondary cyst wall of host origin. The primary cyst wall had irregular wall folds with numerous cauliflower-like projections of variable sizes and shapes accompanied by knob-like electron-dense elevations. 18S rRNA gene expression studies confirmed that the present parasite isolates belonged to the genus Sarcocystis. The sequence data showed significant identities (>90%) with archived gene sequences from many Eimeriidae organisms, and a dendogram showing the phylogenetic relationship was constructed. The most closely related species was Sarcocystis fusiformis KR186117, with an identity percentage of 98%. The recovered sequences were deposited in the GenBank under the accession number MG572125. The present study, to our knowledge, is the first collective ultrastructural and molecular study that confirmed the taxonomy of sarcocysts isolated from water buffaloes in Egypt as Sarcocystis fusiformis.

A new Sarcocystis species (Apicomplexa: Sarcocystidae) from the rock gecko Bunopus tuberculatus in Saudi Arabia

Sarcocystis bunopusi n. sp. from the muscle fibres of the rock gecko ( Bunopus tuberculatus ) in Saudi Arabia is described. Sarcocysts were found in skeletal muscles of the tail and fore and hind limbs in 3 of 30 geckos. Sarcocysts were microscopic, 42-45 µm long and 22-25 µm wide. Using light microscopy, the cyst wall was thin and smooth. Ultrastructurally, the primary cyst wall consisted of a thin parasitophorous vacuolar membrane with osmiophilic 100 nm × 50 nm knob-like papillae, and no perpendicular protrusions. Septae were indistinct. Bradyzoites were 5-7 × 1.5-2.0 µm in size. This is the first description of a Sarcocystis species from this gecko.

Sarcocystis acanthocolubri sp. n. infecting three lizard species of the genus Acanthodactylus and the problem of host specificity. Light and electron microscopic study

In the present investigation, macroscopic sarcocysts of Sarcocystis acanthocolubri were observed in muscles of 42 (4.3%) out of 975 Acanthodactylus sp. lizards collected from different geographical areas in Egypt. The infection rate was 6.4% in Acanthodactylus boskianus, 2.1% in Acanthodactylus sculentus, and 5% in Acanthodactylus paradalis. The highest infection rate was recorded in the lizards captured from Baltem (10% in A. boskianus and 8% in A. paradalis). The infection rate was usually higher in females (7.4%) than in males (3.8%). Moreover, the highest infection rate was recorded in summer (7.53%), autumn (3.57%), and spring (3.11%), and the lowest was recorded in winter (0.91%). Also, old animals had higher infection rates (10.8%) than young ones (0-2.7%). Macrocysts measured 0.95 × 10.12 mm. Both macroscopic and microscopic sarcocysts were enclosed only by a primary cyst wall, which had many finger-like, stalkless, and non-branched protrusions giving it a striated appearance. The primary cyst wall measured 3.9 μm. A dark granulated ground substance was found directly underneath the protrusions and is extended interiorly dividing the cyst cavity into many compartments containing the parasites (metrocytes and merozoites). Metrocytes were found directly under the ground substance and usually multiply asexually by endodyogeny producing two merozoites from each metrocyte. Both metrocytes and merozoites had the apical complex structures characteristic to the genus Sarcocystis. Transmission experiments with three snake species indicated that the snake Spalerosophis diadema is the proper final host belonging to the family Colubridae. The prepatent period was 16 days, while the patent period was 35 days. The results obtained from the present investigation revealed that this is a new species which was named Sarcocystis acanthocolubri.

Life cycle of Sarcocystis camelicanis infecting the camel (Camelus dromedarius) and the dog (Canis familiaris), light and electron microscopic study

In the present study, the heteroxeneous life cycle of Sarcocystis sp. infecting camels were studied. A total of 180 slaughtered camels collected from different localities in Egypt were investigated for sarcocysts. Only 116 animals were found to be infected (the infection rate was 64%). Muscle samples of esophagus, diaphragm, tongue, skeletal, and heart muscles were examined. Exclusively, microscopic sarcocysts were detected in all examined organs. The infection rates of the esophagus, diaphragm, tongue, skeletal, and heart muscles were 60%, 50%, 40%, 40%, and 10%, respectively. By means of transmission electron microscopy, details of the ultrastructure of the sarcocysts were studied. The specific architecture and ornaments of the cyst wall, its protrusions, and the cyst interior were recorded. Unique features of protrusions of the primary cyst wall, the knob-like structures, arise around each protrusion. Experimental infection of carnivores by feeding heavily infected camel muscles revealed that the dog, Canis familiaris, is the only final host of the present Sarcocystis species. Gamogony, sporogonic stages, and characteristics of sporulated oocysts were also investigated.