Extent and Dynamics of Polymorphism in the Malaria Vaccine Candidate Plasmodium falciparum Reticulocyte-Binding Protein Homologue-5 in Kalifabougou, Mali
JournalAmerican Journal of Tropical Medicine and Hygiene
PublisherAmerican Society of Tropical Medicine and Hygiene
MetadataShow full item record
AbstractReticulocyte-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 ofRH5in 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 (p = 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. Copyright Copyright 2018 by The American Society of Tropical Medicine and Hygiene.
SponsorsThis work was supported by the Howard Hughes Medical Institute; the U.S. National Institutes of Health (U19AI110820 and U01AI065683 from the National Institute of Allergy and Infectious Diseases [NIAID]; and grant D43TW001589 from the Fogarty International Center) and the Intramural Research Program of the Division of Intramural Research at NIAID. T. M. T. was supported by grants from the National Center for Advancing Translational Sciences, Clinical and Translational Sciences (UL1TR001108) and from NIAID (K08AI125682). S. T.-H. is supported by a grant from the National Institutes of Health (R01AI101713).
Identifier to cite or link to this itemhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85049659754&doi=10.4269%2fajtmh.17-0737&partnerID=40&md5=3edfb1894e3181cfa619d32e35e82267; http://hdl.handle.net/10713/9692