title: Increasing prevalence of HIV-1 subtype A in Greece: estimating epidemic history and origin.
abstract: BACKGROUND
  In North America and Europe, human immunodeficiency virus (HIV)-1 infection has typically been dominated by subtype B transmission. More recently, however, non-B subtypes have been increasingly reported in Europe.
  
  
  METHODS
  We analyzed 1158 HIV-1-infected individuals in Greece by DNA sequencing and phylogenetic analyses of protease and partial reverse-transcriptase regions.
  
  
  RESULTS
  We found that the prevalence of non-B subtypes has increased over time and that this significant trend can be mainly attributed to subtype A, which eventually surpassed subtype B in prevalence in 2004 (42% and 33%, respectively). Multivariate analysis revealed that the year of HIV diagnosis was independently associated with subtype A infection (odds ratio for being infected with subtype A for a 10-year increase in the time period of diagnosis, 2.09 [95% confidence interval, 1.36-3.24]; P<.001). Phylogenetic analysis revealed that the subtype A epidemic in Greece is the result of a single founder event. The date of the most recent common ancestor of the subtype A in Greece was estimated to be 1977.9 (95% highest posterior density interval, 1973.7-1981.9).
  
  
  CONCLUSIONS
  Subtype A circulates among the long-term residents of Greece. This is in contrast to the situation in most European countries, in which infection with non-B genetic forms is associated either with being an immigrant or heterosexual or with intravenous drug use.
authors.affiliation: Department of Hygiene and Epidemiology, National Retrovirus Reference Center, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Paraskevis
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Magiorkinis
authors.forename: Gkikas
authors.initials: G
authors.lastname: Magiorkinis
authors.forename: Vana
authors.initials: V
authors.lastname: Sypsa
authors.forename: Vassilios
authors.initials: V
authors.lastname: Paparizos
authors.forename: Marios
authors.initials: M
authors.lastname: Lazanas
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Gargalianos
authors.forename: Anastasia
authors.initials: A
authors.lastname: Antoniadou
authors.forename: Georgios
authors.initials: G
authors.lastname: Panos
authors.forename: Georgios
authors.initials: G
authors.lastname: Chrysos
authors.forename: Helen
authors.initials: H
authors.lastname: Sambatakou
authors.forename: Anastasia
authors.initials: A
authors.lastname: Karafoulidou
authors.forename: Athanasios
authors.initials: A
authors.lastname: Skoutelis
authors.forename: Theodoros
authors.initials: T
authors.lastname: Kordossis
authors.forename: Georgios
authors.initials: G
authors.lastname: Koratzanis
authors.forename: Maria
authors.initials: M
authors.lastname: Theodoridou
authors.forename: Georgios L
authors.initials: GL
authors.lastname: Daikos
authors.forename: Georgios
authors.initials: G
authors.lastname: Nikolopoulos
authors.forename: Oliver G
authors.initials: OG
authors.lastname: Pybus
authors.forename: Angelos
authors.initials: A
authors.lastname: Hatzakis
mesh_terms: D000328:Adult; D005260:Female; D014644:Genetic Variation; D006115:Greece / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology / Q000235:genetics*; D016333:HIV Protease / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D015995:Prevalence
chemical_list: D054303:HIV Reverse Transcriptase; D016333:HIV Protease