Hammondia

Hammondia is a genus of parasitic alveolates in the phylum Apicomplexa.

Hammondia
Scientific classification
Domain:
Eukaryota
(unranked):
Sar
(unranked):
Alveolata
Phylum:
Apicomplexa
Class:
Conoidasida
Subclass:
Coccidiasina
Order:
Eucoccidiorida
Suborder:
Eimeriorina
Family:
Sarcocystidae
Subfamily:
Toxoplasmatinae
Genus:
Hammondia
Species

Hammondia hammondi
Hammondia pardalis

History

This genus was created in 1975. Before this date the species of this genus were confused with Toxoplasma gondii to which they are closely related.[1]

The canid-infecting species, H. heydorni and H. triffittae, have been split into new genus Heydornia based on the molecular phylogenetic analysis.[2]

Life cycle

The species in this genus have two vertebrate hosts in their life cycle: a felid (the definitive host) and prey species (the intermediate host), which vary and depend on the local fauna but include mice, deer and others.

In the gastrointestinal tract of the definitive host the parasite undergoes sexual reproduction, forms a zygote which after some divisions forms a cyst that is excreted. The cyst is subsequently ingested by the prey species in whom the parasite decysts and invades its tissues wherein it again multiplies and encysts. After ingestion of the tissues of the prey species by the definitive host the parasite again decysts and multiplies. It also undergoes sexual reproduction before encysting again.

Genome

The genome of Hammondia hammondi has been sequenced.[3]

References
  1. Dubey JP, Sreekumar C (2003). "Redescription of Hammondia hammondi and its differentiation from Toxoplasma gondii". Int. J. Parasitol. 33 (13): 1437–53. doi:10.1016/S0020-7519(03)00141-3. PMID 14572507.
  2. Ogedengbe; et al. (2016). "Molecular phylogenetic analyses of tissue coccidia (sarcocystidae; apicomplexa) based on nuclear 18s RDNA and mitochondrial COI sequences confirms the paraphyly of the genus Hammondia". Parasitology Open. 2: e2. doi:10.1017/pao.2015.7.
  3. Walzer KA, Adomako-Ankomah Y, Dam RA, Herrmann DC, Schares G, Dubey JP, Boyle JP (2013). "Hammondia hammondi, an avirulent relative of Toxoplasma gondii, has functional orthologs of known T. gondii virulence genes". Proc. Natl. Acad. Sci. U.S.A. 110 (18): 7446–51. doi:10.1073/pnas.1304322110. PMC 3645575. PMID 23589877.


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