Quantification and duration of viraemia during hepatitis A infection as determined by real-time RT-PCR.

Human transmission studies and molecular techniques have provided evidence that transient viraemia occurs during infection with hepatitis A virus (HAV). However, the duration of its presence and levels during the phases of clinical disease and convalescence has not yet been well studied in human patients. Real-time RT-PCR techniques are increasingly used to quantify RNA viruses for diagnosis and/or research purposes. We have optimized a one-step RT-PCR that contains a dual-labelled fluorogenic probe to quantify the 5' noncoding region (5' NCR) of HAV. This method has a dynamic range (5-5 x 10(6) copies). The coefficient of regression of the standard curve was, on average 0.978. Intra-assay CVs% varied from 6.1% to 0.98%, and interassay CVs% from 6.46% to 2.1%. In the currently reported study 41 HAV IgM positive serum samples and 200 serum samples from healthy blood donors were tested by the quantitative RT-PCR method. The mean values on the first day of diagnosis found was 6.38 x 10(5) copies/mL. In a longitudinal study, viraemia persisted for an average of 60 days after clinical onset. These results show that viraemia in HAV infection lasts for many weeks.