THE LIGASE CHAIN-REACTION IN DNA-BASED DIAGNOSIS

Clinical specimens containing a suspected pathogen often have too litt le of the pathogen's DNA to be detected directly. It is generally nece ssary to first amplify die DNA and then to detect the amplification pr oducts. An amplification technique called the ligase chain reaction (L CR) is described, which in conjunction with an automated, non-radioact ive readout format allows less than 10 molecules of target DNA to be d etected. A prototype HIV assay and two prototype Chlamydia assays have sensitivities and specificities equivalent to PCR.