Assessing the functional impact of PfRh5 genetic diversity on ex vivo erythrocyte invasion inhibition

Abstract

The PfRh5-Basigin ligand–receptor interaction is an essential step in the merozoite invasion process and represents an attractive vaccine target. To reveal genotype–phenotype associations between naturally occurring allelic variants of PfRh5 and invasion inhibition, we performed ex vivo invasion inhibition assays with monoclonal antibodies targeting basigin coupled with PfRh5 next-generation amplicon sequencing. We found dose-dependent inhibition of invasion across all isolates tested, and no statistically significant difference in invasion inhibition for any single nucleotide polymorphisms. This study demonstrates that PfRh5 remains highly conserved and functionally essential, even in a highly endemic setting, supporting continued development as a strain-transcendent malaria vaccine target.

Identification of novel genetic variants in the malaria vaccine candidate PfRh5: structure-guided insights into potential function

“…This was observed with certain SNPs, such as D249G and H170R being found in Dalaba, Mako, and Camp Militaire. C203Y was the only SNP found across all sites, which is expected given our previous documentation of its high prevalence in the region 16 and in other regions of Senegal 17 . Overall, the sample size from each clinic does not truly permit quantitative comparisons of genetic diversity between sites; however some of these trends are interesting and would warrant further investigation in prospective targeted studies.…”

“…Overall, 158/189 (83.59%) of the isolates contained at least one mutant allele of PfRh5, relative to the 3D7 reference genome (Figure 2A, Supplementary Figure 1). In total, 90 non-synonymous SNPs were identified from these sequences, of which, only 8 were previously reported in other studies 14,[17][18][19] , and an additional 8 were identified in our previously published data 16 . Of the 74 novel SNPs reported here for the first time, 6 were previously described at the same position but we observed different amino acid substitutions (D52G, D127G, D379G, E362A, T384A, and Y147C) (Figure 2A); Supplementary Table 1).…”

“…Of the 74 novel SNPs reported here for the first time, 6 were previously described at the same position but we observed different amino acid substitutions (D52G, D127G, D379G, E362A, T384A, and Y147C) (Figure 2A); Supplementary Table 1). We include the 31 samples in our previously published genotype-phenotype association study 16 among the 189 total here to allow for a 2/11 more complete assessment of population prevalence of SNPs in PfRh5. Of the 90 SNPs reported here, 8 were present in more than one isolate, while the bulk 82/90 (91%) were singletons (detected in only individual samples) (Figure 1).…”

“…The genetic diversity that has thwarted the efficacy of previous malaria vaccines is traditionally not specifically evaluated until well into clinical trials 2 . Previous research has shown PfRh5 to be relatively conserved, with 43 non-synonymous polymorphisms (NS SNPs) documented between published and unpublished data [14][15][16][17][18][19] . Of these documented SNPs, only five have been shown to be present at frequencies above 10% in any given population, and only one (S197Y) has been shown to contribute to immune evasion from a neutralizing monoclonal antibody 20,21 .…”

“…In this work, we seek to do just that. We sampled from active cases in Kédougou, Senegal, a highly endemic region already known to contain unique genotypes 16 .…”