Plasmodium falciparum genomic surveillance: Prevalence of pfhrp2 and pfhrp3 gene deletions in endemic areas of Brazil

Rapid malaria diagnostic tests (RDTs), used in difficult-to-reach areas, are based on the identification of specific antigens of Plasmodium spp. and they have been very useful for the diagnosis of species fundamental for the elimination of the disease. The most common are RDTs based on the P. falciparum HRP2 antigen. The HRP3 antigen, also present in P. falciparum, is a structural analogue of the HRP2 antigen and therefore can cross-react with HRP2 in these tests. The HRP2 antigen is expressed by the pfhrp2 gene, while the HRP3 antigen is expressed by the pfhrp3 gene. There is a growing number of studies that report deletions of the pfhrp2 and pfhrp3 genes in natural populations of P. falciparum in several endemic countries for malaria, including countries bordering Brazil. Confirming the presence of parasites with these deletions in endemic areas of the country is fundamental, since individuals infected with P. falciparum with deletion of the pfhrp2/3 genes may present false negative results in the RDT. Previous study showed, in 82 samples of P. falciparum from the laboratory biorepository, a frequency of 34.5% of exclusive deletion of the pfhrp2 gene, 23.2% of exclusive deletion of the pfhrp3 gene and 18.3% of with double deletion. 500 samples of symptomatic and asymptomatic individuals infected with P. falciparum collected during the service’s epidemiological surveillance actions will be analyzed. The diagnosis of Plasmodium spp. will be performed through thick smear and confirmed by detection of the 18S rRNA gene by PCR. DNA quality control will be performed by amplification of pfmsp1 and pfmsp2 genes. Detection of the pfhrp2 and pfhrp3 genes will be performed according to protocols published and well standardized by the WHO.

Project details

Diagnostics

Jul 2021

Brazil

Malaria Molecular Surveillance (MMS)