Utility of HIV-1 DNA genotype in determining antiretroviral resistance in patients with low or undetectable HIV RNA viral loads

Abstract

Objectives: To investigate the extent to which drug resistance can be evaluated from proviral HIV-1 DNA genotype compared with RNA genotype at different timepoints. Patients and methods: In HIV-1-infected patients routinely seen at a university hospital, who needed to change their current ART, antiretroviral drug resistance was determined from DNA genotype and was compared with past RNA genotype (group 1) or same-day RNA genotype (group 2). A ‘resistance sum’ was defined as the sum of agents to which resistance was present and was calculated across NRTI, NNRTI and PI. We defined ‘loss of information’ as when a lower resistance sum was observed in DNA than in RNA samples. Results: Of the 74 and 26 patients included in groups 1 and 2, respectively, most had a long median duration of known HIV-1 infection (17.4 and 14.2 years) and ART (15.3 years and 13.5 years). For group 1, the median (range) resistance sums between DNA/RNA were 0 (0–6)/1 (0–6) for NRTIs, 0 (0–4)/0 (0–4) for NNRTIs and 0 (0–7)/0 (0–8) for PIs, which were comparable with group 2. Loss of information in DNA was substantial for group 1 (37.8%) and less so for group 2 (11.1%). In multivariable analysis, only longer ART duration was significantly associated with loss of information. Results were similar in patients harbouring resistance to one or more agents. Conclusions: In a real-life setting, genotyping DNA from PBMC has some degree of concordance compared with RNA. Loss of information in DNA would appear to coincide with longer periods of ART.