[Discovery of a chronic HVC infection without seroconversion in a blood donor in France during 28 months]

The HCV-RNA screening technique developed by the French Fractionation and Biotechnology Laboratory singled out in March 1998 a case of positive HCV-RNA viremia in a blood donor without any anti-HCV antibody. That donor was a 46-year-old woman who had made 54 donations of blood products from 1988 to 1997. She had no history of blood transfusion, no history of hepatitis and no life-style risk factor. Clinical examination was normal. Liver tests (serum alanine amino transferases, gamma glutamyl transpeptidase , alkaline phosphatase, bilirubin , prothrombin and albumin) were normal. Total blood count was normal. Lymphocyte count was normal as well as in vitro functional analysis of lymphocytes (stimulation with different antigens). All screening HCV Elisa tests and immunoblot System available on the French market were unable to detect anti-HCV antibodies. Quantification of serum HCV-RNA (Amplicor Monitor Roche) showed 294,000 copies/mL and HCV genotype 1b determination was performed using Innolipa assay. Further examination of the HCV genotype by direct sequencing of the PCR product showed a classical 1b genotype sequence. The hemovigilance inquiry identified 25 labile products distributed since 1988. Analyzing the records of the recipients that have so far been traced and identified revealed three periods: 1997 to 1995: three recipients were found to be positive for anti-HCV antibodies; two are now cured of hepatitis C. In one recipient, direct sequencing after specific PCR of the hypervariable region coding for the envelope domain showed 100% homology with the donor; 1993 to 1990: four recipients were identified and traced without contamination; in 1988: three of four blood product recipients were anti-HCV negative without HCV-RNA viremia. The forth carried anti-HCV antibodies and genotype 1b HCV-RNA but had a history of multiple surgery. Alter et al. [4] and Bush et al. [5] have previously suggested the possibility of a chronic, immunologically silent state of infection. The case described herein, is the first evidence for this hypothesis. Indeed, the donor has not yet seroconverted 28 months after viremia was discovered. This blood donor was identified by HCV-RNA screening of plasma products. The identification of the same sequence in a recipient of blood from this donor clearly establishes the transmission of the virus by transfusion. The prevalence of such cases of infectious silent chronic HCV carriers has to be determined and the mechanisms responsible for the absence of antibody production need to be clarified.