title: Evolution and molecular epidemiology of subtype C HIV-1 in Zimbabwe.
abstract: OBJECTIVE
  To investigate the origins and evolutionary history of subtype C HIV-1 in Zimbabwe in a context of regional conflict and migration.
  
  
  METHODS
  HIV-1C pol sequence datasets were generated from four sequential cohorts of antenatal women in Harare, Zimbabwe sampled over 15 years (1991-2006).
  
  
  METHODS
  One hundred and seventy-seven HIV-1C pol sequences were obtained from four successive cohorts in Zimbabwe. Maximum-likelihood methods were used to explore phylogenetic relationships between Zimbabwean HIV-1C sequences and subtype C strains from other regions. A Bayesian coalescent-based framework was used to estimate evolutionary parameters for HIV-1C in Zimbabwe, including origin and demographic growth patterns.
  
  
  RESULTS
  Zimbabwe HIV-1C pol demonstrated increasing sequence divergence over the 15-year period. Nearly all Zimbabwe sequences clustered phylogenetically with subtype C strains from neighboring countries. Bayesian evolutionary analysis indicated a most recent common ancestor date of 1973 with three epidemic growth phases: an initial, slow phase (1970s) followed by exponential growth (1980s), and a linearly expanding epidemic to the present. Bayesian trees provided evidence for multiple HIV-1C introductions into Zimbabwe during 1979-1981, corresponding with Zimbabwean national independence following a period of socio-political instability.
  
  
  CONCLUSIONS
  The Zimbabwean HIV-1C epidemic likely originated from multiple introductions in the late 1970s and grew exponentially during the 1980s, corresponding to changing political boundaries and rapid population influx from neighboring countries. The timing and phylogenetic clustering of the Zimbabwean sequences is consistent with an origin in southern Africa and subsequent expansion. HIV-1 sequence data contain important epidemiological information, which can help focus treatment and prevention strategies in light of more recent political volatility in Zimbabwe.
authors.affiliation: Stanford University School of Medicine, Stanford University Medical Center, Stanford, CA 94305, USA. sdalai@stanford.edu
authors.forename: Sudeb C
authors.initials: SC
authors.lastname: Dalai
authors.forename: Tulio
authors.initials: T
authors.lastname: de Oliveira
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Harkins
authors.forename: Seble G
authors.initials: SG
authors.lastname: Kassaye
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lint
authors.forename: Justen
authors.initials: J
authors.lastname: Manasa
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Johnston
authors.forename: David
authors.initials: D
authors.lastname: Katzenstein
mesh_terms: D000328:Adult; D019143:Evolution, Molecular; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology; D015497:HIV-1 / Q000145:classification* / Q000235:genetics; D006801:Humans; D017720:Molecular Epidemiology; D010802:Phylogeny; D015030:Zimbabwe / Q000453:epidemiology