Grigg MJ; Barber BE; Marfurt J; Imwong M; William T; Bird E; Piera KA; Aziz A; Boonyuen U; Drakeley CJ; Cox J; White NJ; Cheng Q; Yeo TW; Auburn S; Anstey NM

Author(s)

Grigg MJ

Barber BE

Marfurt J

Imwong M

William T

Bird E

Piera KA

Aziz A

Boonyuen U

Drakeley CJ

Cox J

White NJ

Cheng Q

Yeo TW

Auburn S

Anstey NM

Publication Date

2016

Abstract

Malaria caused by zoonotic Plasmodium knowlesi is an emerging threat in Eastern Malaysia. Despite demonstrated vector competency, it is unknown whether human-to-human (H-H) transmission is occurring naturally. We sought evidence of drug selection pressure from the antimalarial sulfadoxine-pyrimethamine (SP) as a potential marker of H-H transmission. The P. knowlesi dihdyrofolate-reductase (pkdhfr) gene was sequenced from 449 P. knowlesi malaria cases from Sabah (Malaysian Borneo) and genotypes evaluated for association with clinical and epidemiological factors. Homology modelling using the pvdhfr template was used to assess the effect of pkdhfr mutations on the pyrimethamine binding pocket. Fourteen non-synonymous mutations were detected, with the most common being at codon T91P (10.2%) and R34L (10.0%), resulting in 21 different genotypes, including the wild-type, 14 single mutants, and six double mutants. One third of the P. knowlesi infections were with pkdhfr mutants; 145 (32%) patients had single mutants and 14 (3%) had double-mutants. In contrast, among the 47 P. falciparum isolates sequenced, three pfdhfr genotypes were found, with the double mutant 108N+59R being fixed and the triple mutants 108N+59R+51I and 108N+59R+164L occurring with frequencies of 4% and 8%, respectively. Two non-random spatio-temporal clusters were identified with pkdhfr genotypes. There was no association between pkdhfr mutations and hyperparasitaemia or malaria severity, both hypothesized to be indicators of H-H transmission. The orthologous loci associated with resistance in P. falciparum were not mutated in pkdhfr. Subsequent homology modelling of pkdhfr revealed gene loci 13, 53, 120, and 173 as being critical for pyrimethamine binding, however, there were no mutations at these sites among the 449 P. knowlesi isolates. Although moderate diversity was observed in pkdhfr in Sabah, there was no evidence this reflected selective antifolate drug pressure in humans.

Citation

PloS one 2016; 11(3): e0149519

Pubmed ID

https://pubmed.ncbi.nlm.nih.gov/26930493/?otool=iaurydwlib

Link

https://hdl.handle.net/10137/5377

MESH subject

Adolescent

Adult

Aged

Aged, 80 and over

Antimalarials

Child

Child, Preschool

Drug Resistance

Female

Folic Acid Antagonists

Humans

Infant

Malaria

Malaysia

Male

Middle Aged

Molecular Docking Simulation

Plasmodium knowlesi

Pyrimethamine

Tetrahydrofolate Dehydrogenase

Young Adult

Title

Dihydrofolate-Reductase Mutations in Plasmodium knowlesi Appear Unrelated to Selective Drug Pressure from Putative Human-To-Human Transmission in Sabah, Malaysia.

Type of document

Journal Article

Entity Type

Publication

Author(s)	Grigg MJ Barber BE Marfurt J Imwong M William T Bird E Piera KA Aziz A Boonyuen U Drakeley CJ Cox J White NJ Cheng Q Yeo TW Auburn S Anstey NM
Publication Date	2016
Abstract	Malaria caused by zoonotic Plasmodium knowlesi is an emerging threat in Eastern Malaysia. Despite demonstrated vector competency, it is unknown whether human-to-human (H-H) transmission is occurring naturally. We sought evidence of drug selection pressure from the antimalarial sulfadoxine-pyrimethamine (SP) as a potential marker of H-H transmission. The P. knowlesi dihdyrofolate-reductase (pkdhfr) gene was sequenced from 449 P. knowlesi malaria cases from Sabah (Malaysian Borneo) and genotypes evaluated for association with clinical and epidemiological factors. Homology modelling using the pvdhfr template was used to assess the effect of pkdhfr mutations on the pyrimethamine binding pocket. Fourteen non-synonymous mutations were detected, with the most common being at codon T91P (10.2%) and R34L (10.0%), resulting in 21 different genotypes, including the wild-type, 14 single mutants, and six double mutants. One third of the P. knowlesi infections were with pkdhfr mutants; 145 (32%) patients had single mutants and 14 (3%) had double-mutants. In contrast, among the 47 P. falciparum isolates sequenced, three pfdhfr genotypes were found, with the double mutant 108N+59R being fixed and the triple mutants 108N+59R+51I and 108N+59R+164L occurring with frequencies of 4% and 8%, respectively. Two non-random spatio-temporal clusters were identified with pkdhfr genotypes. There was no association between pkdhfr mutations and hyperparasitaemia or malaria severity, both hypothesized to be indicators of H-H transmission. The orthologous loci associated with resistance in P. falciparum were not mutated in pkdhfr. Subsequent homology modelling of pkdhfr revealed gene loci 13, 53, 120, and 173 as being critical for pyrimethamine binding, however, there were no mutations at these sites among the 449 P. knowlesi isolates. Although moderate diversity was observed in pkdhfr in Sabah, there was no evidence this reflected selective antifolate drug pressure in humans.
Citation	PloS one 2016; 11(3): e0149519
Pubmed ID	https://pubmed.ncbi.nlm.nih.gov/26930493/?otool=iaurydwlib
Link	https://hdl.handle.net/10137/5377
MESH subject	Adolescent Adult Aged Aged, 80 and over Antimalarials Child Child, Preschool Drug Resistance Female Folic Acid Antagonists Humans Infant Malaria Malaysia Male Middle Aged Molecular Docking Simulation Plasmodium knowlesi Pyrimethamine Tetrahydrofolate Dehydrogenase Young Adult
Title	Dihydrofolate-Reductase Mutations in Plasmodium knowlesi Appear Unrelated to Selective Drug Pressure from Putative Human-To-Human Transmission in Sabah, Malaysia.
Type of document	Journal Article
Entity Type	Publication

Dihydrofolate-Reductase Mutations in Plasmodium knowlesi Appear Unrelated to Selective Drug Pressure from Putative Human-To-Human Transmission in Sabah, Malaysia.

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