We have developed an automated multiplex system for simultaneously screening hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus type 1 (HIV-1) in blood donations. The assay, designated AMPLINAT MPX HBV/HCV/HIV-1 Test (AMPLINAT MPX), consists of virus extraction and target sequence-specific probe capture on specimen preparation workstation GT-X (Roche Diagnostics K.K., Tokyo, Japan) and amplification and detection by TaqMan PCR on the ABI PRISM 7700 Analyzer (PerkinElmer Applied Biosystems, Foster City, Calif.). An internal control (IC) is incorporated in the assay to monitor the extraction, target amplification, and detection processes. The assay yields qualitative results without discrimination of the three targets. Detection limits (95% confidence interval) are 22 to 60 copies/ml for HBV, 61 to 112 IU/ml for HCV, and 33 to 66 copies/ml for HIV-1, using a specimen input volume of 0.2 ml. The AMPLINAT MPX assay detects a broad range of genotypes or subtypes for all three viruses and has a specificity of 99.6% for all three viruses with seronegative specimens. In an evaluation of seroconversion panels, the AMPLINAT MPX assay detects HBV infection an average of 24 days before the detection of HBsAg by enzyme immunoassay. HCV RNA was detected an average of 31 days before HCV antibody. HIV-1 RNA was detected an average of 14 days before HIV-1 antibody and an average of 9 days before p24 antigen. The Japanese Red Cross has been evaluating the AMPLINAT MPX system since October 1999. The clinical performance indicates that the AMPLINAT MPX system is robust, sensitive, and reproducible, with a high percentage of valid assay runs (96.8%), a low false-positive rate (0.34%), and a low IC failure rate (0.24%).

A preclinical evaluation of a qualitative assay for the detection of hepatitis C virus (HCV) RNA by transcription-mediated amplification (TMA) was conducted according to the guidelines of the National Committee for Clinical Laboratory Standards and the U.S. Food and Drug Administration. Our results showed that this assay, HCV TMA, detected 95% of samples with HCV RNA concentrations of 5.3 IU/ml and 29 copies/ml. HCV TMA showed an overall specificity of 99.6% and was highly reproducible, detecting 99.3% of samples with HCV RNA concentrations of 50 copies/ml across seven different lots of reagents. Experiments with clinical samples showed that HCV TMA detected all HCV genotypes with similar efficiencies, detecting >95% of samples at 50 HCV RNA copies/ml from patients infected with HCV genotypes 1a, 2b, 3a, 4a, 5a, and 6a. In experiments with RNA transcripts, HCV TMA detected >96.6% of transcripts derived from HCV genotypes 1a, 1b, 2a, 2c, 3a, 4a, 5a, and 6a at 50 HCV RNA copies/ml. Detection of transcripts derived from HCV genotype 2b was slightly lower (88.4%) at 50 copies/ml but was 97.0% at 75 copies/ml. In addition, HCV TMA exhibited robust performance in detecting HCV RNA in samples subjected to various conditions commonly encountered in a clinical laboratory, including long-term storage, multiple freeze-thaw cycles, different collection tubes, and the presence of endogenous substances, commonly prescribed drugs, or other microorganisms and viruses. With its high sensitivity, specificity, reproducibility, and equivalent genotype reactivity, HCV TMA may provide an attractive alternative for routine qualitative HCV RNA testing in clinical laboratories.As global population estimates reach 170 million infected with the hepatitis C virus (HCV) (23), there has never been a more pressing need for sensitive, precise tests for active infections. Although enzyme immunoassays (EIA) followed by confirmatory immunoblot assays have been traditionally used for screening and testing of blood, neither assay can differentiate between active and resolved infection. Qualitative and quantitative HCV RNA testing as well as HCV antigen detection methods can identify active infection, but with quantitative tests usually being 1 to 2 logs less sensitive than qualitative tests and with the limited availability of antigen methods, qualitative HCV RNA testing is the method of choice for confirming active infection and assessing viral clearance in response to therapy (8).Qualitative HCV RNA assays currently used are based on PCR technology and include the AMPLICOR HCV 2.0,

No abstract