title: Acute HIV infection: impact on the spread of HIV and transmission of drug resistance.
abstract: OBJECTIVE
  To assess the impact of primary HIV infection (PHI) on the spread of HIV and the temporal trends in transmission of HIV drug resistance between 1996 and 1999 in Switzerland.
  
  
  METHODS
  Sequencing of the genes for reverse transcriptase (RT) and protease was performed for 197 individuals with documented PHI. Phylogenetic analyses were confronted with epidemiological data.
  
  
  RESULTS
  Significant clustering was demonstrated for 29% of the RT sequences. All these cases occurred closely together in place and time; contact tracing demonstrated transmission at the time of PHI in 30% of them. Genotypic drug resistance was detected in 8.6% of PHI individuals in 1996, 14.6% in 1997, 8.8% in 1998 and 5.0% in 1999. Drug-resistant variants were identified in 11.3% of individuals infected by homosexual contacts, 6.1% by heterosexual contacts, 13% of intravenous drug users and more frequently in men (10.4%) than women (2.6%). Potential factors involved in the recent decrease of transmission of drug-resistant variants include increase of HIV non-B subtypes from 23% in 1996 to 35% in 1999 (only one non-B subtype had resistance mutations) and a steady increase of patients with undetectable viraemia as documented in Swiss HIV Cohort Study (10% in 1996 vs 53% in 1999).
  
  
  CONCLUSIONS
  Phylogenetic and epidemiological analyses underline the impact of PHI in the spread of HIV. Moreover, this study indicates that drug resistance transmission may have decreased recently in Switzerland through the increased frequency of infection with HIV non-B subtypes and the steady increase of patients with undetectable viraemia.
authors.affiliation: University Hospital of Geneva, 1211 Geneva 14, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Yerly
authors.forename: S
authors.initials: S
authors.lastname: Vora
authors.forename: P
authors.initials: P
authors.lastname: Rizzardi
authors.forename: J P
authors.initials: JP
authors.lastname: Chave
authors.forename: P L
authors.initials: PL
authors.lastname: Vernazza
authors.forename: M
authors.initials: M
authors.lastname: Flepp
authors.forename: A
authors.initials: A
authors.lastname: Telenti
authors.forename: M
authors.initials: M
authors.lastname: Battegay
authors.forename: A L
authors.initials: AL
authors.lastname: Veuthey
authors.forename: J P
authors.initials: JP
authors.lastname: Bru
authors.forename: M
authors.initials: M
authors.lastname: Rickenbach
authors.forename: B
authors.initials: B
authors.lastname: Hirschel
authors.forename: L
authors.initials: L
authors.lastname: Perrin
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D015658:HIV Infections / Q000453:epidemiology / Q000276:immunology / Q000635:transmission* / Q000821:virology; D016333:HIV Protease / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D013557:Switzerland / Q000453:epidemiology
chemical_list: D054303:HIV Reverse Transcriptase; D016333:HIV Protease