The apicomplexan parasite, Sarcocystis neurona causes the degenerative neurological equine protozoal myeloencephalitis (EPM) disease of horses. Due to its host range expansion, S. neurona is an emerging threat that requires close monitoring. In apicomplexans, protein kinases (PKs) have been implicated in a myriad of critical functions such as host cell invasion, cell cycle progression and host immune responses evasion. Here, we used various bioinformatics methods to define the kinome of S. neurona and phylogenetic relatedness of its PKs to other apicomplexans. Further, three-dimensional (3D) homology models for selected S. neurona putative PKs were constructed and evaluated for inhibitor docking. We identified 92 putative PKs clustering within the AGC, CAMK, CK1, CMGC, STE, TKL, aPK and OPK groups. Although containing the universally conserved PKA (AGC group), S. neurona kinome was devoid of PKB and PKC, but contained the six apicomplexan conserved CDPKs (CAMK group). The OPK group was represented by ROPKs 19A, 27, 30, 33, 35 and 37, but was devoid of the virulence-associated ROPKs 5, 6, 18 and 38. Two out of the three S. neurona CK1 enzymes had high sequence similarities to T. gondii TgCK1-α and TgCK1-β and the Plasmodium PfCK1. Docking of four inhibitors onto homology models of putative ROP27 and PKA indicated that inhibition of S. neurona PKs is feasible, but needs to be experimentally tested. The essentiality of apicomplexan PKs makes the elucidation of S. neurona kinome a key milestone for development of novel therapeutics for EPM.

Chamois are mountain ungulates (Subfamily Caprinae) which inhabit several medium and high altitude mountain ranges from southern Europe to the Near East. The first findings of Sarcocystis cysts in the musculature of chamois were reported in the 1970s. However, only limited work on the epidemiology of sarcocystosis and identification of the species of Sarcocystis in chamois has been done in the past. The present work was part of a comprehensive study on the parasites of chamois in Germany aiming to provide, for the first time, data on the prevalence and intensity of Sarcocystis infection in native Alpine chamois using histology examination of heart and/or diaphragm tissue samples collected from 216 chamois (40 kids and 176 chamois ranging of one up to 18 years of age). Sarcocysts were detected in either heart or diaphragm of 167/216 chamois (77.3%) with 131 of 183 heart samples and 127 of 215 diaphragm samples testing sarcocyst positive. Of the 181 chamois with both heart and diaphragm available (34 kids and animals up to 18 years of age), sarcocysts were detected in heart and/or diaphragm of 142 animals translating in an overall 78.5% prevalence of Sarcocystis infection (95%CI 72.5% - 84.4%). Sarcocysts were more frequently recorded in heart vs. diaphragm (72.4% vs. 56.4%; p=0.0021), and diaphragm positivity was associated with heart positivity (p=0.0001). Sarcocyst positivity (heart and/or diaphragm) was significantly (p<0.001) lower in kids than in the older chamois (27.1% vs. 88.6%, respectively) but prevalence did not differ between the sexes, regardless of the chamois’ age (p>0.3). Intensity of infection was generally low (<10 sarcocysts per cm² muscle cut) in both heart positive and diaphragm positive animals (94.7% and 93.7%, respectively) with heart yielding higher sarcocyst counts than diaphragm (p<0.001). Both heart and diaphragm sarcocyst counts were significantly (p<0.001) lower in kids than in the older chamois. Sarcocystis infection was demonstrated to be prevalent in chamois in Germany but intensity is apparently low. Further studies are desired to identify the species of Sarcocystis parasitizing the chamois using both phenotypic and molecular characteristics.

Sarcocystis sp. are coccidian protozoans belonging to the Apicomplexa phylum. As other members of this phylum, they are obligate intracellular parasites having a complex cellular machinery for the invasion of host cells. Sarcocystis spp. display dixenous life cycles, involving a predator and a prey as definitive and intermediate hosts, respectively. Specifically, these parasites develop sarcocysts in the tissues of their intermediate hosts, ranging in size from microscopic to visible to the naked eye, depending on the species. When definitive hosts consume sarcocysts, infective forms are produced in the digestive system and discharged into the environment via feces. Consumption of oocyst-contaminated water and pasture by the intermediate host completes the parasitic cycle. More than 200 Sarcocystis spp. have been described infecting wildlife, domestic animals, and humans, some of which are of economic or public health importance. Interestingly, Old World camelids (dromedary, domestic Bactrian camel, and wild Bactrian camel) and New World or South American camelids (llama, alpaca, guanaco, and vicuña) can each be infected by two different Sarcocystis species: Old World camelids by S. cameli (producing micro- and macroscopic cysts) and S. ippeni (microscopic cysts); and South American camelids by S. aucheniae (macroscopic cysts) and S. masoni (microscopic cysts). Large numbers of Old and New World camelids are bred for meat production, but the finding of macroscopic sarcocysts in carcasses significantly hampers meat commercialization. This review tries to compile the information that is currently accessible regarding the biology, epidemiology, phylogeny, and diagnosis of Sarcocystis spp. infecting Old and New World camelids. In addition, knowledge gaps will be identified to encourage research that will lead to the control of these parasites.

Sracocystis cruzi in cattle (Bos taurus) and Sarcocystis poephagicanis in yaks (Bos grunniens) are morphologically indistinguishable. However, the relationship of the two parasites is still un-clear. Here, muscular tissues of the two domestic animals collected from abattoirs in China were examined for sarcocysts of S. cruzi and S. poephagicanis. The sarcocysts isolated from the samples were processed for light microscopy (LM), transmission electron microscopy (TEM), and DNA analysis. Sarcocysts of S. cruzi and S. poephagicanis were found in 405 of 950 (42.6%) cattle and 304 of 320 (95.0%) yaks, respectively. By LM and TEM, the sarcocysts of the two parasites showed similar morphologically characteristics. The thin-walled sarcocysts had hair-like protrusions on the surface. Ultrastructures exhibited the primary cyst wall contained irregularly folded, hirsute or bone-like protrusions. Four genetic markers, 18S rDNA, 28S rDNA, mitochondrial cox1, and apicoplast rpl6 of the two parasites were sequenced and analyzed. The sequences of the four loci presented an interspecific identity of 97.9−98.6%, 97.2−98.1%, 89.5−90.4%, and 96.9−97.2%, respec-tively. Phylogenetic analysis using 28S rDNA and cox1 sequences indicated that both species were placed into a group encompassing Sarcocystis spp. in ruminants with canid as known or putative definitive hosts. Sarcocystis cruzi and S. poephagicanis should represent separated species, and cox1 and rpl6 was suitable for distinguishing between them.