title: High rate of spontaneous negativity for hepatitis C virus RNA after establishment of chronic infection in Alaska Natives.
abstract: BACKGROUND
  Hepatitis C virus (HCV) leads to chronic infection in 70%-85% of exposed patients. Spontaneous clearance of the virus after chronic infection is believed to occur rarely.
  
  
  METHODS
  Alaska Natives who tested positive for HCV antibodies were enrolled in a prospective study that began in 1994 and were followed up on a regular basis. Individuals who tested positive for HCV RNA on 3 separate dates, each of which were at least 1 year apart, were included. Being negative for the virus was defined as having at least 1 negative HCV RNA test result after chronic viremia had been established.
  
  
  RESULTS
  Of the 815 patients enrolled in the cohort, 139 met entry criteria and were observed for a mean period of 7.0 years. Eleven (8%) of the persons had at least 1 test in which HCV RNA was undetectable; 7 were classified as having either possible or probable clearance of the virus, corresponding to an annualized clearance rate of 0.74% per person-year (95% CI, 0.30%-1.53%). Of 9 patients who underwent subsequent HCV RNA testing, 5 (56%) had negative test results. A low HCV RNA level was significantly associated with spontaneous nondetectability of HCV RNA.
  
  
  CONCLUSIONS
  Spontaneous HCV RNA negativity during chronic HCV infection is a surprisingly frequent event and is associated with low HCV RNA titers. Knowledge of immunologic determinants of clearance may open up avenues of novel therapy.
authors.affiliation: Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA. jdscott@u.washington.edu
authors.forename: John D
authors.initials: JD
authors.lastname: Scott
authors.forename: Brian J
authors.initials: BJ
authors.lastname: McMahon
authors.forename: Dana
authors.initials: D
authors.lastname: Bruden
authors.forename: Daniel
authors.initials: D
authors.lastname: Sullivan
authors.forename: Chriss
authors.initials: C
authors.lastname: Homan
authors.forename: Carol
authors.initials: C
authors.lastname: Christensen
authors.forename: David R
authors.initials: DR
authors.lastname: Gretch
mesh_terms: D000328:Adult; D000367:Age Factors; D000413:Alaska; D005260:Female; D016174:Hepacivirus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D018937:Hepatitis C Antibodies / Q000097:blood; D019698:Hepatitis C, Chronic / Q000276:immunology / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000097:blood*
chemical_list: D018937:Hepatitis C Antibodies; D012367:RNA, Viral