title: Expanding HIV-1 subtype B transmission networks among men who have sex with men in Poland.
abstract: BACKGROUND
  Reconstruction of HIV transmission links allows to trace the spread and dynamics of infection and guide epidemiological interventions. The aim of this study was to characterize transmission networks among subtype B infected patients from Poland.
  
  
  METHODS
  Maximum likelihood phylogenenetic trees were inferred from 966 HIV-1 subtype B protease/reverse transcriptase sequences from patients followed up in nine Polish HIV centers. Monophyletic clusters were identified using 3% within-cluster distance and 0.9 bootstrap values. Interregional links for the clusters were investigated and time from infection to onward transmission estimated using Bayesian dated MCMC phylogeny.
  
  
  RESULTS
  Three hundred twenty one (33.2%) sequences formed 109 clusters, including ten clusters of ≥5 sequences (n = 81, 8.4%). Transmission networks were more common among MSM (234 sequences, 68.6%) compared to other infection routes (injection drug use: 28 (8.2%) and heterosexual transmissions: 59 (17.3%) cases, respectively [OR:3.5 (95%CI:2.6-4.6),p<0.001]. Frequency of clustering increased from 26.92% in 2009 to 50.6% in 2014 [OR:1.18 (95%CI:1.06-1.31),p = 0.0026; slope +2.8%/year] with median time to onward transmission within clusters of 1.38 (IQR:0.59-2.52) years. In multivariate models clustering was associated with both MSM transmission route [OR:2.24 (95%CI:1.38-3.65),p<0.001] and asymptomatic stage of HIV infection [OR:1.93 (95%CI:1.4-2.64),p<0.0001]. Additionally, interregional networks were linked to MSM transmissions [OR:4.7 (95%CI:2.55-8.96),p<0.001].
  
  
  CONCLUSIONS
  Reconstruction of the HIV-1 subtype B transmission patterns reveals increasing degree of clustering and existence of interregional networks among Polish MSM. Dated phylogeny confirms the association between onward transmission and recent infections. High transmission dynamics among Polish MSM emphasizes the necessity for active testing and early treatment in this group.
authors.affiliation: Department of Infectious, Tropical Diseases and Immune Deficiency, Pomeranian Medical University in Szczecin, Szczecin, Poland.
authors.forename: Miłosz
authors.initials: M
authors.lastname: Parczewski
authors.affiliation: Department of Infectious, Tropical Diseases and Immune Deficiency, Pomeranian Medical University in Szczecin, Szczecin, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Leszczyszyn-Pynka
authors.affiliation: Department of Infectious, Tropical Diseases and Immune Deficiency, Pomeranian Medical University in Szczecin, Szczecin, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Witak-Jędra
authors.affiliation: Department of Infectious Diseases, Hepatology and Acquired Immune Deficiencies, Wrocław Medical University, Wrocław, Poland.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Szetela
authors.affiliation: Department of Infectious Diseases, Hepatology and Acquired Immune Deficiencies, Wrocław Medical University, Wrocław, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Gąsiorowski
authors.affiliation: Department of Infectious Diseases, Hepatology and Acquired Immune Deficiencies, Wrocław Medical University, Wrocław, Poland.
authors.forename: Brygida
authors.initials: B
authors.lastname: Knysz
authors.affiliation: Department of Infectious Diseases, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Bociąga-Jasik
authors.affiliation: Department of Infectious Diseases, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Paweł
authors.initials: P
authors.lastname: Skwara
authors.affiliation: Department of Infectious Diseases and Hepatology, Medical University of Bialystok, Białystok, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Grzeszczuk
authors.affiliation: Department of Infectious Diseases, Medical University in Gdańsk, Gdańsk, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Jankowska
authors.affiliation: Department of Infectious Diseases, J. Strus Hospital, Poznań, Poland.
authors.forename: Grażyna
authors.initials: G
authors.lastname: Barałkiewicz
authors.affiliation: Department of Infectious Diseases, Poznań University of Medical Sciences, Poznań, Poland.
authors.forename: Iwona
authors.initials: I
authors.lastname: Mozer-Lisewska
authors.affiliation: Department of Infectious Diseases, Regional Hospital in Zielona Gora, Zielona Góra, Poland.
authors.forename: Władysław
authors.initials: W
authors.lastname: Łojewski
authors.affiliation: Department of Infectious Diseases, Regional Hospital in Zielona Gora, Zielona Góra, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kozieł
authors.affiliation: Department of Infectious Diseases and Hepatology Nicolaus Copernicus University, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland.
authors.forename: Edyta
authors.initials: E
authors.lastname: Grąbczewska
authors.affiliation: Department of Infectious Diseases and Hepatology, Medical University of Łódź, Łódź, Poland.
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Jabłonowska
authors.affiliation: Department of Infectious, Tropical Diseases and Immune Deficiency, Pomeranian Medical University in Szczecin, Szczecin, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Urbańska
mesh_terms: D000328:Adult; D001499:Bayes Theorem; D016000:Cluster Analysis; D016358:Contact Tracing / Q000706:statistics & numerical data*; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D016333:HIV Protease / Q000235:genetics*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D020010:Heterosexuality; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D010802:Phylogeny; D011044:Poland / Q000453:epidemiology; D062486:Public Health Surveillance; D015819:Substance Abuse, Intravenous / Q000453:epidemiology / Q000821:virology
chemical_list: D016333:HIV Protease; C514803:p16 protease, Human immunodeficiency virus 1