title: Brief but efficient: acute HIV infection and the sexual transmission of HIV.
abstract: BACKGROUND
  We examined whether viral dynamics in the genital tract during the natural history of acute human immunodeficiency virus type 1 (HIV-1) infection could explain efficient heterosexual transmission of HIV.
  
  
  METHODS
  We measured HIV-1 concentration in blood and semen samples from patients with acute and long-term HIV-1 infection. We explored the effect of changes in viral dynamics in semen on the probability of transmission per coital act, using a probabilistic model published elsewhere.
  
  
  RESULTS
  Considered over time from infection, semen HIV-1 concentrations, in men with acute infection, increase and decrease in approximate parallel with changes occurring in blood. Modeling suggests that these acute dynamics alone are sufficient to increase probability of heterosexual transmission by 8-10-fold between peak (day 20 after infection, based on the model) and virologic set points (day 54 and later after infection). Depending on the frequency of coitus, men with average semen HIV-1 loads and without sexually transmitted diseases (STDs) would be expected to infect 7%-24% of susceptible female sex partners during the first 2 months of infection. The predicted infection rate would be much higher when either partner has an STD.
  
  
  CONCLUSIONS
  Empirical biological data strongly support the hypothesis that sexual transmission by acutely infected individuals has a disproportionate effect on the spread of HIV-1 infection. Acute hyperinfectiousness may, in part, explain the current pandemic in heterosexual individuals.
authors.affiliation: Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. cpilcher@med.unc.edu.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Pilcher
authors.forename: Hsiao Chuan
authors.initials: HC
authors.lastname: Tien
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Eron
authors.forename: Pietro L
authors.initials: PL
authors.lastname: Vernazza
authors.forename: Szu-Yun
authors.initials: SY
authors.lastname: Leu
authors.forename: Paul W
authors.initials: PW
authors.lastname: Stewart
authors.forename: Li-Ean
authors.initials: LE
authors.lastname: Goh
authors.forename: Myron S
authors.initials: MS
authors.lastname: Cohen
mesh_terms: D015331:Cohort Studies; D003075:Coitus; D018562:Disease Transmission, Infectious; D005260:Female; D015658:HIV Infections / Q000097:blood / Q000276:immunology / Q000635:transmission*; D015497:HIV-1 / Q000235:genetics / Q000276:immunology; D006801:Humans; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D012367:RNA, Viral / Q000097:blood / Q000276:immunology; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012661:Semen / Q000821:virology; D014766:Viremia / Q000276:immunology / Q000635:transmission
chemical_list: D012367:RNA, Viral