title: Comparison of WHO Mark III and HRP II ELISA forin vitrosensitivity ofPlasmodium falciparum.
abstract: OBJECTIVE
  Antimalarial drug resistance is a serious challenge to malaria control worldwide. In vitro sensitivity assays provide an early indication of emerging drug resistance. In vitro susceptibility of field and culture adapted Plasmodium falciparum isolates to different antimalarials was compared using two Methods: World Health Organization (WHO) micro-test (MARK III) and histidine rich protein II (HRP II) based enzyme- linked immunosorbent assay (ELISA).
  
  
  METHODS
  In total, 50 P. falciparum isolates were collected from five states, viz. Chhattisgarh, Meghalaya, Mizoram, Tripura and Odisha of India during December 2011-September 2014. The isolates were revived and evaluated for their susceptibility to chloroquine (CQ), monodesethylamodiaquine (AQ), mefloquine (MQ), quinine (QN) and artemisinin (ART) using the WHO micro-test (Mark III) and HRP II ELISA. The data were analyzed using non- linear regression analysis.
  
  
  RESULTS
  The geometric mean (GM) IC50 values of different antimalarials for WHO Mark III assay were comparatively lower than HRP II ELISA assay. The GM IC50 value for CQ was 59.5 nM (95% confidence interval [CI]: 49.35-71.73 nM) and 78.34 nM (95% CI: 64.57-95.03 nM) for Mark III and HRP II ELISA, respectively. Similarly, the values of GM IC50 for AQ, MQ, QN and ART by Mark III and HRP II ELISA were 13.31, 7.07, 146.4, 0.43 nM and 22.02, 11.46, 258.7, 1.00 nM, respectively. On analyzing statistically, the results of both assays were comparable (R2 = 0.96, p < 0.001; mean log difference at IC50= 0.037).
  
  
  CONCLUSIONS
  The HRP II ELISA assay showed a reliable sensitivity in comparison to WHO Mark III micro-test complemented with distinguishing features such as high specificity, ease of performance, and notable consistency.
authors.affiliation: National Institute of Malaria Research (ICMR), New Delhi, India.
authors.forename: Supriya
authors.initials: S
authors.lastname: Sharma
authors.affiliation: National Institute of Malaria Research (ICMR), New Delhi, India.
authors.forename: Neelima
authors.initials: N
authors.lastname: Mishra
authors.affiliation: National Institute of Malaria Research (ICMR), New Delhi, India.
authors.forename: Neena
authors.initials: N
authors.lastname: Valecha
authors.affiliation: National Institute of Malaria Research (ICMR), New Delhi, India.
authors.forename: Anupkumar R
authors.initials: AR
authors.lastname: Anvikar
mesh_terms: D000953:Antigens, Protozoan / Q000032:analysis; D000962:Antimalarials / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D007194:India; D020128:Inhibitory Concentration 50; D021261:Parasitic Sensitivity Tests / Q000379:methods*; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000302:isolation & purification; D012680:Sensitivity and Specificity
chemical_list: D000953:Antigens, Protozoan; D000962:Antimalarials