V. Weich

Long-term evaluation of patients with sustained virologic remission by highly sensitive HCV RNA assays: no evidence for viral persistence.

The induction of a sustained virologic response (SVR) in hepatitis virus (HCV) infected patients, defined as undetectable serum HCV NA levels 6 months after stopping therapy, is believed to herald he determination of the chronic HCV infection.1,2 However, recent ndings suggest that residual HCV RNA can persist in PBMC, lymhatic or liver tissue3–5 indicating that minimal residual hepatitis viremia can escape standard HCV RNA assays.6 Now Fytili et al. eported in this Journal that, minimal residual HCV RNA can be etected in more than 20% of SVR patients when serum samples ere tested with a highly sensitive RealTime PCR assay (Abbott, 2000 RealTime PCR).7 To further substantiate these findings, we re-evaluated 160 erum samples of 145 SVR patients with two different highly senitive HCV RNA assays, the Abbott RealTime PCR (m2000rt) system nd the Siemens Versant TMA® assay. Two different RNA extraction ethods were applied for the RealTime PCR assay: the manual RNA xtraction method was used in 97 patients while the automated ersion was employed in 63 patients. Median time after EOT was .1 years (range: 0.5–12 y). By using the TMA assay, only one sample out of 160 was found to e HCV-RNA positive (0.6%). In contrast, in 10% (n = 16) of the SVR atients HCV RNA was detectable by the RealTime PCR. 14 out of hese 16 positive samples have been treated by the manual extracion method (14.5% of those analysed manually, 9% of all), whereas CV RNA could be detected only in 2 out of 63 patients (3.2%, 1.4% of ll) when the fully automated version of the assay was applied. All ut one of the HCV RNA positive samples had levels below the limit f quantification of the assay (i.e. <12 IU/mL) see Fig. 1. But most mportantly, in none of the patient the positive HCV RNA result ould be confirmed by the TMA assay or vice versa. These findings ould be also confirmed by testing a second serum sample from a ifferent time point in 8 out of the 16 HCV RNA positive patients. oth assays, the TMA and the fully automated RealTime PCR test ave negative results. Thus our study contradicts Fytili’s conclusion and rather indiates that positive HCV RNA signals detectable by RealTime PCR re due to either unspecific amplification or contamination. This nterpretation is strengthens by our finding that the ratio of HCV NA positive samples by real time PCR was significantly higher hen using the manual extraction (14.5%) as compared to the fully utomated system (3%). We argue that most probably false posi-