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1.
J Parasitol ; 96(1): 225-7, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19799492

RESUMO

Plasmodium vivax is the second leading cause of malaria worldwide. Invasion of human erythrocytes by P. vivax merozoites is dependent upon the interaction between the parasite Duffy binding protein (PvDBP) and the erythrocyte Duffy antigen receptor. Therefore, disruption of this vital interaction is an attractive target for therapeutic intervention. Although Aotus nancymaae is a commonly used primate model for human P. vivax infections, it has not been confirmed that the interaction between Ao. nancymaae erythrocytes and P. vivax is Duffy antigen dependent. Our results indicate that normal Ao. nancymaae erythrocytes readily bind to PvDBPII and that this binding is completely abolished with chymotrypsin treatment of the erythrocytes. Furthermore, the results of our inhibition assays show a dose-dependent decrease in binding with increasing amounts of anti-PvDBPII polyclonal rabbit sera or anti-Fy6 monoclonal antibody. These data indicate that the interaction between Ao. nancymaae erythrocytes and P. vivax DBPII is Duffy antigen dependent, validating this model system for in vivo studies of anti-PvDBP inhibition.


Assuntos
Antígenos de Protozoários/metabolismo , Aotidae/parasitologia , Eritrócitos/parasitologia , Plasmodium vivax/metabolismo , Proteínas de Protozoários/metabolismo , Receptores de Superfície Celular/metabolismo , Animais , Antígenos de Protozoários/efeitos dos fármacos , Antígenos de Protozoários/imunologia , Aotidae/sangue , Quimotripsina/farmacologia , Relação Dose-Resposta Imunológica , Humanos , Soros Imunes/imunologia , Proteínas de Protozoários/efeitos dos fármacos , Proteínas de Protozoários/imunologia , Coelhos , Receptores de Superfície Celular/efeitos dos fármacos , Receptores de Superfície Celular/imunologia
2.
Clin Exp Immunol ; 156(3): 502-10, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19438604

RESUMO

The Duffy binding protein of Plasmodium vivax (DBP) is a critical adhesion ligand that participates in merozoite invasion of human Duffy-positive erythrocytes. A small outbreak of P. vivax malaria, in a village located in a non-malarious area of Brazil, offered us an opportunity to investigate the DBP immune responses among individuals who had their first and brief exposure to malaria. Thirty-three individuals participated in the five cross-sectional surveys, 15 with confirmed P. vivax infection while residing in the outbreak area (cases) and 18 who had not experienced malaria (non-cases). In the present study, we found that only 20% (three of 15) of the individuals who experienced their first P. vivax infection developed an antibody response to DBP; a secondary boosting can be achieved with a recurrent P. vivax infection. DNA sequences from primary/recurrent P. vivax samples identified a single dbp allele among the samples from the outbreak area. To investigate inhibitory antibodies to the ligand domain of the DBP (cysteine-rich region II, DBP(II)), we performed in vitro assays with mammalian cells expressing DBP(II) sequences which were homologous or not to those from the outbreak isolate. In non-immune individuals, the results of a 12-month follow-up period provided evidence that naturally acquired inhibitory antibodies to DBP(II) are short-lived and biased towards a specific allele.


Assuntos
Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/imunologia , Malária Vivax/imunologia , Plasmodium vivax/imunologia , Proteínas de Protozoários/imunologia , Receptores de Superfície Celular/imunologia , Adulto , Alelos , Animais , Antígenos de Protozoários/genética , Brasil/epidemiologia , Estudos Transversais , DNA de Protozoário/genética , Surtos de Doenças , Humanos , Malária Vivax/epidemiologia , Malária Vivax/parasitologia , Proteína 1 de Superfície de Merozoito/imunologia , Pessoa de Meia-Idade , Plasmodium vivax/genética , Proteínas de Protozoários/genética , Receptores de Superfície Celular/genética , Adulto Jovem
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