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Earlier initiation of antiretroviral treatment coincides with an initial control of the HIV-1 sub-subtype F1 outbreak among men-having-sex-with-men in Flanders, Belgium



Laboratory of Clinical and Epidemiological Virology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
AIDS Reference Laboratory, University Hospitals Leuven, Leuven, Belgium

HIV-1 non-B subtype infections occurred in Belgium since the 1980s, mainly amongst migrants and heterosexuals, whereas subtype B predominated in men-having-sex-with-men (MSM). In the last decade, the diagnosis of F1 sub-subtype in particular has increased substantially, which prompted us to perform a detailed reconstruction of its epidemiological history. To this purpose, the Belgian AIDS Reference Laboratories collected HIV-1 pol sequences from all sub-subtype F1-infected patients for whom genotypic drug resistance testing was requested as part of routine clinical follow-up. This data was complemented with HIV-1 pol sequences from countries with a high burden of F1 infections or a potential role in the global origin of sub-subtype F1. The molecular epidemiology of the Belgian subtype F1 epidemic was investigated using Bayesian phylogenetic inference and transmission dynamics were characterized based on birth-death models. F1 sequences were retained from 297 patients diagnosed and linked to care in Belgium between 1988 and 2015. Phylogenetic inference indicated that among the 297 Belgian F1 sequences, 191 belonged to a monophyletic group that mainly contained sequences from people likely infected in Belgium, diagnosed in Flanders at a recent stage of infection and declared to be MSM. Together with a Spanish clade, this Belgian clade was embedded in the genetic diversity of Brazilian subtype F1 strains and most probably emerged after one or only a few migration events from Brazil to the European continent before 2002. The origin of the Belgian outbreak was dated back to 2002 and birth-death models suggested that its extensive growth had been controlled by 2012, coinciding with a time period where delay in antiretroviral treatment initiation substantially declined. In conclusion, phylogenetic reconstruction of the Belgian HIV-1 sub-subtype F1 epidemic illustrates the introduction and substantial dissemination of viral strains in a geographically restricted risk group that was most likely controlled by effective treatment as prevention.




Prof. Dr.  Kristel Van Laethem was trained as a biochemical engineer and holds a PhD in Medical Sciences from the KU Leuven since 2001. Currently, she is professor at the laboratory of Clinical and Epidemiological Virology at the Rega Institute of Medical Research and she is a lecturer at the KU Leuven. She is responsible for HIV-1 and HCV drug resistance testing in clinical practice at the University Hospitals. Her main research interests are epidemiology, resistance development, therapy and host response in HIV and HCV infections. She has over 120 publications in high impact journals.