title: Discordance in HIV-1 viral loads and antiretroviral drug concentrations comparing semen and blood plasma.
abstract: OBJECTIVE
  For individuals not on antiretroviral therapy, the risk of heterosexual transmission of HIV appears negligible when blood plasma (BP) viral loads are <1500 HIV-1 RNA copies/mL. It is not clear whether this observation can be extrapolated to individuals on highly active antiretroviral therapy (HAART). Because of differential tissue penetration, antiretroviral drug concentrations may be sufficient to maintain an undetectable viral load in the BP yet not achieve adequate levels to suppress HIV in the genital tract. Therefore, we wanted to correlate HIV viral loads and drug concentrations in semen plasma (SP) and BP.
  
  
  METHODS
  Thirty-three men were included. All were on combination antiretroviral therapy with an undetectable BP viral load for at least 1 year. Blood and semen samples were collected within 2 h of each other and tested for HIV RNA by the NucliSens QT (bioMerieux, St Laurent, QC, Canada) method; drug concentrations were determined by liquid chromatography tandem mass spectrometry.
  
  
  RESULTS
  Two of the 33 patients (6.1%) with BP viral loads below detection had time-matched HIV viral loads in SP > or =700 copies/mL. Both patients were on efavirenz, the SP concentrations of which were < or =10% of the levels in BP and well below the minimal therapeutic drug monitoring target concentration required to suppress HIV.
  
  
  CONCLUSIONS
  Because, at least in part, of poor drug penetration into the genital tract, an undetectable HIV viral load in the BP does not guarantee an undetectable viral load in semen. In view of this, caution should be taken in concluding that patients on HAART with suppressed viraemia are sexually non-infectious.
authors.affiliation: Faculty of Medicine, University of Ottawa, Ottawa, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Lorello
authors.forename: C
authors.initials: C
authors.lastname: la Porte
authors.forename: R
authors.initials: R
authors.lastname: Pilon
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Karnauchow
authors.forename: P
authors.initials: P
authors.lastname: MacPherson
mesh_terms: D000328:Adult; D000368:Aged; D019380:Anti-HIV Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D023241:Antiretroviral Therapy, Highly Active; D003430:Cross-Sectional Studies; D015658:HIV Infections / Q000188:drug therapy* / Q000378:metabolism / Q000635:transmission; D015497:HIV-1 / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000032:analysis / Q000097:blood; D012661:Semen / Q000378:metabolism / Q000821:virology*; D014018:Tissue Distribution; D019562:Viral Load / Q000379:methods
chemical_list: D019380:Anti-HIV Agents; D012367:RNA, Viral