title: Genetic diversity of HIV-1 in western Kenya: subtype-specific differences in mother-to-child transmission.
abstract: BACKGROUND
  Little is known about the impact of HIV-1 group M subtypes on mother-to-child transmission (MTCT) of HIV-1 in African settings where multiple HIV-1 group M subtypes are co-circulating.
  
  
  OBJECTIVE
  To assess the role of subtype variation on MTCT.
  
  
  METHODS
  HIV-1-infected women attending an antenatal clinic in western Kenya were enrolled for a prospective study (1996-2000) of MTCT. HIV-1 subtype analysis of p24gag and gp41env identified potential recombinants, and their role in MTCT was determined.
  
  
  RESULTS
  Among 414 women for whom HIV-1 subtype and HIV transmission status were available, MTCT occurred in 80 (19.3%). MTCT rates were higher among women with subtype D compared with subtype A in either the gp41 region [31.6 versus 16.1%, relative risk (RR) 2.0, P=0.002] or p24 region (29.9 versus 18.0%, RR 1.7, P=0.02). Discordant subtype combinations were identified in 103 of the women (25.9%), and were associated with higher rates of MTCT (28.2 versus 17.0%, RR 1.7, P=0.01). In multivariate analysis, women with subtype combinations D/D, D/A, and A/D had an increased risk of MTCT (adjusted odds ratios 3.5, 2.5, 6.2; P=0.005, 0.05, and 0.0003, respectively) compared with A/A women after adjustment for maternal HIV viral load, placental malaria infection, episiotomy or perineal tear, and low birthweight.
  
  
  CONCLUSIONS
  MTCT appears to be more common among mothers infected with subtype D compared with subtype A. Such differences in MTCT frequency may be caused by altered cellular tropism for placental cell types.
authors.affiliation: Division of AIDS, STD, and TB Laboratory Research, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Chunfu
authors.initials: C
authors.lastname: Yang
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Robert D
authors.initials: RD
authors.lastname: Newman
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Shi
authors.forename: John
authors.initials: J
authors.lastname: Ayisi
authors.forename: Anna M
authors.initials: AM
authors.lastname: van Eijk
authors.forename: Juliana
authors.initials: J
authors.lastname: Otieno
authors.forename: Ambrose O
authors.initials: AO
authors.lastname: Misore
authors.forename: Richard W
authors.initials: RW
authors.lastname: Steketee
authors.forename: Bernard L
authors.initials: BL
authors.lastname: Nahlen
authors.forename: Renu B
authors.initials: RB
authors.lastname: Lal
mesh_terms: D005260:Female; D016655:HIV Core Protein p24 / Q000235:genetics; D015700:HIV Envelope Protein gp41 / Q000235:genetics; D015658:HIV Infections / Q000635:transmission* / Q000821:virology*; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D018445:Infectious Disease Transmission, Vertical; D007630:Kenya; D016015:Logistic Models; D009154:Mutation; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000821:virology*; D011446:Prospective Studies; D012367:RNA, Viral / Q000032:analysis; D012307:Risk Factors; D019562:Viral Load
chemical_list: D016655:HIV Core Protein p24; D015700:HIV Envelope Protein gp41; D012367:RNA, Viral