@article{Pua_Abu Bakar_Nik Kamarudin_Ghazali_Khairul Mohd Fadzli Mustaffa_2020, title={Long cryopreserved lab-adapted Plasmodium falciparum increases resistance to chloroquine but not its susceptibility}, volume={4}, url={https://biomescientia.com/index.php/lsmb/article/view/66}, DOI={10.28916/lsmb.4.9.2020.66}, abstractNote={<p><strong>Introduction: </strong><em>Plasmodium falciparum</em> (<em>P. falciparum</em>) is a deadly protozoan that is accountable for malaria and chloroquine was the first-line antimalarial drug before its withdrawal and replaced by artemisinin. To date, several studies showed that <em>P. falciparum</em> had regained its sensitivity towards chloroquine after its withdrawal for decades. By understanding the basic principle and mechanism of chloroquine resistance in <em>P. falciparum</em>, at the molecular level, it would be valuable prior to the re-introduction of chloroquine as a first-line anti-malarial drug for malaria treatment. Thus, this study was conducted to determine the chloroquine resistance level of long preserved lab-adapted <em>P. falciparum </em>strain. <strong>Methodology:</strong><em><strong> </strong></em>By using 14 years (2006-2020) cryopreserved chloroquine-sensitive (3D7) and chloroquine-resistant (W2) lab-adapted <em>P. falciparum</em> strains, the strains were subjected to continuous culture for three months before <em>in vitro</em> drug susceptibility assay and single nucleotide polymorphisms (SNP) analysis on Pfcrt and Pfmdr-1 gene for both strains. <strong>Results:<em> </em></strong>This study shows the IC<sub>50</sub> chloroquine of lab-adapted <em>P. falciparum</em> 3D7 and W2 strains were at 32.98 nM and 691.21 nM, respectively and both strains showed 3-fold higher IC<sub>50</sub> when compared to their susceptibility before cryopreserved (3D7; 13.84nM and W2; 208.27 nM). The SNPs result showed a consistent amino acid substitution at position 76 (K to T) on PfCRT and 86 (N to Y) in Pfmdr-1 gene which concordance with other studies before preservation. <strong>Conclusion: </strong>Thus, this study shows that long cryopreserved of lab-adapted <em>P. falciparum</em> increases the chloroquine resistance level but not exhibited any change in susceptibility.</p>}, number={9}, journal={Life Sciences, Medicine and Biomedicine}, author={Pua, Jing Yit and Abu Bakar, Nurhidanatasha and Nik Kamarudin, Nik Abdul Aziz and Ghazali, Siti Zulaiha and Khairul Mohd Fadzli Mustaffa}, year={2020}, month={Nov.} }