Asymptomatic cases of malaria in the Brazilian Amazon: cytoadherence, antibodies against the surface of infected red blood cells and protection in natural infections caused by Plasmodium falciparum.

Author(s)

Alessandra Sampaio Bassi Fratus

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2012-05-04

Examining board members

Gerhard Wunderlich; Fábio Trindade Maranhão Costa; Claudio Romero Farias Marinho; Ariel Mariano Silber; Irene da Silva Soares

• Advisor: Gerhard Wunderlich

Abstract

An important factor in P. falciparum\'s virulence is its ability to adhere to endothelial receptors, mediated by PfEMP1 proteins. In Brazil the number of PfEMP1 variants is limited, severe disease is rare, and there are many individuals carrying the parasite without symptoms. We detected antibodies against the membrane of erythrocytes using plasma of infected individuals from Rondônia, finding only in some cases differences in the immune response, both in frequency and degree; we also could not find differences between the ability to inhibit cytoadherence in static condition. There was no correlation between this capacity and the reactivity index or phenotype; we observed the presence of pan-reactive antibodies that were capable of agglutinating different isolates, but without any difference between ICAM1 and CD36 selected isolates. Taken together, our data indicate the immune response against the infected red blood cell is not decisive for the outcome of malaria suffered by the patients. (AU)