A new, rapid assay, based on a single-round, multiplex PCR, can be used to detect Plasmodium falciparum, P. vivax, P. malariae or P. ovale in human blood. The PCR, which targets the conserved 18S small-subunit RNA genes of the parasites, not only permits a malarial infection to be detected but also allows each Plasmodium species present to be identified, even in cases of mixed infection.

The titres (genome equivalents/ml) of three HBV preparations were determined by several laboratories using different NAT assays. This study enabled the establishment of an international standard, 97/746, for HBV DNA NAT assays.

Sample AA was accepted as the candidate standard and assigned a titre of 10(5) international units (IU)/ml. The International Standard consists of a batch of vials each containing 50,000 IU/vial. Preliminary studies indicated that the material is stable at +4 degrees C and +20 degrees C for up to 200 days.

No abstract

Background and Objectives: The aims of this study were the establishment of a WHO International standard for HCV RNA for nucleic acid amplification technology (NAT) assays and the determination of the HCV RNA content of the candidate standard. Materials and Methods: Twenty–two laboratories evaluated three candidate materials (two lyophilised, AA and BB, which were derived from the same source and one a liquid preparation, CC). All samples were HCV genotype 1 with a concentration of approximately 10⁵ genome equivalents/ml. The methods used included the Roche Amplicor assay (version 1), Chiron Quantiplex (bDNA) assay, Organon Teknika NASBA assay, Transcription Mediated assay and various in–house assays, using single or nested primers. Results: There was reasonable agreement between the overall mean NAT detectable units/ml obtained by the different assays except for some of the in–house assays using single primers which gave substantially lower estimates. These titres were 5.0 log₁₀ for samples AA and BB and 4.6 log₁₀ for sample CC. Conclusions: Sample AA was accepted as the candidate standard and assigned a titre of 10⁵ international units (IU)/ml. The International Standard consists of a batch of vials each containing 50,000 IU/vial. Preliminary studies indicated that the material is stable at +4°C and +20°C for up to 200 days.