A10 Presence and frequency of M184V mutation in the MOBIDIP trial

The MOBIDIP trial evaluated the simplification by protease (PI/r) monotherapy for HIV infection versus dual therapy and boosted protease inhibitor plus lamivudine (PI/r + 3TC) in controlled patients under second-line regimens. MOBIDIP was interrupted because of a significant number of patients with virological failure (VF) at week 48 (W48) in PI/r (33/133, ∼25%) versus in PI/r + 3TC (4/132, ∼3%). At the time of first-line VF, 96 per cent of patients harbored the M184V mutation. The presence of the M184V mutation was related to a protective effect against VF in the PI/r + 3TC arm. We developed a methodology that allows to determine the frequency of M184V/I mutations in the HIV reverse transcriptase (RT) gene in peripheral blood mononuclear cells (PBMC) obtained before MOBIDIP simplification. Paired-end sequences were obtained from 252 PBMC samples covering the first 855 bp of the RT gene (HXB2: 2485–3405) by MiSeq technology. These sequences were subjected to an in-house Bioinformatics pipeline. The results of our pipeline were compared to the output of PASeq (https://www.paseq.org), an open web-tool for the identification of drug resistance mutations. The M184V mutation was identified at a frequency greater than 1 per cent in 178 individuals (∼71%). The M184I mutation was observed in 34 patients (∼13%), always in the presence of stop codons, and is in agreement with expectations, as this mutation is a known APOBEC-targeted site. Sixty-seven patients (∼27%) had a frequency of the M184V mutation with values greater than 75 per cent. PASeq confirmed the presence of M184V mutation in 173 patients. The frequencies estimated by the PASeq tool and in-house pipeline were correlated up to 99.5 per cent. We found a significant loss of the M184V mutation archived in PBMC between the first-line regimen treatment failure and the beginning of the MOBIDIP trial. In patients under long-term antiretroviral therapy, as in our case, viral sub-populations could be lost, reducing the presence, and frequency of a mutation. In the next step, we will evaluate the association between the presence and frequency of M184V mutation and MOBIDIP results.