Find in Library

<p>Abstract</p> <p>Background</p> <p>In order to harmonize results for the detection and quantification of <it>Plasmodium falciparum </it>DNA by nucleic acid amplification technique (NAT)-based assays, a World Health Organization (WHO) collaborative study was performed, evaluating a series of candidate standard preparations.</p> <p>Methods</p> <p>Fourteen laboratories from 10 different countries participated in the collaborative study. Four candidate preparations based upon blood samples parasitaemic for <it>P. falciparum </it>were evaluated in the study. Sample AA was lyophilized, whilst samples BB, CC and DD were liquid/frozen preparations. The candidate standards were tested by each laboratory at a range of dilutions in four independent assays, using both qualitative and quantitative NAT-based assays. The results were collated and analysed statistically.</p> <p>Results</p> <p>Twenty sets of data were returned from the participating laboratories and used to determine the mean <it>P. falciparum </it>DNA content for each sample. The mean log₁₀"equivalents"/ml were 8.51 for sample AA, 8.45 for sample BB, 8.35 for sample CC, and 5.51 for sample DD. The freeze-dried preparation AA, was examined by accelerated thermal degradation studies and found to be highly stable.</p> <p>Conclusion</p> <p>On the basis of the collaborative study, the freeze-dried material, AA (NIBSC code No. 04/176) was established as the 1^stWHO International Standard for <it>P. falciparum </it>DNA NAT-based assays and has been assigned a potency of 10⁹International Units (IU) per ml. Each vial contains 5 × 10⁸IU, equivalent to 0.5 ml of material after reconstitution.</p>