title: HIV-1 transmission between MSM and heterosexuals, and increasing proportions of circulating recombinant forms in the Nordic Countries.
abstract: Increased knowledge about HIV-1 transmission dynamics in different transmission groups and geographical regions is fundamental for assessing and designing prevention efforts against HIV-1 spread. Since the first reported cases of HIV infection during the early 1980s, the HIV-1 epidemic in the Nordic countries has been dominated by HIV-1 subtype B and MSM transmission. HIV-1polsequences and clinical data of 51 per cent of all newly diagnosed HIV-1 infections in Sweden, Denmark, and Finland in the period 2000-2012 (N= 3,802) were analysed together with a large reference sequence dataset (N= 4,537) by trend analysis and phylogenetics. Analysis of the eight dominating subtypes and CRFs in the Nordic countries (A, B, C, D, G, CRF01_AE, CRF02_AG, and CRF06_cpx) showed that the subtype B proportion decreased while the CRF proportion increased over the study period. A majority (57 per cent) of the Nordic sequences formed transmission clusters, with evidence of mixing both geographically and between transmission groups. Detailed analyses showed multiple occasions of transmissions from MSM to heterosexuals and that active transmission clusters more often involved single than multiple Nordic countries. The strongest geographical link was between Denmark and Sweden. Finally, Denmark had a larger proportion of heterosexual domestic spread of HIV-1 subtype B (75 per cent) compared with Sweden (49 per cent) and Finland (57 per cent). We describe different HIV-1 transmission patterns between countries and transmission groups in a large geographical region. Our results may have implications for public health interventions in targeting HIV-1 transmission networks and identifying where to introduce such interventions.
authors: Department of Microbiology Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden; Nuffield Department of Medicine, University of Oxford, Oxford, UK; REGA Institute, Katholieke Universiteit, Leuven, Belgium.
authors: Joakim
authors: J
authors: Esbjörnsson
authors: Department of Microbiology, Public Health Agency of Sweden, Stockholm, Sweden.
authors: Mattias
authors: M
authors: Mild
authors: Department of Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen, Denmark.
authors: Anne
authors: A
authors: Audelin
authors: Department of Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen, Denmark.
authors: Jannik
authors: J
authors: Fonager
authors: Department of Science and Technology, Linköping University, Campus Norrköping, Norrköping, Sweden.
authors: Helena
authors: H
authors: Skar
authors: Department of Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen, Denmark.
authors: Louise
authors: L
authors: Bruun Jørgensen
authors: Department of Infectious Diseases, National Institute for Health and Welfare, Helsinki, Finland.
authors: Kirsi
authors: K
authors: Liitsola
authors: Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
authors: Per
authors: P
authors: Björkman
authors: Department of Clinical Science and Education, Venhälsan, Stockholm South General Hospital, Stockholm, Sweden.
authors: Göran
authors: G
authors: Bratt
authors: Department of Infectious Diseases, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
authors: Magnus
authors: M
authors: Gisslén
authors: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden; Division of Clinical Microbiology, Karolinska Institute, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
authors: Anders
authors: A
authors: Sönnerborg
authors: Department of Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen, Denmark.
authors: Claus
authors: C
authors: Nielsen
authors: Department of Translational Medicine, Lund University, Malmö, Sweden.
authors: Patrik
authors: P
authors: Medstrand
authors: Department of Microbiology Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden; Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.
authors: Jan
authors: J
authors: Albert
keywords: HIV-1; molecular epidemiology; phylogeny; subtype; transmission