title: Risk of HIV-1 transmission by breastfeeding among mothers infected with recombinant and non-recombinant HIV-1 genotypes.
abstract: BACKGROUND
  Viral genotype and intersubtype recombination may influence the rate and/or timing of mother-to-child HIV-1 transmission.
  
  
  METHODS
  We determined the HIV-1 subtype of the C2-C5 env and 5'LTR regions from milk and blood samples of 61 Tanzanian mothers who transmitted the virus through breastfeeding and their HIV-1 positive non-transmitting controls. Cases and controls were matched on infant's age at sample collection. All mothers resided in Dar es Salaam, Tanzania.
  
  
  RESULTS
  Most infections among cases were due to recombinant viruses (41.0%), followed by HIV-1 subtype A (26.2%), subtype D (19.7%), and subtype C (13.1%). In multivariate analysis including maternal CD4+ cell counts, HIV disease stage, and proviral load in breast milk, the odds of breast milk transmission were 7.2 times higher if the mother carried an intersubtype recombinant genome in comparison to a subtype C virus (p=0.02). Viruses with recombinant LTRs were 4.9 times more likely to be transmitted through breastfeeding than viruses with non-recombinant LTRs of subtype A, C or D combined (p=0.01).
  
  
  CONCLUSIONS
  This suggested that intersubtype recombinant genomes, and especially recombination within the LTR, might render HIV-1 more fit for transmission via breast milk in comparison with non-recombinant subtypes A, C, and D.
authors.affiliation: Harvard School of Public Health AIDS Initiative, and Department of Immunology and Infectious Diseases, Harvard School of Public Health, FXB-402, 651 Huntington Avenue, Boston, MA 02115, USA. ikoulins@hsph.harvard.edu
authors.forename: Irene N
authors.initials: IN
authors.lastname: Koulinska
authors.forename: Eduardo
authors.initials: E
authors.lastname: Villamor
authors.forename: Gernard
authors.initials: G
authors.lastname: Msamanga
authors.forename: Wafaie
authors.initials: W
authors.lastname: Fawzi
authors.forename: Jason
authors.initials: J
authors.lastname: Blackard
authors.forename: Boris
authors.initials: B
authors.lastname: Renjifo
authors.forename: Max
authors.initials: M
authors.lastname: Essex
mesh_terms: D000328:Adult; D001942:Breast Feeding / Q000009:adverse effects / Q000453:epidemiology*; D018791:CD4 Lymphocyte Count; D018450:Disease Progression; D005260:Female; D016325:HIV Long Terminal Repeat / Q000235:genetics; D006679:HIV Seropositivity / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology / Q000635:transmission*; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D008895:Milk, Human / Q000821:virology; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D011995:Recombination, Genetic; D012307:Risk Factors; D013045:Species Specificity; D013636:Tanzania / Q000453:epidemiology; D019562:Viral Load