Triple Class HIV-1 Drug Resistance in Croatia: the First Report

Resistance of Human Immunodeficiency Virus (HIV) to antiretroviral drugs is an important limitation in achieving complete suppression of viral replication and therefore represents an important clinical issue. It refers especially to therapy-naive individuals infected with resistant HIV strains, e.g. individuals with transmitted drug resistance (TDR). Transmitted drug resistance mutations (TDRMs) are clinically relevant and may reduce the efficacy of antiretroviral therapy. In this paper, we report the first case of HIV-1 transmitted triple-class drug resistance in Croatia. The aim of this study was to characterize drug resistance patterns and TDRMs in the newly diagnosed, treatment-naive HIV-1 patient with such a complex resistance pattern. Sanger sequencing (SS) of the sample showed four reverse transcriptase inhibitor (RTI) resistance mutations (E44D, T215E, K103N, L100I) affecting two drug classes and two protease inhibitor resistance mutations (V32I, I47V). To characterize HIV-1 minority drug resistance variants below the detection limit of SS, deep sequencing (DS) analysis was performed. DS analysis identified the same triple class resistance pattern that was identified by SS with addition of several other RTI mutations. The patient described in this report is the first patient with HIV-1 triple-class resistance in Croatia and further studies will be directed toward analysing possible local onward transmission of this resistant virus.