title: The Cryptosporidium oocyst wall protein is a member of a multigene family and has a homolog in Toxoplasma.
abstract: Coccidian parasites are transmitted via a fecal oocyst stage that is exceptionally resistant to environmental stress and harsh chemical treatments, which allows parasites to stably persist outside a host. Because of its oocyst durability Cryptosporidium parvum is a significant water- and food-borne pathogen of humans, as well as animals of agricultural importance. To date, only one apicomplexan oocyst membrane protein has been identified, Cryptosporidium oocyst wall protein 1 (COWP1). COWP1 has a highly cysteine-rich periodicity due to arrays of two apicomplexan-specific motifs, designated the type I and type II domains. In this study, exhaustive BLAST screening of a complete C. parvum genome sequence database resulted in identification of eight additional genes encoding similar arrays of cysteine-rich type I and/or type II domains. Transcript expression analysis revealed that all COWP genes are abundantly expressed at a time when developing oocysts are observed, roughly 48 to 72 h after inoculation of in vitro cultures. A monoclonal antibody recognizing COWP8 specifically localized to the C. parvum oocyst wall, supporting the hypothesis that multiple COWPs play a role in the oocyst wall structure. BLAST screening of the Toxoplasma gondii genome sequence database resulted in identification of a gene encoding at least one COWP homolog (TgOWP1), and this multiexon sequence information was used to isolate a full-length cDNA. Exhaustive screening of Plasmodium sp. genome sequence databases by using COWP genes as BLAST queries failed to detect similar proteins in PLASMODIUM: We therefore propose that the COWP family of proteins have a structural role in apicomplexan species that produce durable shed cysts capable of surviving environmental stress.
authors.affiliation: Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York 10021, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Templeton
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Lancto
authors.forename: Vladimir
authors.initials: V
authors.lastname: Vigdorovich
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Nicole R
authors.initials: NR
authors.lastname: London
authors.forename: Kelly Z
authors.initials: KZ
authors.lastname: Hadsall
authors.forename: Mitchell S
authors.initials: MS
authors.lastname: Abrahamsen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016785:Cryptosporidium parvum / Q000737:chemistry*; D008969:Molecular Sequence Data; D005810:Multigene Family; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D016415:Sequence Alignment; D014122:Toxoplasma / Q000737:chemistry*
chemical_list: D015800:Protozoan Proteins; C106305:oocyst wall protein, Cryptosporidium