title: Frequent hepatitis C virus superinfection in injection drug users.
abstract: The frequency of hepatitis C virus (HCV) superinfection with a divergent viral strain was determined in a cohort of recently infected young injection drug users (IDUs) with an HCV incidence rate of 25%. HCV was amplified, by use of polymerase chain reaction (PCR), from plasma samples collected from 25 HCV-infected individuals over an average period of 12 months, and their viral sequences were compared. Phylogenetic analysis identified 5 IDUs with superinfection (20%) occurring after seroconversion: 2 IDUs were superinfected with different HCV genotypes, and 3 were superinfected with divergent strains of the same genotype. The superinfecting strains were not detected as minority variants (<0.5%) in the initial plasma HCV quasi species. Extensive measures were taken to exclude PCR contamination and mix-up of samples, and superinfection results were concordant at 2 HCV genetic loci. HCV superinfection in IDUs, both intra- and intergenotype, is therefore a frequent event, with an incidence rate similar to that of de novo infections. These results suggest that no cross-protecting immunity develops during the first year of chronic infection with HCV.
authors.affiliation: Blood Systems Research Institute, University of California, San Francisco, Califronia, USA.
authors.forename: Belinda L
authors.initials: BL
authors.lastname: Herring
authors.forename: Kimberly
authors.initials: K
authors.lastname: Page-Shafer
authors.forename: Leslie H
authors.initials: LH
authors.lastname: Tobler
authors.forename: Eric L
authors.initials: EL
authors.lastname: Delwart
mesh_terms: D000328:Adult; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics / Q000302:isolation & purification; D006526:Hepatitis C / Q000453:epidemiology* / Q000821:virology; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D012307:Risk Factors; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000453:epidemiology*; D015163:Superinfection / Q000453:epidemiology* / Q000821:virology