Our research laboratories have been performing HCV RNA detection in patients' sera by the PCR technology, using both the in-house method 18 and recently, the Roche Amplicor TM PCR assay. Samples that were HCV RNA-positive by PCR amplification of the 5' noncoding region were processed for amplification of core region sequences. One hundred and nineteen specimens exhibited positive amplification of the core region. Figures 1 and 2 show representative positive and negative samples of amplification of the 5' noncoding region and core region, respectively. These samples may require genotyping by using other genomic regions.
P is a positive serum control.
N1 and N2 are negative controls of serum from a normal blood donor and reagent control, respectively. Of these, the direct sequencing is the most precise method. Aside from being cumbersome, it may not be readily available to many laboratories. We used direct sequencing of PCR-amplified product in the core region of HCV genome, since it has previously been successfully used. Although the sample number was not known, the results of these studies collectively indicated that genotype 4 is the most prevalent.