Extent and Dynamics of Polymorphism in the Malaria Vaccine Candidate Plasmodium falciparum Reticulocyte-Binding Protein Homologue-5 in Kalifabougou, Mali.

Published

Journal Article

Reticulocyte-binding homologues (RH) are a ligand family that mediates merozoite invasion of erythrocytes in Plasmodium falciparum. Among the five members of this family identified so far, only P. falciparum 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 Pfrh5 gene, resulting in 13 haplotypes encoding unique protein variants. Four of these variants have not been previously observed. Plasmodium falciparum reticulocyte-binding homologue-5 had low amino acid haplotype (h = 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.

Full Text

Duke Authors

Cited Authors

  • Ouattara, A; Tran, TM; Doumbo, S; Adams, M; Agrawal, S; Niangaly, A; Nelson-Owens, S; Doumtabé, D; Tolo, Y; Ongoiba, A; Takala-Harrison, S; Traoré, B; Silva, JC; Crompton, PD; Doumbo, OK; Plowe, CV

Published Date

  • July 2018

Published In

Volume / Issue

  • 99 / 1

Start / End Page

  • 43 - 50

PubMed ID

  • 29848401

Pubmed Central ID

  • 29848401

Electronic International Standard Serial Number (EISSN)

  • 1476-1645

Digital Object Identifier (DOI)

  • 10.4269/ajtmh.17-0737

Language

  • eng

Conference Location

  • United States