Identification of Plasmodium Falciparum Histidine-Rich Protein Ii and Iii (PFHRP2/3) gene deletions in two communities in southern Ghana: Implications on rapid diagnostic tests

Abstract

Malaria Rapid Diagnostic Tests (RDT’s) have improved malaria diagnosis in highly endemic rural settings. However, the increasingly high false negative rates of Plasmodiumfalciparum histidine-rich protein II (PfHRP2) based RDT kits (PfHRP2-RDT) is a major obstacle to the rapid and reliable diagnosis of malaria. This study was aimed at determining the rate of false-negative RDT as well as the prevalence of P. falciparum parasites with pfhrp2 deletions in selected communities in the Southern Ghana. Whole blood was collected from volunteers living in Obom (high transmission) and Asutsuare(low transmission) and separated into plasma and cell pellet. Genomic DNA was extracted from 310 cell pellets from both sites using the ZymoDNA Kit®. Species-specific 18srRNAPCR was used to identify P.falciparum positive samples. Pfmsp2 and glurp genotyping was used to determine recrudescence or new infection. Good quality DNA samples were then subjected to pfhrp2 exon 1 and PCR as well as pfhrp3 exon 2 PCR. PfHRP2 antigen level was determined using a pfhrp2 Malaria Ag CELISA kit.Microscopy estimation of malaria parasites were 3.3 % of samples from Asutsuare against 39.8 % of Obom samples. The RDTs had 1.7 % of samples from Asutsuare while Obom had 53.4 %. Using 18srRNAPCR for P. falciparum speciation, 59.1 % of the Asutsuare samples tested positive for the malaria parasite whereas 65.8 % of the Obom samples tested positive. Plasmodium falciparum parasites with deletions of both pfhrp2 and pfhrp3 gene were 1.7 % in Obom and 4.8 % in Asutsuare. An R-square value of 0.997 and 0.994 were obtained for Obom and Asutsuare Regression Analysis of ELISA respectively. Deletions of pfhrp2 and pfhrp3 genes were identified in the two study sites and there were higher quantities of PfHRP2 antigens in Obom than in Asutsuare.