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Abstract:

Introduction: The study of local HIV-1 epidemics is essential to formulate tailored prevention policies. Herein, we aimed to determine the prevalence of subtypes, transmitted drug resistance (TDR) and the factors that may have led to the self-sustainment of the HIV-1 infection in Cyprus.   Materials and Methods:  335 HIV-1-infected patients from the Cyprus Reference AIDS Clinic, Larnaca National Hospital diagnosed between 2003 and 2012 were included in this study. HIV-1 pol sequences were subtyped with REGAv3, COMETv1.0 and manual phylogenetic analysis. TDR was evaluated in 204 naive patients according to the WHO-2009 surveillance list. To determine transmission clusters (TC), maximum likelihood trees were constructed for the most prevalent subtypes with four additional control datasets retrieved from public and private databases. TC were identified according to a genetic distance of <0.045 and 98% bootstrap support. Logistic regression was used to evaluate factors associated with TC. Results:  70% of the population originated in Cyprus and 49% were men who have sex with men (MSM). The overall TDR prevalence was 2.9% (95% confidence interval (CI): 1.2-6.4). Resistance to nucleoside reverse transcriptase inhibitors (NRTI), non-NRTI, and protease inhibitors was 1% (CI: 0.04-3.7) each. The most prevalent subtypes - B (54%), A1 (20%), C (9%), CRF02_AG (6%) and F1 (6%) - were included in the TC analyses. 47 TC were identified, of which 20 had a size > 2. 31% of the Cypriot patients (96/307) were included in TCs, 75% were male, 57% were between 25 and 45 years old, 51% were MSM, 41% were living in Nicosia and 45% reported being infected in Cyprus. For subtype B, 54% of the patients were in TCs while only 25% for subtype A1. The single factor associated with being in a TC was age between 25 and 45 years in the multivariate analyses. Conclusions: TDR prevalence in Cyprus remains low. Onward transmission of HIV-1 is significantly associated with young adults, who should be more effectively targeted by prevention policies.