Characterisation and sequence of a protective rhoptry antigen from Plasmodium falciparum

Ridley, Robert G.; Takács, B.; Lahm, Hans‐Werner; Delves, C. J.; Goman, Michael; Certa, Ulrich; Matile, Hugues; Woollett, Gillian R.; Scaife, John

doi:10.1016/0166-6851(90)90103-s

Cited by 85 publications

(65 citation statements)

References 30 publications

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“…The presence of the 140-kDa protein in the purified PyAMA-1 suggests that AMA-1 has the potential to interact with another putative rhoptry protein and form a noncovalent association. Two other protein complexes have been described in P. falciparum rhoptries (24): the highmolecular-mass rhoptry protein complex (21) and the lowmolecular-mass rhoptry protein complex containing rhoptryassociated proteins 1 and 2 (38,40). The association between the two P. yoelii yoelii molecules appears to be dynamic given that they may copurify using an AMA-1 specific MAb and yet may be independently distributed from the rhoptries to other cellular locations.…”

Section: Discussionmentioning

confidence: 99%

Immunization with Parasite-Derived Apical Membrane Antigen 1 or Passive Immunization with a Specific Monoclonal Antibody Protects BALB/c Mice against Lethal Plasmodium yoelii yoelii YM Blood-Stage Infection

Narum¹,

Ogun²,

Thomas

et al. 2000

Infect Immun

101

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We have purified apical merozoite antigen 1 (AMA-1) from extracts of red blood cells infected with the rodent malaria parasite Plasmodium yoelii yoelii YM. When used to immunize mice, the protein induced a strong protective response against a challenge with the parasite. Monoclonal antibodies specific for P. yoelii yoelii AMA-1 were prepared, and one was very effective against the parasite on passive immunization. A second protein that appears to be located in the apical rhoptry organelles and associated with AMA-1 was identified.Early studies by Cohen et al. (6) and more recently by Sabchareon et al. (39) demonstrated that passive immunization with purified immunoglobulin obtained from adults living in areas holoendemic for malaria transferred clinical protection against Plasmodium falciparum, the causative agent of the most severe form of malaria. The mechanisms involved in this protective effect of antibody have been analyzed in in vivo and in vitro studies using humans and animal models. With respect to merozoites and erythrocyte (red blood cell [RBC]) invasion, it has been proposed that the protective mechanisms include merozoite neutralization by blocking ligand-receptor interactions or agglutination, the targeting of monocytes to secrete cytotoxic factors in an antibody dependent cell-mediated inhibition (4), and the specific inhibition of essential biochemical events such as the processing of merozoite surface protein 1 (MSP-1) (3).Apical membrane antigen 1 (AMA-1) is a merozoite protein that is a target of immune effector mechanisms that most likely neutralize merozoite invasion. The protein is located in the apical rhoptry organelles of the developing and free merozoite (8) and can be relocated from here to the surface of the parasite. In immunofluorescence studies with specific antibodies, a characteristic punctate pattern is observed, together with a circumferential (merozoite surface) staining pattern (32). This protein was initially identified in the simian malaria parasite P. knowlesi and named PK66 (here called PkAMA-1) (12). Monoclonal antibodies (MAbs) and their Fab fragments specific for PkAMA-1 were inhibitory in in vitro cultures, acting at a point in the parasite's asexual blood-stage development beyond schizont maturation (9, 42). Further evidence that AMA-1 can induce a strong protective immune response has been provided by immunization of nonhuman primates against simian malaria parasites (7, 11) and of mice against P. chabaudi (1). The 83-kDa P. falciparum AMA-1 (PfAMA-1; also named PF83 [35,44]) is well conserved at the primary sequence level compared to the simian and rodent malaria proteins, except for an N-terminal extension in PfAMA-1. The sequence conservation within the AMA-1 family, including the protein in other human (5), nonhuman primate (15, 36, 45), and rodent (25) malaria parasites, suggests that there are strong functional constraints on the structure of this protein.The protein contains a large external ectodomain followed by a transmembrane region and a short cytoplas...

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Section: Discussionmentioning

confidence: 99%

Immunization with Parasite-Derived Apical Membrane Antigen 1 or Passive Immunization with a Specific Monoclonal Antibody Protects BALB/c Mice against Lethal Plasmodium yoelii yoelii YM Blood-Stage Infection

Narum¹,

Ogun²,

Thomas

et al. 2000

Infect Immun

101

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“…Unlike many other P. falciparum antigens, RAP1 and RAP2 exhibit a high degree of sequence similarity among P. falciparum isolates. Isolates from Honduras, Sierra Leone, Tanzania, India, Thailand, The Netherlands, Uganda, and Vietnam have been sequenced for RAP1, and isolates from Honduras, Papua New Guinea, The Netherlands, Uganda, and Vietnam have been sequenced for RAP2 (9,20,21,33,36). Thus, it is thought likely that RAP1 and RAP2 proteins may provide a relatively isolate-independent protective immunity in humans compared to other P. falciparum antigens.…”

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confidence: 99%

Interaction of HLA and Age on Levels of Antibody toPlasmodium falciparumRhoptry-Associated Proteins 1 and 2

Johnson¹,

Leke

Harun

et al. 2000

Infect Immun

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The Plasmodium falciparum rhoptry-associated proteins 1 and 2 (RAP1 and RAP2) are candidate antigens for a subunit malaria vaccine. The design of the study, which looks at the acquisition of immunity to malaria from childhood to old age, has allowed us to document the interaction of HLA and age on levels of antibody to specific malarial antigens. Antibodies reach maximum levels to RAP1 after the age of 15 but to RAP2 only after the age of 30. The effect of HLA-DRB1 and -DQB1 and age on levels of antibody to rRAP1 and rRAP2 was analyzed with a multiple regression model in which all HLA alleles and age were independent variables. DQB1*0301 and -*03032 showed an age-dependent association with levels of antibody to rRAP1, being significant in children 5 to 15 years (P < 0.001) but not in individuals over 15 years of age. DRB1*03011 showed an age-dependent association with antibody levels to rRAP2; however, this association was in adults over the age of 30 years (P < 0.01) but not in individuals under the age of 30 years. No associations were detected between DRB1 alleles and RAP1 antibody levels or between DQB1 alleles and RAP2 antibody levels. Thus, not only the HLA allele but also the age at which an interaction is manifested varies for different malarial antigens. The interaction may influence either the rate of acquisition of antibody or the final level of antibody acquired by adults.The rhoptry-associated proteins 1 and 2 (RAP1 and RAP2) form a low-molecular-mass complex located in the rhoptries of Plasmodium falciparum (5, 9). The rhoptries are a pair of organelles at the apical end of the parasite that are involved in the invasion of erythrocytes; thus, molecules in the rhoptries were among the first components identified as potential candidates for a subunit vaccine. Subsequent studies have borne out this potential. Monoclonal antibodies (MAbs) directed against rhoptry-associated proteins have been shown to provide substantial inhibition of parasite invasion in vitro (7,17,19,22,29,37). In addition, protein preparations containing both RAP1 and RAP2 have been used to immunize Saimiri monkeys. In these studies, the immunized monkeys developed a lower peak parasitemia than nonimmunized controls and were protected from subsequent lethal blood-stage challenge with P. falciparum (9,30,32,34) in a way similar to the protection acquired by immunization with whole merozoite (27,39,46). Two rhoptry-associated proteins, RAP1 and RAP2, have been sequenced (20,36). Unlike many other P. falciparum antigens, RAP1 and RAP2 exhibit a high degree of sequence similarity among P. falciparum isolates. Isolates from Honduras,

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“…The truncated form of RAP1 was able to traffic to the rhoptries; however, RAP2 was apparently retained in the endoplasmic reticulum (ER). This suggests that a function of RAP1 is to act as an escorter protein of RAP2 to the rhoptries in P. falciparum (4).The RAP1 and RAP2 genes have been characterized and sequenced (41,42), but the RAP3 gene has yet to be identified. In this report, we describe the gene encoding RAP3 and show that this protein is closely related to RAP2.…”

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Identification and Disruption of the Gene Encoding the Third Member of the Low-Molecular-Mass Rhoptry Complex in Plasmodium falciparum

et al. 2002

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The low-molecular-mass rhoptry complex of Plasmodium falciparum consists of three proteins, rhoptryassociated protein 1 (RAP1), RAP2, and RAP3. The genes encoding RAP1 and RAP2 are known; however, the RAP3 gene has not been identified. In this study we identify the RAP3 gene from the P. falciparum genome database and show that this protein is part of the low-molecular-mass rhoptry complex. Disruption of RAP3 demonstrated that it is not essential for merozoite invasion, probably because RAP2 can complement the loss of RAP3. RAP3 has homology with RAP2, and the genes are encoded on chromosome 5 in a head-to-tail fashion. Analysis of the genome databases has identified homologous genes in all Plasmodium spp., suggesting that this protein plays a role in merozoite invasion. The region surrounding the RAP3 homologue in the Plasmodium yoelii genome is syntenic with the same region in P. falciparum; however, there is a single gene. Phylogenetic comparison of the RAP2/3 protein family from Plasmodium spp. suggests that the RAP2/3 duplication occurred after divergence of these parasite species.The merozoite form of the asexual life cycle in the blood stage of Plasmodium spp. attaches to the surface of the erythrocyte, thus initiating the invasion process (23). Ultrastructural and biochemical studies of merozoites have suggested that the rhoptries play an essential role in the invasion process. These electron-dense organelles, part of the apical complex, are connected to the surface of the apical end of the merozoite by a duct-like structure, and their contents are expelled during erythrocyte invasion (1). Proteins located on the surface of merozoites and those released from the apical organelles, the rhoptries and micronemes, are exposed to the immune system. Consequently, these proteins are potential vaccine candidates, and there is considerable interest in the identification and characterization of proteins in these organelles (2).A number of proteins located in the rhoptries have been identified and characterized, such as the low-molecular-mass rhoptry protein complex of Plasmodium falciparum (28). This complex consists of various polypeptides, ranging in size from 86 to 37 kDa, that are immunoprecipitated by antibodies to rhoptry-associated protein 1 (RAP1) (7,11,29,43). Several studies established that the largest product, reported to be 86 kDa, is a short-lived precursor of the 82-kDa RAP1 protein and that this 82-kDa protein is further processed to a 67-kDa protein (7,26,27,29). The 42-kDa protein (also reported as 39 kDa) was found to be the product of a second gene, RAP2 (7,11,28,39,42). Debate remained regarding the origin of the 40-kDa (or 37-kDa) protein also immunoprecipitated as a part of the RAP1 complex. It was suggested that this protein was a breakdown product of either RAP1 or RAP2 (41). It was subsequently shown, however, that RAP1, RAP2, and RAP3 yield different V8 protease cleavage patterns and are thus products of three distinct genes (28). The RAP2 and RAP3 proteins, in particular, were hypothesiz...

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Characterisation and sequence of a protective rhoptry antigen from Plasmodium falciparum

Cited by 85 publications

References 30 publications

Immunization with Parasite-Derived Apical Membrane Antigen 1 or Passive Immunization with a Specific Monoclonal Antibody Protects BALB/c Mice against Lethal Plasmodium yoelii yoelii YM Blood-Stage Infection

Immunization with Parasite-Derived Apical Membrane Antigen 1 or Passive Immunization with a Specific Monoclonal Antibody Protects BALB/c Mice against Lethal Plasmodium yoelii yoelii YM Blood-Stage Infection

Interaction of HLA and Age on Levels of Antibody toPlasmodium falciparumRhoptry-Associated Proteins 1 and 2

Identification and Disruption of the Gene Encoding the Third Member of the Low-Molecular-Mass Rhoptry Complex in Plasmodium falciparum

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