Protozoa apicomplexa

Entzeroth, R., Dubremetz, J. F., Hodick, D. and Ferreira, E. (1986) Immunoelectromicro-scopic demonstration of the exocytosis of dense granules contents into the secondary parasitophorous vacuole of Sarcocystis muris (Protozoa, Apicomplexa). Eur. J. Cell Biol. 41 182-188. 

Perkins, F. O. (1991), Sporozoa Apicomplexa, Microsporidia, Haplosporidia, Paramyxea, Myx-osporidia and Actinosporidia, in F. W. Harrison andj. O. Corliss (Eds), Microscopic Anatomy of Invertebrates Protozoa, Vol. 1., Wiley-Liss, New York, pp. 261-331-... 

Ellis TJ, Morrison DA, Jeffries AC (1998) The phylum Apicomplexa an update on the molecular phlogeny. In Coombs GC, Vickerman K, Sleigh MA, Warren A (eds) Evolutionary Relationships among the Protozoa. Kluwer, Boston, pp 255-274... 

Intracellular protozoa of the phylum Apicomplexa such as plasmodium, toxoplasma, and eimeria have long been known to respond to sulfonamides and sulfones. This has led to the assumption that Apicomplexa must synthesize their own folate in order to survive. The reaction of 2-amino-4-hydroxy-6-hydroxymethyl-dihydropteridine diphosphate with />aminobenzoate to form 7,8-dihydropteroate has been demonstrated in cell-free extracts of the human malaria parasite Plasmodium falciparum. 2-Amino-4-hydroxy-6-hydroxymethyl-dihydropteridine pyrophosphokinase and 7,8-dihydropteroate synthase have also been identified. Sulfathiazole, sulfaguanidine, and sulfanilamide act as competitive inhibitors of p-aminobenzoate. It has not been possible to demonstrate dihydrofolate synthase activity in the parasites, which raises the possibility that 7,8-dihydropteroate may have substituted for dihydrofolate in malaria parasites. Similar lack of recognition of folate as substrate was also observed in the dihydrofolate reductase of Eimeria tenella, a parasite of chickens. 

Apicomplexa Protozoa Plasmodium, Toxoplasma, Malaria, coccidiosis, abortion,... 

---