|CALER-BERNAL, RAFAEL - Non ARS Employee|
|VERMA, SHIV - Non ARS Employee|
Submitted to: Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2015
Publication Date: 8/25/2015
Citation: Dubey, J.P., Dunams, D.B., Caler-Bernal, R., Verma, S., Rosenthal, B.M. 2015. Molecular characterization and development of Sarcocystis speeri sarcocysts in gamma interferon gene knockout mice. Parasitology. 142:1555-1562.
Interpretive Summary: Coccidian parasites in the phylum Apicomplexa include myriad parasites that are transmitted when a definitive host consumes the infected tissue of an intermediate host, or when an intermediate host consumes water or food contaminated with the feces of a definitive host. Toxoplasma gondii is an important zoonotic parasite that compromises food safety by infecting tissues of food animals and by contaminating produce. This parasite is difficult to distinguish from many similar parasites that cause no known risk to human health. Among these are parasites in the genus Sarcocystis known to cause encephalitis in a variety of mammalian and avian hosts. Here, we provide the first morphological and molecular description of a parasite, Sarcocystis speeri, which completes its lifecycle in Virginia opossums. The results will be useful in the diagnosis of these enigmatic parasites, and help distinguish them from other parasites know (or suspected) to endanger human health. This paper should be of interest to biologists, parasitologists, and veterinarians.
Technical Abstract: The North American opossum (Didelphis virginiana) is the definitive host for at least three named species of Sarcocystis: S. falcatula, S. neurona, and S. speeri. It appears that there may be additional undescribed species of Sarcocystis in D. virginiana feces. The South American opossums (D. albiventris, D. marsupialis, and D. aurita) act as definitive host for S. falcatula and S. lindsayi. The sporocysts of these Sarcocystis species are similar morphologically. They are also not easily distinguished genetically because of the difficulties of DNA extraction from sporocysts and availability of distinguishing genetic markers. Some of these species can be distinguished by bioassay; S. neurona and S. speeri are infective to gamma interferon gene knockout (KO) mice but not to budgerigars (Melopsittacus undulatus) whereas S. falcatula and S. lindsayi are infective to budgerigars but not to KO mice. The natural intermediate host of S. speeri is unknown. In the present study, development of S. speeri in the KO mice is described. Preliminary results on DNA characterized from S. speeri cellculture derived merozoites revealed that the parasite is closely related to S. neurona. These results should be useful in finding natural intermediate host of S. speeri.