Adhesiveness Properties and Immunogenicity of VIR proteins in vivax malaria

Background: One of the best adhesive phenomena associated with the pathogenesis of P. falciparum malaria is the adhesion of parasitized erythrocytes. Parasites can adhere to endothelial cells or to uninfected erythrocytes, thereby forming a rosette. In malaria caused by P. falciparum this adhesive phenotype is commonly associated with severity of infection. However, in vivax malaria little is known about rosette formation or other adhesive phenomenon. It was recently demonstrated that P. vivax adheres to Glycophorin C receptor present on erythrocytes.However, the parasitic binder in this interaction is unknown. There are evidences that this interaction would be mediated by VIR proteins, which are polymorphic proteins encoded by a multigene family named vir.Methods: Three VIR recombinant proteins were expressed in E. coli and CHO cells. Binding assays with recombinant VIR proteins and non-infected red blood cell as well endothelial receptors were performed. The IgG and IgM antibody response against recombinant VIR proteins were evaluated. Results and Conclusions: We showed that VIR proteins were able to mediate the binding to ICAM-1 endothelial receptor and this binding was inhibiting by specific VIR antibodies. We also observed the binding of VIR proteins to non-infected red blood cells however that was dependent of plasma. About 20% of analyzed samples had IgG antibodies to at least one of the VIR proteins here analyzed. Here we showed the adhesive properties of three VIR proteins and their immunogenicity. Understanding the pathogenesis of the parasite may lead to the development of new strategies for malaria control.