Strategy for the maximization of clinically relevant information from hepatitis C virus, RT-PCR quantification

Background: The increasing clinical application of viral load assays for mo nitoring viral infections has been an incentive for the development of stan dardized tests for the hepatitis C virus. Objective : To develop a simple m odel for the prediction of baseline viral load in individuals infected with the hepatitis C virus. Methodology: Viral load quantification of each pati ent's first sample was assessed by RT-PCR-ELISA using the Roche MONITOR ass ay in triplicate. Genotype of the infecting virus was identified by reverse line probe hybridization. using amplicons resulting from the qualitative H CV Roche AMPLICOR assay. Results: Retrospective evaluation of first quantit ative values suggested that 82.4% (n = 168/204) of individuals had a viral load between 4.3 and 6.7 log(10) viral copies per mi. A few patients (3.4%; n = 7/204) have a serum viremia less than the lower limit of the linear ra nge of the RT-PCR assay. Subsequent, prospective evaluation of hepatitis C viral load of all new patients: using a model based on the dynamic range of viral load in the retrospective group correctly predicted the dynamic rang e in 75.9% (n = 33/54). Conclusion: The dynamic range of hepatitis C viremi a extends beyond the linear range of the Roche MONITOR assay. Accurate dete rmination of serum viremia is substantially improved by dilution of specime ns prior to quantification. (C) 2001 Elsevier Science B.V. All rights reser ved.