Transcription-mediated amplification is more sensitive than conventional PCR-based assays for detecting residual serum HCV RNA at end of treatment

OBJECTIVE: In patients chronically infected with hepatitis C virus (HCV) un dergoing antiviral therapy, sustained virologic response is suggested by vi ral clearance by end of treatment (EOT). Viral clearance is defined by nond etection of serum HCV RNA, usually by qualitative PCR-based assays with lim its of detection ranging from 100 to 1000 copies/ml. However, some individu als relapse after achieving apparent viral clearance by EOT. These individu als may have low levels of viremia not detected by current PCR methods. The aim of this retrospective study was to determine whether the Bayer HCV RNA Qualitative Assay, which employs Transcription Mediated Amplification (TMA ) and detects 50 HCV RNA copies/ml, could detect residual serum HCV RNA in patients who achieved apparent viral clearance by EOT and subsequently rela psed. METHODS: Samples were obtained at EOT (wk 24 or 48) and follow-up (wk 24-26 posttreatment) from 97 patients treated for HCV (78 relapsing patients, 19 sustained responders). All samples in which HCV RNA was not detected by PC R were tested in a blinded manner for HCV RNA by the TMA-based assay. RESULTS: HCV RNA was detected by the TMA-based assay in 27 (34.6%) EOT and 76 (97.4%) follow-up samples from relapsing patients, but not in any of the EOT or follow-up samples from sustained responders. CONCLUSION: Residual serum HCV RNA was detected by the TMA-based assay in E OT samples from 34.6% of patients that had achieved apparent viral clearanc e by PCR. The detection of HCV RNA by the TMA-based assay could help redefi ne EOT response and assist in the antiviral management of HCV infection. (A m J Gastroenterol 2001;96:2968-2972. (C) 2001 by Am. Coll. of Gastroenterol ogy).