Frequency of very low HCV viremia detected by a highly sensitive HCV-RNA assay

Only limited data is available on the frequency and clinical significance of very low hepatitis C viremia (<600 IU/ml) determined by novel sensitive methods for HCV quantification.

We evaluated the new Abbott m2000 RealTime PCR assay in 3213 consecutive anti-HCV-positive sera as well as in 50 HCV-recovered patients with sustained virological response to standard antiviral therapy.

The assay showed a linear range between 10(1) IU/ml and 10(7) IU/ml for HCV genotypes 1-6. An HCV viremia below 600 IU/ml was detected more often with the m2000 RealTime PCR assay than with the Cobas Amplicor assay in viremic sera (7.1% versus 1.8%). Seventy-seven cases with HCV levels below 100 IU/ml not related to ongoing antiviral therapy were identified. An HCV-RNA of less than 12 IU/ml was found in nine of the 50 SVR patients. Two patients had a viral load of 34 IU/ml and 84 IU/ml, respectively, one of those showed persistently elevated ALT levels over a period of 5 years after the end of antiviral treatment.

An HCV viremia below 600 IU/ml can be detected in almost every 40th anti-HCV-positive sera using real-time PCR based assays. Low persisting HCV-RNA in patients after antiviral therapy may be associated with mild liver inflammation in single cases.