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/mm(3); 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.