Subtype variability, virological response and drug resistance assessed on dried blood spots collected from HIV patients on antiretroviral therapy in Angola.

BACKGROUND Subtype variability may influence treatment response and selection of drug resistance mutations in HIV-positive patients on antiretroviral therapy. PATIENTS AND METHODS A retrospective study was performed on specimens collected on dried blood spots (DBS) from HIV-positive individuals receiving antiretroviral therapy in Luanda, Angola. HIV-RNA, drug resistance mutations and subtypes were examined in 294 HIV-positive patients treated with two nucleoside analogues (NA) plus one non-nucleoside reverse transcriptase inhibitor (NNRTI). RESULTS Overall, 217 (74%) had <1000 HIV-RNA copies/mL after a median of 12 months (range 7-24) of therapy. CD4 count was significantly higher in subjects with undetectable viraemia compared with viraemic patients (294 versus 220 cells/mm3; P = 0.003). Reverse transcriptase and/or gp41 genes could be genotyped in only 45 (58%) of viraemic patients, probably due to poor storage conditions of DBS. The most frequent resistance mutations were M184V (70%) and K103N (39%); 65% had mutations conferring resistance to both NA and NNRTI. Only five patients did not show resistance mutations. A wide HIV-1 subtype heterogeneity was found: 6 C (18.2%), 2 F (6%), 2 H (6%), 1 D (3%), 1 G (3%), 8 CRF02_AG (24.2%), 2 CRF06 (6%), 1 CRF01_AE (3%), 1 CRF14_BG (3%), 1 CRF25 (3%) and 1 CRF19 (3%). HIV clade could not be assigned in 7 (21%). CONCLUSIONS Nearly three-quarters of HIV-positive individuals who began an NNRTI-based triple regimen in Angola showed undetectable viraemia after a median of 12 months of therapy, a rate similar to that reported in Western countries. Specimens collected on DBS may allow monitoring of treatment response in resource-limited regions, although adequate temperature and humidity storage conditions are important to ensure RNA stability and further successful testing.