Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe

Transmitted human immunodeficiency virus drug resistance in Europe is stable at around 8%. The impact of baseline mutation patterns on susceptibility to antiretroviral drugs should be addressed using clinical guidelines. The impact on baseline susceptibility is largest for nonnucleoside reverse transcriptase inhibitors.

Background. Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001.

Methods. Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)–infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0.

Results. The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%–9.5%) in 2008–2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones.

Conclusions. Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected.

Distribution of HIV-1 subtypes circulating in Slovakia (2009-2012)

Slovakia is one of the European countries reporting a low prevalence of human immunodeficiency virus 1 (HIV-1) infection. The HIV-1 subtype B was previously the most prevalent in Slovakia and mostly associated with men having sex with men (MSM) (Habekova et al., 2010). The aim of this study was to determine the distribution of individual HIV-1 subtypes among the virus-positive individuals diagnosed in 2009-2012 in Slovakia and to compare these data with those from 2004-2008. The HIV-1 subtype B exhibited the highest prevalence (86.1%) and was mostly associated with MSM as stated before. HIV-1 non-B subtypes were found in 13.9% of patients, led by CRF01_AE (6.3%) and followed by subtype C (2.8%), F1 (1.4%), CRF03_AB (1.4%), G (0.7%), CRF02_AG (0.7%), and CRF12_BF (0.7%). The incidence of non-B subtypes varied in 2009-2012, showing a maximum in 2012. MSM represented the main risk group for total HIV-1 (68.1%) as well as B subtype (63.9%) infections in Slovakia. In contrast, the heterosexual contact represented the main route of HIV-1 acquisition of the non-B subtype virus infection. Together with the increase in the number of patients infected with the viruses of non-B subtype also other changes were observed: infections with the viruses of non-B subtype became more common among MSM and not so strongly associated with heterosexual contact. All these findings may help to design the right strategy for retaining of HIV epidemic in Slovakia at low level.

Genetic subtypes of HIV type 1 circulating in Slovakia

Slovakia belongs to the group of European countries with a low prevalence of HIV infection. The major proportion of HIV-positive cases in Slovakia is still represented by MSM, followed by heterosexuals infected through unprotected sexual intercourse. This study was conducted to update the description of HIV subtypes circulating in Slovakia. HIV-1 partial pol gene sequences from 143 individuals were prospectively collected from 2004 to 2008 and analyzed. Phylogenetic analysis based on HIV-1 partial pol gene sequences revealed the highest prevalence of HIV-1 B subtype (93.0 %), predominantly associated with the MSM group. Ten (7.0%) individuals were infected with HIV-1 non-B subtypes. The pure subtypes were more frequent (7; 4.9%) than CRFs (3; 2.1%) and their occurrence was as follows: subtype C (3; 2, 1%), subtype A (2; 1.4%), subtype F (2; 1.4%), CRF_01AE (1; 0.7%), CRF_02AG (1; 0.7%), and CRF08_BC (1; 0.7%). Data show slightly increasing HIV-1 subtype diversity, with HIV-1 subtype B still having the highest prevalence in the Slovak-infected population.