Abstract
BackgroundThe Plasmodium falciparum Erythrocyte Binding Antigen-175 (EBA-175) is an antigen considered to be one of the leading malaria vaccine candidates. EBA-175 mediates sialic acid-dependent binding to glycophorin A on the erythrocytes playing a crucial role during invasion of the P. falciparum in the host cell. Dimorphic allele segments, termed C-fragment and F-fragment, have been found in high endemicity malaria areas and associations between the dimorphism and severe malaria have been described. In this study, the genetic dimorphism of EBA-175 was evaluated in P. falciparum field isolates from Brazilian malaria endemic area.MethodsThe study was carried out in rural villages situated near Porto Velho, Rondonia State in the Brazilian Amazon in three time points between 1993 and 2008. The allelic dimorphism of the EBA-175 was analysed by Nested PCR.ResultsThe classical allelic dimorphism of the EBA-175 was identified in the studied area. Overall, C-fragment was amplified in a higher frequency than F-fragment. The same was observed in the three time points where C-fragment was observed in a higher frequency than F-fragment. Single infections (one fragment amplified) were more frequent than mixed infection (two fragments amplified).ConclusionsThese findings confirm the dimorphism of EBA175, since only the two types of fragments were amplified, C-fragment and F-fragment. Also, the results show the remarkable predominance of CAMP allele in the studied area. The comparative analysis in three time points indicates that the allelic dimorphism of the EBA-175 is stable over time.
Highlights
The Plasmodium falciparum Erythrocyte Binding Antigen-175 (EBA-175) is an antigen considered to be one of the leading malaria vaccine candidates
EBA175 is localized in the micronemes in the terminal end of the merozoite and has been well characterized as the ligand that binds glycophorin A, present in the erythrocytes membrane [11]
The goal of this study was to evaluate the genetic dimorphism of the EBA-175 in P. falciparum isolates from Rondonia State, a Brazilian malaria endemic area
Summary
The Plasmodium falciparum Erythrocyte Binding Antigen-175 (EBA-175) is an antigen considered to be one of the leading malaria vaccine candidates. This dimorphism is characterized by the insertion of a segment of 423 base pairs (bp) in strain FCR3 (F-fragment) or a segment of 342 bp in strain CAMP (C-fragment) These two variants are conserved among strains of P. falciparum, and considering that the merozoites are haploid and eba-175 is a single copy gene, either one or the other segment is present in a uniclonal infection [12,13,14]. The role of this dimorphism in the host-parasite interactions, for example potential difference in efficiency of red blood cell invasion related to genotype, remains unclear [15]. It has been documented that the binding of region II of the EBA175 molecule to the sialic acid from glycophorin A, is following by proteolitic cleavage of EBA175 and binding of the dimorphic C and F segments to the glycophorin backbone [12,16]
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