title: Incidence of human immunodeficiency virus type 1 dual infections in Amsterdam, The Netherlands, during 2003-2007.
abstract: BACKGROUND
  The occurrence of human immunodeficiency virus type 1 (HIV-1) dual infections in Amsterdam, The Netherlands, was examined during 2003-2007 to investigate whether the number of HIV-1 dual infections increased as the number of HIV-1 infected individuals increased during the same period.
  
  
  METHODS
  All first HIV-1 genotyping sequences obtained from 2003 through 2007 were retrieved and examined for the number of degenerate base codes in the reverse-transcriptase fragment. A total of 72 patients had >or=34 degenerate base codes; for these patients, a fragment of the V3-V4 region of the env gene was amplified, cloned, and sequenced to verify the presence of an HIV-1 dual infection. The number of dual infections were counted for each year investigated.
  
  
  RESULTS
  No significant change in the incidence of dual infections was observed in our population of patients, who were selected on the basis of the number of degenerate base codes in each patient's first HIV-1 sequence obtained from 2003 through 2007. The frequency of HIV-1 dual infections varied between 1.0% and 2.4% each year, with no significant trend over time (P = .49). Patients with HIV-1 dual infections were similar to patients with single HIV-1 infections in The Netherlands with regard to distribution of risk group, sex, and HIV subtype.
  
  
  CONCLUSIONS
  The proportion of HIV-1 dual infections in The Netherlands did not increase from 2003 through 2007, although the HIV-1-infected population expanded in this period.
authors.affiliation: Department of Medical Microbiology, Laboratory of Experimental Virology, Center for Infection and Immunity Amsterdam, Amsterdam, The Netherlands. a.c.vanderkuyl@amc.uva.nl
authors.forename: Antoinette C
authors.initials: AC
authors.lastname: van der Kuyl
authors.forename: Fokla
authors.initials: F
authors.lastname: Zorgdrager
authors.forename: Suzanne
authors.initials: S
authors.lastname: Jurriaans
authors.forename: Nicole K T
authors.initials: NK
authors.lastname: Back
authors.forename: Jan M
authors.initials: JM
authors.lastname: Prins
authors.forename: Kees
authors.initials: K
authors.lastname: Brinkman
authors.forename: Arne
authors.initials: A
authors.lastname: van Eeden
authors.forename: Margreet
authors.initials: M
authors.lastname: Bakker
authors.forename: Marion
authors.initials: M
authors.lastname: Cornelissen
mesh_terms: D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology*; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D015994:Incidence; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D017422:Sequence Analysis, DNA; D054299:env Gene Products, Human Immunodeficiency Virus / Q000235:genetics
chemical_list: D054299:env Gene Products, Human Immunodeficiency Virus; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase