Cryptosporidium parvum
From DrugPedia: A Wikipedia for Drug discovery
Cryptosporidium parvum
It is one of several species that cause cryptosporidiosis, a parasitic disease of the mammalian intestinal tract.
| Kingdom | Chromalveolata |
|---|---|
| Phylum | Apicomplexa |
| Class | Conoidasida |
| Subclass | Coccidiasina |
| Order | Eucoccidiorida |
| Family | Cryptosporidiidae |
| Genus | Cryptosporidium |
| Species | C. parvum |
| Binomial | Cryptosporidium parvum |
Contents |
[edit] Surface Characteristics
C. parvum possesses numerous surface glycoproteins thought to play a role in pathogenesis. An immunodominant >900kDa protein, known as GP900, localizes to the apical end of sporozoites and in micronemes of merozoites. Its high molecular mass is most likely due to heavy post-translational glycosylation. Indeed, the structure of GP900 is similar to that of a family of glycoproteins known as mucins. GP900 is thought to mediate attachment and invasion to host cells. GP900 may also play a role in C. parvum’s resistance to proteolysis by the numerous proteases found in the mammalian gut.
In vitro, hyperimmune sera as well as antibodies directed at specific epitopes on the GP900 protein inhibit the invasion of C. parvum sporozoites into MDCK cell monolayers. Additionally, competitive inhibition using native GP900 or purified GP900 fragments reduces cell invasion.
Further experiments have confirmed the importance of the mucin-like glycosylations. Lectins directed at GP900 carbohydrate moieties (alpha-N-galactosamine) were able to block adhesion and prevent C. parvum invasion.
C. parvum glycoproteins have the characteristics of attractive vaccine candidates. Many are immunodominant, and antibodies against select domains block invasion of host cells.
[edit] Transmission
Infection is caused by ingestion of sporulated oocysts transmitted by the fecal-oral route. In healthy human hosts, the median infective dose is 132 oocysts. The general C. parvum life cycle is shared by other members of the genus. Invasion of the apical tip of ileal enterocytes by sporozoites and merozoites causes pathology seen in the disease.
[edit] Pathogenic Activity
It causes cryptosporidiosis, a parasitic disease of the mammalian intestinal tract. C. parvum infection is of particular concern in immunocompromised patients, where diarrhea can reach 10–15L per day. Other symptoms may include anorexia, nausea/vomiting and abdominal pain.
