PLoS ONE (Jan 2012)

Prevalence and follow-up of occult HCV infection in an Italian population free of clinically detectable infectious liver disease.

  • Laura De Marco,
  • Paola Manzini,
  • Morena Trevisan,
  • Anna Gillio-Tos,
  • Franca Danielle,
  • Cinzia Balloco,
  • Alessandra Pizzi,
  • Eleonora De Filippo,
  • Sergio D'Antico,
  • Beatrice Violante,
  • Adriano Valfrè,
  • Franco Curti,
  • Franco Merletti,
  • Lorenzo Richiardi

DOI
https://doi.org/10.1371/journal.pone.0043541
Journal volume & issue
Vol. 7, no. 8
p. e43541

Abstract

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BACKGROUND: Occult hepatitis C virus infection (OCI) is a recently described phenomenon characterized by undetectable levels of HCV-RNA in serum/plasma by current laboratory assays, with identifiable levels in peripheral blood mononuclear cells (PBMCs) and/or liver tissue by molecular tests with enhanced sensitivity. Previous results from our group showed an OCI prevalence of 3.3% in a population unselected for hepatic disease. The present study aimed to evaluate OCI prevalence in a larger cohort of infectious liver disease-free (ILDF) subjects. Clinical follow-up of OCI subjects was performed to investigate the natural history of the infection. METHODS AND FINDINGS: 439 subjects referred to a Turin Blood Bank for phlebotomy therapy were recruited. They included 314 ILDF subjects, 40 HCV-positive subjects and 85 HBV-positive subjects, of whom 7 were active HBV carriers. Six subjects (4/314 ILDF subjects [1.27%] and 2/7 active HBV carriers [28%]) were positive for HCV-RNA in PBMCs, but negative for serological and virological markers of HCV, indicating OCI. HCV genotypes were determined in the PBMCs of 3/6 OCI subjects two had type 1b; the other had type 2a/2c. OCI subjects were followed up for at least 2 years. After 12 months only one OCI persisted, showing a low HCV viral load (3.73×10(1) UI/ml). By the end of follow-up all OCI subjects were negative for HCV. No seroconversion, alteration of liver enzyme levels, or reduction of liver synthesis occurred during follow-up. CONCLUSIONS: This study demonstrated the existence of OCI in ILDF subjects, and suggested a high OCI prevalence among active HBV carriers. Follow-up suggested that OCI could be transient, with a trend toward the decrease of HCV viral load to levels undetectable by conventional methods after 12-18 months. Confirmation studies with a longer follow-up period are needed for identification of the OCI clearance or recurrence rates, and to characterize the viruses involved.