title: High rates of forward transmission events after acute/early HIV-1 infection.
abstract: BACKGROUND
  A population-based phylogenetic approach was used to characterize human immunodeficiency virus (HIV)-transmission dynamics in Quebec.
  
  
  METHODS
  HIV-1 pol sequences included primary HIV infections (PHIs; <6 months after seroconversion) from the Quebec PHI cohort (1998-2005; n=215) and the provincial genotyping program (2001-2005; n=481). Phylogenetic analysis determined sequence interrelationships among unique PHIs (n=593) and infections from untreated (n=135) and treated (n=660) chronically infected (CI) potential transmitter populations (2001-2005). Clinical features, risk factors, and drug resistance for clustered and nonclustered transmission events were ascertained.
  
  
  RESULTS
  Viruses from 49.4% (293/593) of PHIs cosegregated into 75 transmission chains with 2-17 transmissions/cluster. Half of the clusters included 2.7+/-0.8 (mean+/-SD) transmissions, whereas the remainder had 8.8+/-3.5 transmissions. Maximum periods for onward transmission in clusters were 15.2+/-9.5 months. Coclustering of untreated and treated CIs with PHIs were infrequent (6.2% and 4.8%, respectively). The ages, viremia, and risk factors were similar for clustered and nonclustered transmission events. Low prevalence of drug resistance in PHI supported amplified transmissions at early stages.
  
  
  CONCLUSIONS
  Early infection accounts for approximately half of onward transmissions in this urban North American study. Therapy at early stages of disease may prevent onward HIV transmission.
authors.affiliation: McGill AIDS Centre-Jewish General Hospital, Montreal, Canada.
authors.forename: Bluma G
authors.initials: BG
authors.lastname: Brenner
authors.forename: Michel
authors.initials: M
authors.lastname: Roger
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Routy
authors.forename: Daniela
authors.initials: D
authors.lastname: Moisi
authors.forename: Michel
authors.initials: M
authors.lastname: Ntemgwa
authors.forename: Claudine
authors.initials: C
authors.lastname: Matte
authors.forename: Jean-Guy
authors.initials: JG
authors.lastname: Baril
authors.forename: Rejéan
authors.initials: R
authors.lastname: Thomas
authors.forename: Danielle
authors.initials: D
authors.lastname: Rouleau
authors.forename: Julie
authors.initials: J
authors.lastname: Bruneau
authors.forename: Roger
authors.initials: R
authors.lastname: Leblanc
authors.forename: Mario
authors.initials: M
authors.lastname: Legault
authors.forename: Cecile
authors.initials: C
authors.lastname: Tremblay
authors.forename: Hugues
authors.initials: H
authors.lastname: Charest
authors.forename: Mark A
authors.initials: MA
authors.lastname: Wainberg
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use; D004279:DNA, Viral / Q000032:analysis; D018562:Disease Transmission, Infectious; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D015751:Genes, pol; D014644:Genetic Variation; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000209:etiology / Q000635:transmission* / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D008297:Male; D010802:Phylogeny; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors
chemical_list: D019380:Anti-HIV Agents; D004279:DNA, Viral