Background
Non-group M HIV-1 (O, N, and P) are known as genetically divergent and mainly found in Cameroon. Due to the prevalent Y181C mutation in 75% of non-M strains, current treatment guidelines has not recommended the use of Non-Nucleoside Reverse Transcriptase Inhibitors. However, the specific resistance profile of Doravirine (DOR) challenges this recommendation.
The DORAVI-O study aims to assess the phenotypic sensitivity of non-M HIV-1 clinical isolates to DOR and explore potential genotypic patterns associated with resistance.
Methods
Twenty eight HIV-1 non-M clinical isolates (26 O, 1 N, 1 P) were tested. Two millions human mononuclear cells from healthy donors were infected with 100 TCID50 of viral supernatant for 2 h and exposed to 5 concentrations of DOR (0.1 to 1,000 nM) in quadruplicates at 37°C with 5% CO2 for 3 to 4 days. Viral RNA was extracted (EZ1 Qiagen) and analyzed by qRT-PCR to determine the inhibitory concentration 50 (IC50), maximum percentage inhibition (MPI) and Fold Change (FC). Sanger sequencing (CEQ8000 Beckman) of RT region was performed and sequences compared with the updated french ANRS resistance algorithm.
Results
The DOR phenotype was identified in 34% yield on the whole panel, according to internal standardization procedures. Of the 28 exploitable phenotypes 3 isolates (2 O, 1 P) exhibited IC50s>100,000 nM and 4 HIV-1/O had IC50s between [1,000; 10,000 nM], with FC > 100. For the remaining 21 isolates (0 < FC < 50), the mean and median IC50s (+-SD) were 133 nM and 37.4 nM (+- 181 nM) respectively, with IC50s ranging from 0.204 nM to 597 nM. The mean and median MPI were 79.25% and 78.73% respectively. Resistant strains generally displayed lower MPIs, like RBF168, P isolate (MPI 34.4%; IC50 > 100,000 nM) but except for BCF008 (IC50 1260 nM; MPI 90.4%). Most of the panel was classified as DOR intermediate sensitivity (french ANRS algorithm) due to A98G (96%) and Y181C (75%). However, resistant strains (IC50s > 100,000 nM), showed conflicting genotypic interpretations: RBF168 was genotypically sensitive while BCF108 was considered resistant (A98G, Y181C, G190A, and H221Y pattern).
Conclusions
The DORAVI-O study revealed a broad phenotypic sensitivities of non-M HIV-1 to DOR, despite the natural Y181C mutation. Phenotypic resistance was observed in 6O, 1P (25%) whereas only 1O isolate has resistance mutations to DOR, suggesting the potential existence of non-M virus specific genotypic pattern not covered by the french ANRS algorithm designed for M variants.