Bridging epidemiology with population genetics in a low incidence MSM-driven HIV-1 subtype B epidemic in Central Europe
Tomažič, Janez (Author), Poljak, Mario (Author), Vovko, Tomaž (Author), Karner, Primož (Author), Lunar, Maja M. (Author), Volčanšek, Gabriele (Author), Pečavar, Blaž (Author), Vandamme, Anne-Mieke (Author), Abecasis, Ana B (Author)

URLURL - Presentation file, Visit http://www.biomedcentral.com/1471-2334/15/65 This link opens in a new window

BACKGROUND: The HIV-1 epidemic in Slovenia, a small Central European country, has some characteristics that make it an ideal model to study HIV-1 transmission. The epidemic is predominantly affecting men who have sex with men infected with subtype B (89% of all patients), has a low prevalence (less than 1/1000) and is growing slowly. The aim of the present study was to analyze in detail the evolutionary history and the determinants of transmission. METHODS: A total of 223 partial pol gene sequences from therapy naïve individuals were included, representing 52% of all patients newly diagnosed in 13 years (2000-2012) and analyzed together with genetically similar worldwide sequences, selected in a BLAST search. RESULTS: Combined analysis (maximum likelihood and Bayesian) of HIV-1 transmission chains revealed 8 major clusters (n >= 10 patients), 1 group of 4 patients, 2 trios and 12 transmission pairs, thus leaving only 43 (19.3%) Slovenian patients infected with subtype B without a local epidemiological link, indicating a predominance of local transmission of HIV-1 infection. Bayesian analysis performed on a full set of sequences estimated several introductions of HIV-1 into Slovenia, with the most recent common ancestor (tMRCA) of the earliest Slovenian cluster dated to the late 1980s, although tMRCAs obtained from separate independent analysis of each cluster showed considerably more recent estimates. These findings indicate inconsistencies in molecular clock estimation, which we further explored. We hypothesize that these inconsistent dating estimates across the tree could be caused by an evolutionary rate acceleration of HIV-1 after entering the Slovenia epidemic that is not taken into account by the molecular clock model. It could be caused by a lower transmission rate in this setting, as demonstrated by the low epidemic growth rate estimated by Bayesian skyline plot analysis. CONCLUSIONS: HIV-1 subtype B was introduced into Slovenia at several time points from the late 80s onward. The majority of patients had a local transmission link, indicating a closed HIV community. The observed slower epidemic rate suggests that individuals with a long-lasting infection are the driving force of the epidemic in this region.

Keywords:HIV-1, subtype B, molecular edpiemiology, phylogeny, phylodinamics, substitution rate
Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:MF - Faculty of Medicine
Number of pages:str. 65 [12 str.]
Numbering:Vol. 15, no. 1
ISSN on article:1471-2334
DOI:10.1186/s12879-015-0802-6 Link is opened in a new window
COBISS.SI-ID:31957465 Link is opened in a new window
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Record is a part of a journal

Title:BMC infectious diseases
Shortened title:BMC Infect Dis
Publisher:BioMed Central
COBISS.SI-ID:2439444 This link opens in a new window

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