The clinical utility of viral quantitation using molecular methods

Background: The quantitation of viral nucleic acids in biological fluids has become increasingly desirable over the past several years. To this end, a number of quantitative molecular procedures have been developed. Objectives: The objective was to review the current literature on the molecular techniques used in the quantitation of viral nucleic acids and to assess the appropriateness of these methods for clinical use. Results: Assays involving both target and signal amplification are now available for the accurate and precise quantitation of viral burden in infected patients. These methods include quantitative polymerase chain reaction (PCR), branched chain signal amplification (bDNA), nucleic acid sequence-based amplification (NASBA) and the SHARP signal and hybrid capture systems. Our understanding of the natural history and pathogenesis of viruses such as the human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), cytomegalovirus (CMV) and Epstein–Barr virus (EBV) may be greatly facilitated by accurate determinations of viral and infected cell burden. Quantitation of viral load in infected individuals may also be useful to assess disease progression, monitor the efficacy of therapy and to predict treatment failure and the emergence of drug-resistant viruses. Conclusion: Precise, accurate and reproducible quantitation of viral load is now feasible. Molecular assays for viral quantitation should have a considerable impact on medical research and clinical care.