Genetic Basis of Resistance to Pure Artemisinin and Artemisia Annua Extracts in Plasmodium Falciparum
Artemisinin-based combination therapy has been a vital tool in malaria control and elimination programmes.
However, artemisinin resistant P. falciparum parasites have emerged in Southeast Asia, posing a major threat to the
effectiveness of ACT. Resistance results in prolonged parasite clearance in vivo and enhanced survival of ring-stage parasites
in vitro. Therefore, understanding the genetic basis of resistance would be critical to the success treatment and intervention
strategies. This study aimed at identifying single nucleotide polymorphisms associated with artemisinin and Artemisia annua
resistance. Genetic analysis was done on P. falciparum lines W2 and D6, previously selected under pure artemisinin and
Artemisia annua extracts. Genomic DNA was extracted using QIAamp blood mini kit. Libraries were sequenced using
Illumina Miseq platform with 151bp paired-end reads. Sequencing read data from each sample was mapped against
P.falciparum reference sequence V3.1. One non-synonymous (NS) mutation K189T was identified in the
Plasmodium/Apicomplexa-specific domain of K13 gene. The Pfmdr1 mutation N86Y was detected in W2 parasite exposed to
pure artemisinin at IC50 equivalents and importantly the Pfcrt CQ sensitive CVMNK genotype was retained in 80% samples.
The study also identified one background mutation in Pfcrt gene at codon 356 (I356T) in W2 parasites exposed to artemisinin
at IC50 equivalents. In conclusion, K13 K189T mutation have not been associated with delayed parasite clearance or in vitro
artemisinin resistance. Pfmdr1 may putatively play a role in artemisinin resistance.
Key words- Artemisinin-resistance, K13 gene, malaria, Plasmodium falciparum