Stage-specific processing of Pfs230, a Plasmodium falciparum transmission-blocking vaccine candidate

During Plasmodium falciparum gametocytogenesis, Pfs230, a malaria transmission-blocking vaccine candidate, is expressed as a 360 kDa protein localized to the parasitophorous vacuole/parasite plasma membrane. When gametocytes emerge from red blood cells, as they do when taken up in a blood meal by a mosquito, Pfs230 is processed from a 360 kDa form to a 310 kDa form the latter of which is exposed on the exterior surface of gametes. The 50 kDa portion of Pfs230, removed from the amino-terminus of the 360 kDa form, contains 25 contiguous glutamates and an EEVG(16) repeat. Analogous to other P. falciparum proteins, the repeat region appears to be immunodominant. As the gamete emerges from the red blood cell and is exposed to the antibodies in the blood meal, cleavage of the immunodominant region of Pfs230 may contribute to an immune evasion strategy by the parasite.