|BLAZEJEWSKI, BLAZEJEWKSI - Hospital For Sick Children (SICKKIDS)|
|NURSIMULU, NIRVANA - Hospital For Sick Children (SICKKIDS)|
|PSZENNY, VIVIANA - National Institutes Of Health (NIH)|
|DANGOUDOUBIYAM, SRIVENY - University Of Kentucky|
|NAMASIVAYAM, SIVARANJANI - University Of Georgia|
|CHIASSON, MELISSA - National Institutes Of Health (NIH)|
|CHESSMAN, KYLE - Hospital For Sick Children (SICKKIDS)|
|TONKIN, MICHELLE - University Of Victoria|
|SESHADRI, SWAPNA - Hospital For Sick Children (SICKKIDS)|
|HUNG, STACY - University Of Victoria|
|BRIDGERS, JOSHUA - University Of Victoria|
|RICKLEFS, STACY - University Of Toronto|
|BOULANGER, MARTIN - University Of Victoria|
Submitted to: mBio
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2014
Publication Date: 2/10/2015
Citation: Blazejewski, B., Nursimulu, N., Pszenny, V., Dangoudoubiyam, S., Namasivayam, S., Chiasson, M., Chessman, K., Tonkin, M., Seshadri, S., Hung, S., Bridgers, J., Ricklefs, S., Boulanger, M., Dubey, J.P. 2015. Systems based analysis of the Sarcocystis neurona genome identifies pathways that contribute to a heteroxenous life cycle. mBio. 6(1):e02445-14.
Interpretive Summary: Sarcocystis neurona is a member of the coccidia, a clade of single celled apicomplexan parasites responsible for causing major economic and health burdens worldwide. A cousin of Plasmodium, Cryptosporidium, Theileria, and Eimeria, Sarcocystis is one of the most successful parasite genera; capable of infecting all vertebrates (fish, reptiles, birds and mammals – including humans). The past decade has witnessed an increasing number of human outbreaks of clinical significance associated with acute sarcocystosis. Among Sarcocystis species S. neurona has a wide host range and causes fatal encephalitis in horses, marine, and several other mammals. To provide insights into the transition from a purely enteric parasite (e.g. Eimeria) to one that forms tissue cysts (Toxoplasma), we present the first genome sequence of Sarcocystis neurona. Comparisons with other coccidian genomes highlights the molecular innovations that drive its distinct life cycle strategies. These findings will be of interest to biologists and Parasitologists.
Technical Abstract: Sarcocystis neurona is a member of the Coccidia, a clade of single-celled parasites of medical and veterinary importance including Eimeria, Sarcocystis, Neospora and Toxoplasma. Unlike Eimeria, a single host enteric pathogen, Sarcocystis, Neospora and Toxoplasma are two host parasites that infect and produce infectious tissue cysts in a wide range of intermediate hosts. As a genus, Sarcocystis is one of the most successful protozoan parasites; all vertebrates, including birds, reptiles, fish and mammals are hosts to at least one Sarcocysti species. Here we sequenced Sarcocystis neurona, the causal agent of fatal equine protozoal myeloencephalitis. The S. neurona genome is 127 Mbp, more than twice the size of other sequenced coccidian genomes. Comparative analyses identified conservation of the invasion machinery among the coccidia. However many dense granule and rhoptry kinase genes, responsible for altering host effector pathways inTox oplasma and Neospora, are absent from S. neurona. Further, S. neurona has a divergent repertoire of SRS proteins, previously implicated in tissue cyst formation in Toxoplasma. Systems based analyses identified a series of metabolic innovations, including the ability to exploit alternative sources of energy. Finally we present a S. neurona model detailing conserved molecular innovations that promote the transition from a purely enteric lifestyle (Eimeria) to a heteroxenous parasite capable of infecting a wide range of intermediate hosts.