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image of Extent and Dynamics of Polymorphism in the Malaria Vaccine Candidate Plasmodium falciparum Reticulocyte–Binding Protein Homologue-5 in Kalifabougou, Mali
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645

Abstract

Reticulocyte-binding homologues (RH) are a ligand family that mediates merozoite invasion of erythrocytes in . Among the five members of this family identified so far, only reticulocyte–binding homologue-5 (PfRH5) has been found to be essential for parasite survival across strains that differ in virulence and route of host-cell invasion. Based on its essential role in invasion and early evidence of sequence conservation, PfRH5 has been prioritized for development as a vaccine candidate. However, little is known about the extent of genetic variability of RH5 in the field and the potential impact of such diversity on clinical outcomes or on vaccine evasion. Samples collected during a prospective cohort study of malaria incidence conducted in Kalifabougou, in southwestern Mali, were used to estimate genetic diversity, measure haplotype prevalence, and assess the within-host dynamics of PfRH5 variants over time and in relation to clinical malaria. A total of 10 nonsynonymous polymorphic sites were identified in the gene, resulting in 13 haplotypes encoding unique protein variants. Four of these variants have not been previously observed. reticulocyte–binding homologue-5 had low amino acid haplotype ( = 0.58) and nucleotide (π = 0.00061) diversity. By contrast to other leading blood-stage malaria vaccine candidate antigens, amino acid differences were not associated with changes in the risk of febrile malaria in consecutive infections. Conserved B- and T-cell epitopes were identified. These results support the prioritization of PfRH5 for possible inclusion in a broadly cross-protective vaccine.

[open-access] This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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/content/journals/10.4269/ajtmh.17-0737
2018-05-29
2018-06-21
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http://instance.metastore.ingenta.com/content/journals/10.4269/ajtmh.17-0737
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  • Published online : 29 May 2018
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