title: Characterization of human immunodeficiency virus type 1 (HIV-1) diversity and tropism in 145 patients with primary HIV-1 infection.
abstract: BACKGROUND
  In the context of sexual transmission of human immunodeficiency virus type 1 (HIV-1), current findings suggest that the mucosal barrier is the major site of viral selection, transforming the complex inoculum to a small, homogeneous founder virus population. We analyzed HIV-1 transmission in relation to viral and host characteristics within the Zurich primary HIV-1 infection study.
  
  
  METHODS
  Clonal HIV-1 envelope sequences (on average 16 clones/patient) were isolated from the first available plasma samples during the early phase of infection from 145 patients with primary HIV-1 infection. Phylogenetic and tropism analyses were performed. Differences of viral diversities were investigated in association with several parameters potentially influencing HIV-1 transmission, eg, concomitant sexually transmitted infections (STIs) and mode of transmission.
  
  
  RESULTS
  Median viral diversity within env C2-V3-C3 region was 0.39% (range 0.04%-3.23%). Viral diversity did not correlate with viral load, but it was slightly correlated with the duration of infection. Neither transmission mode, gender, nor STI predicted transmission of more heterogeneous founder virus populations that were found in 16 of 145 patients (11%; diversity >1%). Only 2 patients (1.4%) were assuredly infected with CXCR4-tropic HIV-1 within a R5/X4-tropic--mixed population, as revealed and confirmed using several genotypic prediction algorithms and phenotypic assays.
  
  
  CONCLUSIONS
  Our findings suggest that transmission of multiple HIV-1 variants might be a complex process that is not dependent on mucosal factors alone. CXCR4-tropic viruses can be sexually transmitted in rare instances, but their clinical relevance remains to be determined.
authors: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Switzerland.
authors: Philip
authors: P
authors: Rieder
authors: Beda
authors: B
authors: Joos
authors: Alexandra U
authors: AU
authors: Scherrer
authors: Herbert
authors: H
authors: Kuster
authors: Dominique
authors: D
authors: Braun
authors: Christina
authors: C
authors: Grube
authors: Barbara
authors: B
authors: Niederöst
authors: Christine
authors: C
authors: Leemann
authors: Sara
authors: S
authors: Gianella
authors: Karin J
authors: KJ
authors: Metzner
authors: Jürg
authors: J
authors: Böni
authors: Rainer
authors: R
authors: Weber
authors: Huldrych F
authors: HF
authors: Günthard
mesh_terms: D000328:Adult; D000368:Aged; D016000:Cluster Analysis; D005260:Female; D014644:Genetic Variation; D015658:HIV Infections / Q000635:transmission* / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013557:Switzerland; D056189:Viral Tropism; D055815:Young Adult; D054299:env Gene Products, Human Immunodeficiency Virus / Q000235:genetics
chemical_list: D054299:env Gene Products, Human Immunodeficiency Virus