Proposed ligands include merozoite surface proteins or proteins situated in micronemes and rhoptries of merozoite

Proposed ligands include merozoite surface proteins or proteins situated in micronemes and rhoptries of merozoite. TheseP. of PfEBA-175II F2 and Epidermal Growth Factor Receptor Peptide (985-996) PfCP-2.9 did not result in antigen (Ag) competition in animals. Moreover, antibodies to both PfEBA-175II F2 and PfCP-2.9, isolated from rabbits immunized with both constructs, inhibited parasite growth in vitro. The combination of high yield, functional Epidermal Growth Factor Receptor Peptide (985-996) folding, antibody inhibition, and lack of Ag competition provides support for inclusion of these merozoite proteins in a combination vaccine against infection with blood-stage parasites. Plasmodium falciparumandPlasmodium vivaxare the causative agents of the majority of malaria cases in the world today. Of the two,P. falciparumis responsible for the most virulent form of the disease, causing over 2 million deaths per year, usually in children under 5 years of age. Malaria infections have traditionally been treated by chemotherapy. Another approach has been to use insecticides against theAnophelessp. mosquito vectors that transfer the parasites between hosts. Because of the emergence and rapid spread of drug-resistant parasites and insecticide-resistant mosquitoes, there is an urgent need for the development of new tools to control malaria. Vaccination is one such tool that may control and even eradicate Dig2 the disease from the world. Based on the life cycle of the parasite, merozoite invasion of host erythrocytes is an optimal target for vaccines against infection with blood-stage parasites. However, merozoite invasion is a complex process involving several steps. The initial step requires species-specific interactions between erythrocyte receptors and parasite ligands. Disruption of these interactions would, in principle, prevent invasion and all of the clinical manifestations of infection. The invasion of human erythrocytes byP. vivaxrequires recognition of the Duffy blood group antigen (Ag) (11,22), while invasion byP. falciparuminvolves multiple alternative ligand-receptor interactions (5,9,14). Glycophorin A and band 3 on human erythrocytes are thought to be receptors for invasion ofP. falciparum. Epidermal Growth Factor Receptor Peptide (985-996) Proposed ligands include merozoite surface Epidermal Growth Factor Receptor Peptide (985-996) proteins or proteins situated in micronemes and rhoptries of merozoite. TheseP. falciparumligands and receptors interact via either a sialic acid-dependent or an independent invasion pathway. OneP. falciparumligand is the 175-kDa erythrocyte binding Ag (EBA-175), which is released as a soluble protein from micronemes at the time of schizont Epidermal Growth Factor Receptor Peptide (985-996) rupture (3). A number of investigations indicate that the protein specifically binds to normal human erythrocytes but does not bind to erythrocytes that are deficient in glycophorin A or that have been treated with neuraminidase (21). An N-terminal cysteine-rich region comprised of 616 amino acids, known as region II (RII), has been identified as the receptor-binding domain of EBA-175 (25). The sequence of RII is conserved amongP. falciparumisolates (13) and is also homologous to the cysteine-rich erythrocyte binding domains of theP. vivaxDuffy binding proteins (1). RII is composed of two subdomains, designated F1 and F2. Investigation of the subdomains has revealed that the binding function resides within the F2 subdomain. Antibodies against this subdomain blocked the binding of the molecule to glycophorin A on erythrocytes as well as parasite invasion in vitro (6,17,20). The dependence on the binding of glycophorin A for invasion places this interaction in the sialic acid-dependent invasion pathway. Merozoite surface protein 1 (MSP1) is spread evenly over the entire surface of the merozoite and may be anchored via epidermal growth factor-like regions in the C terminus of the protein (7). Upon invasion, the proteolytic cleavage just N terminal of these epidermal growth factor-like domains.