Saturday, March 12, 2016

Characterization of HIV Transmission in South-East Austria

To gain deeper insight into the epidemiology of HIV-1 transmission in South-East Austria we performed a retrospective analysis of 259 HIV-1 partial pol sequences obtained from unique individuals newly diagnosed with HIV infection in South-East Austria from 2008 through 2014. 

After quality filtering, putative transmission linkages were inferred when two sequences were ≤1.5% genetically different. Multiple linkages were resolved into putative transmission clusters. Further phylogenetic analyses were performed using BEAST v1.8.1. Finally, we investigated putative links between the 259 sequences from South-East Austria and all publicly available HIV polymerase sequences in the Los Alamos National Laboratory HIV sequence database. 

We found that 45.6% (118/259) of the sampled sequences were genetically linked with at least one other sequence from South-East Austria forming putative transmission clusters. Clustering individuals were more likely to be men who have sex with men (MSM; p<0.001), infected with subtype B (p<0.001) or subtype F (p = 0.02). Among clustered males who reported only heterosexual (HSX) sex as an HIV risk, 47% clustered closely with MSM (either as pairs or within larger MSM clusters). One hundred and seven of the 259 sequences (41.3%) from South-East Austria had at least one putative inferred linkage with sequences from a total of 69 other countries. 

In conclusion, analysis of HIV-1 sequences from newly diagnosed individuals residing in South-East Austria revealed a high degree of national and international clustering mainly within MSM. Interestingly, we found that a high number of heterosexual males clustered within MSM networks, suggesting either linkage between risk groups or misrepresentation of sexual risk behaviors by subjects.

Below:  Intersection between the Global HIV Type 1 Endemic and South East Austria. A total of 107 (41.3%) of 259 sequences obtained in South-East Austria shared a putative link with sequences from foreign countries/regions. In this heat map with a gradient from 1 to 40 linkages, countries are colored by the number of putative links from yellow to red (i.e. red is 40 or more linkages). Unlinked countries are colored in white. 

Full article at:

Martin Hoenigl, Antoine Chaillon, Susan J. Little, Sanjay R. Mehta
Division of Infectious Diseases, University of California San Diego, San Diego, California, United States of America

Martin Hoenigl
Section of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Medical University of Graz, Graz, Austria

Martin Hoenigl
Division of Pulmonology, Department of Internal Medicine, Medical University of Graz, Graz, Austria

Harald H. Kessler, Evelyn Stelzl, Karin Weninger
Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria

Bernhard Haas
Department of Infectious Diseases, Landeskrankenhaus Graz West, Graz, Austria

Sanjay R. Mehta
Veterans Affairs Healthcare System, San Diego, California, United States of America

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