Predictive value of the detection of viral RNA in lymphocytes of patients having a chronic hepatitis C under interferon alpha therapy and comparison with other virological markers 1-Laboratory of bacteriology-virology; hospital Avicenne, UFR Bobigny, 2-Laboratory of microbiology; hospital of Versailles, 3-Service of Hepatogastroenterology; hospital Avicenne, UFR Bobigny, 4-Service of medicine A; hospital of Versailles, Franc EU