Antibody Response Profiles Induced by Plasmodium Falciparum Glutamate-Rich Protein in Naturally Exposed Individuals From a Brazilian Area Endemic for Malaria

Abstract

The goal of this study was to evaluate the antibody response induced by Plasmodium falciparum glutamate-rich protein (GLURP) in naturally exposed individuals from the Brazilian Amazon region (Rondonia State). The results showed that most individuals had IgG against two well-defined regions within P. falciparum GLURP, the relatively conserved N-terminal nonrepeat region (R0) and the immunodominant repeat region (R2), 67% and 79%, respectively. The peptides S4 from R2 (53%) and P11 from R0 (49%) were identified as immunodominant B cell epitopes and induced higher levels of antibodies. The number of GLURP peptides recognized and the levels of IgG against S4 and P11 peptides showed a positive correlation with age and time of exposure in the malaria-endemic area studied. The antibody responses against GLURP epitopes appear to be modulated by HLA class II antigens. Interestingly, the GLURP immunodominant B cell epitopes in individuals from a Brazilian malaria-endemic area are distinguishable from those of the African malaria-endemic area. Considering the importance of GLURP as a malaria vaccine candidate and the increasing focus on the use of subunit vaccines in the control of infectious diseases, the concern of the influence of class II allele frequencies in ethnically diverse populations may be important before vaccine trials are conducted among people naturally exposed to malaria parasites.

Naturally acquired humoral and cellular immune responses to Plasmodium vivax merozoite surface protein 9 in Northwestern Amazon individuals

“…The IgG reactivity index to PvMSP9-RIRII and PvMSP9-RII correlated positively with time of residence in endemic region in both localities while correlation with age was observed only in Ribeirinha and the number of previous episodes of malaria only in Colina. The association between antibody responses with age and time of residence in endemic region is a phenomenon which has been frequently reported for various antigens [28, 29, 33, 34], reflecting most likely exposure to malaria parasite and possibly maturation of the immune system over time. However, since in our study mainly adults were studied, age related changes in antibody responses in Ribeirinha could reflect length of exposure as age in this native population represents time of exposure in an endemic region.…”

“…Samples and survey data were collected during the dry months of June–August of 2004, coinciding with the period of increased malaria transmission in Rondonia State. The two communities of Colina and Ribeirinha have been described previously [28, 29]. Briefly, Colina consists primarily of transmigrants from non-endemic areas of Brazil (63.8%) who have lived in the region for 10 years or more.…”

Evolution and selection of human leukocyte antigen alleles by Plasmodium falciparum infection

“…It was suggested that HLADRB1*1302 should contain a tyrosine residue as a major anchor in the glyb86-containing pocket for binding; this particular immunodominant malaria antigen epitope will not be able to bind to DRB1*1301 with a Val-b86-containing pocket, as was the case in in vitro studies [21]. The P. falciparum glutamate-rich protein (GLURP) antigen response to a naturally exposed Brazilian population is HLA restricted ( [23], Table 2) and different malarial antigens demonstrate differing HLA restriction. EBA-175 antigen is used by P. falciparum to bind to red cells [26] and a conserved peptide 1815 from this protein plays an important role in this invasion.…”

“…These studies supplement the HLA data from populations resistant to P. falciparum malaria. HLA-B53 can efficiently present certain malaria antigens in a Gambian population to generate cytotoxic T lymphocytes [23]. HLA-B35 is associated with resistance to severe malaria in several populations [20].…”

Antibodies against the Plasmodium falciparum glutamate-rich protein from naturally exposed individuals living in a Brazilian malaria-endemic area can inhibit in vitro parasite growth

“…In this context, several proteins have been identified and selected as candidate molecules for use in the composition of a malaria vaccine. Among these, the P. falciparum glutamate-rich protein (GLURP) appears to be a promising candidate (Hogh et al 1992, Dziegiel et al 1993, Theisen et al 1998, Pratt-Riccio et al 2005.…”