title: Cross-reactive anti-PfCLAG9 antibodies in the sera of asymptomatic parasite carriers of Plasmodium vivax.
abstract: The PfCLAG9 has been extensively studied because their immunogenicity. Thereby, the gene product is important for therapeutics interventions and a potential vaccine candidate. Antibodies against synthetic peptides corresponding to selected sequences of the Plasmodium falciparum antigen PfCLAG9 were found in sera of falciparum malaria patients from Rondônia, in the Brazilian Amazon. Much higher antibody titres were found in semi-immune and immune asymptomatic parasite carriers than in subjects suffering clinical infections, corroborating original findings in Papua Guinea. However, sera of Plasmodium vivax patients from the same Amazon area, in particular from asymptomatic vivax parasite carriers, reacted strongly with the same peptides. Bioinformatic analyses revealed regions of similarity between P. falciparum Pfclag9 and the P. vivax ortholog Pvclag7. Indirect fluorescent microscopy analysis showed that antibodies against PfCLAG9 peptides elicited in BALB/c mice react with human red blood cells (RBCs) infected with both P. falciparum and P. vivax parasites. The patterns of reactivity on the surface of the parasitised RBCs are very similar. The present observations support previous findings that PfCLAG9 may be a target of protective immune responses and raises the possibility that the cross reactive antibodies to PvCLAG7 in mixed infections play a role in regulate the fate of Plasmodium mixed infections.
authors: Centro de Pesquisa em Medicina Tropical, Porto Velho, RO, Brasil. joanadarcneves@hotmail.com
authors: Joana D'Arc Neves
authors: JD
authors: Costa
authors: Fernando Berton
authors: FB
authors: Zanchi
authors: Francisco Lurdevanhe da Silva
authors: FL
authors: Rodrigues
authors: Eduardo Rezende
authors: ER
authors: Honda
authors: Tony Hiroschi
authors: TH
authors: Katsuragawa
authors: Dhélio Batista
authors: DB
authors: Pereira
authors: Roger Lafontaine Mesquita
authors: RL
authors: Taborda
authors: Mauro Shugiro
authors: MS
authors: Tada
authors: Ricardo de Godoi Mattos
authors: Rde G
authors: Ferreira
authors: Luiz Hildebrando
authors: LH
authors: Pereira-da-Silva
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood* / Q000276:immunology*; D000953:Antigens, Protozoan / Q000276:immunology*; D001938:Brazil; D002353:Carrier State; D015815:Cell Adhesion Molecules / Q000276:immunology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000469:parasitology; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000276:immunology* / Q000469:parasitology; D016780:Malaria, Vivax / Q000276:immunology* / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D010963:Plasmodium falciparum / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015815:Cell Adhesion Molecules; D015800:Protozoan Proteins; C407823:clag9 protein, Plasmodium falciparum