THE PF332 GENE CODES FOR A MEGADALTON PROTEIN OF PLASMODIUM-FALCIPARUM ASEXUAL BLOOD STAGES

We characterized the Plasmodium falciparum antigen 332 (Ag332) which i s specifically expressed during the asexual intraerythrocytic cycle of the parasite. The corresponding Pf332 gene has been located in the su btelomeric region of chromosome 11. Furthermore, it is present in all strains so far analyzed and shows marked restriction length fragment p olymorphism. Partial sequence and restriction endonuclease digestion o f cloned fragments revealed that the Pf332 gene is composed of highly degenerated repeats rich in glutamic acid. Mung been nuclease digestio n and Northern blot analysis suggested that the Pf332 gene codes for a protein of about 700 kDa. These data were further confirmed by Wester n blot and immunoprecipitation of parasites extracts with an antiserum raised against a recombinant clone expressing part of the Ag332. Conf ocal immunofluorescence showed that Ag332 is translocated from the par asite to the surface of infected red blood cells within vesicle-like s tructures. In addition, Ag332 was detected on the surface of monkey er ythrocytes infected with Plasmodium falciparum.