title: Higher risk of incident hepatitis C virus coinfection among men who have sex with men, in whom the HIV genetic bottleneck at transmission was wide.
abstract: BACKGROUND
  High-risk sexual behaviors have been suggested as drivers of the recent dramatic increase of sexually transmitted hepatitis C virus (HCV) among human immunodeficiency virus (HIV)-infected men who have sex with men (MSM).
  
  
  METHODS
  We assessed the association between the genetic bottleneck of HIV at transmission and the prevalence and incidence of HCV coinfection in HIV-infected MSM from the Swiss HIV Cohort Study (SHCS). As a proxy for the width of the transmission bottleneck, we used the fraction of ambiguous nucleotides detected by genotypic resistance tests sampled during early HIV infection. We defined a broad bottleneck as a fraction of ambiguous nucleotides exceeding a previously established threshold (0.5%).
  
  
  RESULTS
  From the SHCS, we identified 671 MSM with available results of HCV serologic tests and with an HIV genotypic resistance test performed during early HIV infection. Of those, 161 (24.0%) exhibited a broad HIV transmission bottleneck, 38 (5.7%) had at least 1 positive HCV test result, and 26 (3.9%) had an incident HCV infection. Individuals with broad HIV transmission bottlenecks exhibited a 2-fold higher odds of having ever experienced an HCV coinfection (odds ratio, 2.2 [95% confidence interval {CI}, 1.1-4.3]) and a 3-fold higher hazard of having an incident HCV infection (hazard ratio, 3.0 [95% CI, 1.4-6.6]) than individuals with narrow HIV transmission bottlenecks.
  
  
  CONCLUSIONS
  Our results indicate that the currently occurring sexual spread of HCV is focused on MSM who are prone to exhibit broad HIV transmission bottlenecks. This is consistent with an important role of high-risk behavior and mucosal barrier impairment in the transmission of HCV among MSM.
authors.forename: Roger D
authors.initials: RD
authors.lastname: Kouyos
authors.forename: Andri
authors.initials: A
authors.lastname: Rauch
authors.forename: Dominique L
authors.initials: DL
authors.lastname: Braun
authors.forename: Wan-Lin
authors.initials: WL
authors.lastname: Yang
authors.forename: Jürg
authors.initials: J
authors.lastname: Böni
authors.forename: Sabine
authors.initials: S
authors.lastname: Yerly
authors.forename: Thomas
authors.initials: T
authors.lastname: Klimkait
authors.forename: Vincent
authors.initials: V
authors.lastname: Aubert
authors.forename: Cyril
authors.initials: C
authors.lastname: Shah
authors.forename: Helen
authors.initials: H
authors.lastname: Kovari
authors.forename: Alexandra
authors.initials: A
authors.lastname: Calmy
authors.forename: Matthias
authors.initials: M
authors.lastname: Cavassini
authors.forename: Manuel
authors.initials: M
authors.lastname: Battegay
authors.forename: Pietro L
authors.initials: PL
authors.lastname: Vernazza
authors.forename: Enos
authors.initials: E
authors.lastname: Bernasconi
authors.forename: Bruno
authors.initials: B
authors.lastname: Ledergerber
authors.forename: Huldrych F
authors.initials: HF
authors.lastname: Günthard
mesh_terms: D000328:Adult; D015331:Cohort Studies; D060085:Coinfection / Q000453:epidemiology*; D015658:HIV Infections / Q000150:complications*; D006526:Hepatitis C / Q000453:epidemiology* / Q000635:transmission*; D018451:Homosexuality, Male; D006801:Humans; D015994:Incidence; D008297:Male; D015995:Prevalence; D018570:Risk Assessment; D013557:Switzerland / Q000453:epidemiology
keywords: HIV; coinfection; hepatitis C virus; sexual transmission; transmission bottleneck