Subtype and genotypic resistance analysis of HIV-1 infected patients in Austria

Analysis of HIV-1 subtypes and genotypic resistance have been shown to be relevant for epidemiologic and therapeutic studies or for vaccine development. In Europe, the majority of HIV-1 isolates belong to subtype B. Due to migration an increasing incidence for additional subtypes and complex recombinant forms are expected.

To evaluate the prevalence of HIV-1 subtypes in Austria, 188 plasma samples of treatment experienced patients were investigated. For phylogenetic analysis protease and reverse transcriptase genes were amplified and sequenced. Subtypes were determined by comparing reference sequences. For genotypic resistance determination, the Resistance-Algorithm-Comparison from Stanford University was used.

Non-B subtypes were found in 20.2% of all patients with a dominant prevalence (50%) in the Southern provinces of Austria. With 85% CRF01_AE and CRF02_AG are the predominant circulating recombinant forms in Austria. When resistance mutations were analyzed, 57.4% of all patients were susceptible to all three groups of antiretroviral drugs, whereas in 12.2% resistance against all three classes of antiretroviral drugs was found.

HIV-1 subtype B is still dominant in major parts of Austria. However, a significantly increasing percentage of non-B subtypes and recombinant forms are observed in the Southern provinces.