We evaluated a new real-time PCR-based prototype assay for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae developed by Abbott Molecular Inc. This assay is designed to be performed on an Abbott m2000 real-time instrument system, which consists of an m2000sp instrument for sample preparation and an m2000rt instrument for real-time PCR amplification and detection. The limit of detection of this prototype assay was determined to be 20 copies of target DNA for both C. trachomatis and N. gonorrhoeae, using serially diluted linearized plasmids. No cross-reactivity could be detected when 55 nongonococcal Neisseria isolates and 3 non-C. trachomatis Chlamydia isolates were tested at 1 million genome equivalents per reaction. Concordance with the Roche Amplicor, BDProbeTec ET, and Gen-Probe APTIMA Combo 2 tests was assessed using unlinked/deidentified surplus clinical specimens previously analyzed with these tests. For C. trachomatis, concordance for positive results ranged from 93.7% to 100%, while concordance for negative results ranged from 98.2% to 100%. For N. gonorrhoeae, concordance for positive and negative results ranged from 91.4% to 100% and 99.3% to 100%, respectively. A workflow analysis of the prototype assay was conducted to obtain information on throughput under laboratory conditions. At 48 samples/run, the time to first result for both C. trachomatis and N. gonorrhoeae was 4.5 h. A total of 135 patient specimens could be analyzed in 8.9 h, with 75 min of hands-on time. This study demonstrated the technical and clinical feasibility of the new Abbott real-time PCR C. trachomatis/N. gonorrhoeae assay.

Molecular beacons are single-stranded, fluorophore-labeled nucleic acid probes that are capable of generating a fluorescent signal in the presence of target, but are dark in the absence of target. Molecular beacons allow multiplex detection of PCR products in real time in a homogeneous assay format. Real time detection is inherently quantitative and affords a greater dynamic range than end-point detection methods. Reactions in a homogeneous assay format are sealed before amplification takes place, providing improved contamination control. A single cycler/reader instrument, coupled with automated sample preparation, results in higher throughput and greater ease of use. A multiplex qualitative assay that detects Chlamydia trachomatis and Neisseria gonorrhoeae, along with an internal control, has been developed. High specificity is achieved through careful selection of primers, probes and assay conditions. Quantitative HIV, HCV, and HBV viral load assays, with sensitivities of 50 copies/ml, 20 IU/ml, and 50 copies/ml, respectively, are achievable. The viral load assays are designed to quantitate all subtype and genotype specimens equivalently. A molecular beacon assay has been designed to detect a single nucleotide polymorphism in the beta2 adrenergic receptor gene.

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The factor V Leiden mutation, a G→A transition at position 1691 in exon 10 of the gene that codes for factor V, produces an Arg506Gln substitution and is the most common genetic risk factor for venous thrombosis. We have developed a rapid, sensitive, and specific method to detect the factor V Leiden mutation in genomic DNA from whole blood by PCR amplification and microparticle enzyme immunoassay detection using the Abbott LCx instrument. We compared this automated method with the standard procedure using restriction endonuclease digestion of PCR products followed by gel electrophoresis in blinded experiments. In 130 patients (from Veterans Affairs medical centers) with deep venous thromboses, including 24 heterozygotes with the factor V Leiden mutation, there was complete agreement between the two methods. The assay was also able to distinguish heterozygotes from homozygotes. This method, which carries a low potential for cross-contamination of samples, should be a useful routine test for the factor V Leiden mutation in clinical laboratories with sufficient demand for molecular diagnostic assays using the LCx instrument.