Patients with positive HCV RNA were divided into three groups: groups of patients whose HCV RNA were only positive in serum, PBMCs and in serum and PBMC. Patients with positive HCV RNA in PBMCs were not always with positive HCV RNA in serum and vice versa. If we make the diagnosis of HCV infection by positive serum HCV RNA only, some of the patients were bound to miss detection.
Our results showed that some of the patients negative for HCV RNA in serum or PBMCs by FQ-RT-PCR turned out to be positive by nested RT-PCR, especially in PBMC detection. Detection rate of positive HCV RNA was higher in nested RT-PCR than that of FQ-RT-PCR confirming that nested RT-PCR was the more sensitive in detecting HCV RNA and the extent of HCV infection may be grossly underestimated by FQ-RT-PCR. It is strongly recommended to analyse for HCV RNA by nested RT-PCR in serum and especially in PBMCs whenever we encounter patients with suspected nonalcoholic steatohepatitis, cryptogenic cirrhosis or increased aminotransferase of unknown origin.
HCV is one of the major causes of hepatitis related to blood transfusion.10,11 A more disturbing concern, however, arises with regard to procedures used in blood transfusion. Blood donors with low HCV load in serum or PBMCs are always negative HCV for antibody and normal for aminotransferase, so HCV infection cannot be excluded only by assessing aminotransferase and HCV antibody. We should revaluate the methods of detection for transfused blood. To keep the blood transfusion safe, donors with occult HCV infected should be excluded efficiently.12-14 Occult HCV infected donors negative for HCV RNA in serum could be discovered positive HCV RNA in PBMCs easily by nested RT-PCR without liver biopsy. Therefore, it is necessary to detected HCV RNA in serum and PBMCs by nested RT-PCR anytime before we make the negative diagnosis of HCV infection.
Relapse following end of treatment of antiviral therapy is common. Patients “cured” after antiviral treatment with persistent viral response may have occult HCV infection in liver or PBMCs. HCV can finish replication within PBMCs.7 Thus HCV in PBMCs may be one of the causes of relapse after antiviral therapy. Perhaps nonclearance of HCV RNA in PBMCs is a predictor of persistent response to antiviral therapy and is a reference to formulate the duration of antiviral therapy in chronic hepatitis C.
In conclusion, nested RT-PCR is appropriate for diagnosis of HCV infection, and FQ-RT-PCR is fit for monitoring HCV load. Detection of HCV RNA in serum and PBMC can discover patients infected with HCV maximally. Detection of HCV RNA in PBMCs may be important to assess the virological response to interferon treatment and to predict relapse after antiviral therapy.
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