Role of Plasmodium vivax Dihydropteroate Synthase Polymorphisms in Sulfa Drug Resistance

Abstract

Dihydropteroate synthase (DHPS) is a known sulfa drug target in malaria treatment, existing as a bifunctional enzyme together with hydroxymethyldihydropterin pyrophosphokinase (HPPK). Polymorphisms in key residues of Plasmodium falciparum DHPS (PfDHPS) have been characterized and linked to sulfa drug resistance in malaria. Genetic sequencing of P. vivax dhps (Pvdhps) from clinical isolates has shown several polymorphisms at the positions equivalent to those in the Pfdhps genes conferring sulfa drug resistance, suggesting a mechanism for sulfa drug resistance in P. vivax similar to that seen in P. falciparum. To characterize the role of polymorphisms in the PvDHPS in sulfa drug resistance, various mutants of recombinant PvHPPK-DHPS enzymes were expressed and characterized. Moreover, due to the lack of a continuous in vitro culture system for P. vivax parasites, a surrogate P. berghei model expressing Pvhppk-dhps genes was established to demonstrate the relationship between sequence polymorphisms and sulfa drug susceptibility and to test the activities of PvDHPS inhibitors on the transgenic parasites. Both enzyme activity and transgenic parasite growth were sensitive to sulfadoxine to different degrees, depending on the number of mutations that accumulated in DHPS. K i values and 50% effective doses were higher for mutant PvDHPS enzymes than the wild-type enzymes. Altogether, the study provides the first evidence of sulfa drug resistance at the molecular level in P. vivax. Furthermore, the enzyme inhibition assay and the in vivo screening system can be useful tools for screening new compounds for their activities against PvDHPS.

The Structural and Functional Basis for Recurring Sulfa Drug Resistance Mutations in Staphylococcus aureus Dihydropteroate Synthase

“…A survey of other organisms was conducted to determine which of these mutations is conserved across species (Table 2 ). Mutations equivalent to F17L were found in Neisseria meningitidis and Escherichia coli , and mutations equivalent to T51M were found in Plasmodium species, Pneumocystis carinii, Mycobacterium leprae , and Streptococcus pneumoniae (Dallas et al, 1992 ; Fermer et al, 1995 ; Lane et al, 1997 ; Maskell et al, 1997 ; Wang et al, 1997b ; Elena et al, 1998 ; Kazanjian et al, 1998 ; Mei et al, 1998 ; Kai et al, 1999 ; Williams et al, 2000 ; Pornthanakasem et al, 2016 ). A mutation homologous to E208K was also found in Plasmodium species but not in conjunction with any of the primary mutations (Pornthanakasem et al, 2016 ).…”

The prevalence of molecular markers of drug resistance in Plasmodium vivax from the border regions of Thailand in 2008 and 2014

“…Moreover, the double mutant allele ( G 383 G 553 ) displays reduced binding affinity between the PvDHPS domain and sulfadoxine in vitro and in vivo compared to the wild-type allele ( Imwong et al, 2005 ; Barnadas et al, 2011 ). However, it has also been reported that other mutations in the gene, including S382A, A383G and A553G, do not influence enzyme catalytic activity ( Pornthanakasem et al, 2016 ). We did not detect mutations at V585 in any isolates in this study.…”

Simultaneous detection of Plasmodium vivax dhfr, dhps, mdr1 and crt-o resistance-associated mutations in the Colombian Amazonian region

“…A 2015 evaluation in Colombia’s Córdoba department [ 17 ] stated that the P. vivax population was more genetically diverse than it had been thought. However, some genome regions had low diversity due to a selective sweep associated with the PvDHPS A383G allele [ 17 ] which, in turn, has been associated with sulfadoxine resistance [ 18 ]. The region surrounding PvDHFR did not have a loss of genetic diversity, as with PvDHPS; nevertheless, two alleles (S58R and S117N) [ 17 ] were reported to be associated with SP resistance [ 11 ].…”