title: High frequency of HIV-1 dual infections among HIV-positive individuals in Cameroon, West Central Africa.
abstract: OBJECTIVE
  To determine the frequency of dual inter- and intra-subtype HIV-1 infection among a cohort of 64 longitudinally-studied, HIV-1-positive individuals in Yaoundé, Cameroon.
  
  
  METHODS
  Blood was collected every 3-6 months for up to 36 months and RNA was extracted from plasma. Gag fragment (HxB2 location 1577-2040) was amplified by nested RT-PCR, and mixed-time-point Heteroduplex Assays (HDAs) were performed. As heteroduplexes in this assay indicate >or=5% genetic discordance in the gag fragment, their presence reveals dual infection. Results were confirmed by phylogenetic analysis.
  
  
  RESULTS
  Heteroduplexes were generated by specimens of 10 subjects (15.6%). Kaplan-Meier nonparametric estimate of maintenance of single infection was calculated; the rate/year of a 2 infection was found to be approximately 11%. Dual infection was identified in the final specimens of five subjects, after as much as 18 months follow-up, while for the remaining five subjects, dual infection was identified in interim specimens within an average of 10 months follow-up. Analysis of samples obtained after dual infection from each of these latter five subjects revealed two patterns: reversion to initial strain, or replacement of initial strain. Four subjects were dually-infected with HIV-1 strains of the same subtype, while 6 were infected with different subtypes.
  
  
  CONCLUSIONS
  The high prevalence of recombinant HIV-1 strains in Cameroon may in part be explained by the high frequency of dual infection. In this genetically-diverse HIV-1 milieu, dual infections and the recombinant viruses they generate are strongly driving viral evolution, complicating vaccine strategies.
authors.affiliation: Department of Microbiology, New York University School of Medicine, New York, NY 10010, USA.
authors.forename: Rebecca L R
authors.initials: RL
authors.lastname: Powell
authors.forename: Mateusz M
authors.initials: MM
authors.lastname: Urbanski
authors.forename: Sherri
authors.initials: S
authors.lastname: Burda
authors.forename: Thompson
authors.initials: T
authors.lastname: Kinge
authors.forename: Phillipe N
authors.initials: PN
authors.lastname: Nyambi
mesh_terms: D000293:Adolescent; D000328:Adult; D002163:Cameroon / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D055815:Young Adult