Disease relevance of PF14_0102

• We have recently demonstrated that a non-polymorphic rhoptry antigen, RAP-1 (rhoptry associated protein-1), which is recognised by human immune serum, can successfully protect Saimiri monkeys from a lethal infection of Plasmodium falciparum malaria [1].
• We have expressed in Escherichia coli eight recombinant RAP1 proteins representing almost the entire sequence of the mature protein and assessed the antigenicity of the proteins by immunization of mice [2].
• Immunoglobulin G reactivities to rhoptry-associated protein-1 associated with decreased levels of Plasmodium falciparum parasitemia in Tanzanian children [3].

High impact information on PF14_0102

• These results suggest that RAP1 is required to localize RAP2 to the rhoptries, supporting the hypothesis that rhoptry biogenesis is dependent in part on the secretory pathway in the parasite [4].
• Consistent with this were the distinct subcellular localizations of RAP1 and 2 in disrupted RAP1 parasites, where RAP2 does not traffic to the rhoptries but is instead located in a compartment that appears related to the lumen of the endoplasmic reticulum [4].
• In this longitudinal study, recombinant RAP1 (rRAP1) proteins with antigenicity similar to that of P. falciparum-derived RAP1 were used to analyze antibody responses to RAP1 over a period of 4 years (1991 to 1995) of 53 individuals naturally exposed to P. falciparum malaria [5].
• This suggested secondary responses to RAP1 and thus the development of immunological memory for RAP1 [5].
• Specific T-cell recognition of the merozoite proteins rhoptry-associated protein 1 and erythrocyte-binding antigen 1 of Plasmodium falciparum [6].

Biological context of PF14_0102

• However, the anti-RAP1 antibody responses were detected only during or shortly after clinical malarial infections [5].
• The epitope in RAP1 recognised by the antibodies was identified and shown not to be the result of any shared contiguous homologous sequence between the two proteins, but to shared homologous amino acids in critical positions within the epitope [7].
• An oligodeoxyribonucleotide containing one of these (AACGTT), located in the rhoptry associated protein-1 (rap-1) open reading frame, stimulated B cell proliferation [8].
• Focusing on the clinically relevant blood stage of the life cycle, proteomic analysis of proteins labeled with radioactive glucosamine identified GPI anchoring on 11 proteins (merozoite surface protein (MSP)-1, -2, -4, -5, -10, rhoptry-associated membrane antigen, apical sushi protein, Pf92, Pf38, Pf12, and Pf34) [9].

Anatomical context of PF14_0102

• Lymphocytes from a large proportion of the Ghanaian blood donors proliferated in response to the RAP-1 peptide, unlike those of Danish control blood donors, indicating that this sequence contains a malaria-specific T-cell epitope broadly recognized by individuals living in an area with a high transmission rate of malaria [6].
• Specific erythrocyte binding capacity and biological activity of Plasmodium falciparum-derived rhoptry-associated protein 1 peptides [10].
• A peptide derived from a B cell epitope of Plasmodium falciparum rhoptry associated protein 2 specifically raises antibodies to rhoptry associated protein 1 [7].

Associations of PF14_0102 with chemical compounds

• Both brefeldin A (BFA) and low temperature reversibly block the processing of an 86-kDa precursor (Pr86) to the mature 82-kDa RAP-1 product (p82) [11].
• We have also successfully used paraformaldehyde fixation coupled with etching to localise a rhoptry-associated antigen, which is presumably sensitive to glutaraldehyde fixation [12].

Analytical, diagnostic and therapeutic context of PF14_0102

• Immunoprecipitation experiments suggest that truncated RAP1 species did not complex with RAP2 and RAP3 [4].
• We used gene-targeting technology in P.falciparum blood-stage parasites to disrupt the RAP1 gene, producing parasites that express severely truncated forms of RAP1 [4].
• These proteins were then used in enzyme-linked immunosorbent assays to evaluate human antibody responses to RAP1 during naturally transmitted infections in The Gambia [2].
• Epitope mapping with truncated rRAP-1 molecules and overlapping peptides identified the linear RAP-1 sequence Y218KYSL222 as a target of the anti-35.1 MAbs [13].
• The majority of indirect immunofluorescence assay (IFA)-positive MAbs raised against recombinant RAP-1 positions 23 to 711 (rRAP-1(23-711)) recognized epitopes located in the immunodominant N-terminal third of RAP-1 [13].

References