Performance of plasma separation cards for HIV drug-resistance genotyping in a resource-limited setting: comparison with plasma samples.

BACKGROUND: HIV drug resistance (HIVDR) threatens the effectiveness of antiretroviral therapy (ART) programmes in low- and middle-income countries. The Cobas Plasma Separation Card (PSC) is a recently developed specimen collection tool with potential to expand access to HIVDR genotyping in remote settings. This study evaluates PSC performance for HIVDR genotyping compared with plasma. METHODS: Paired plasma and PSC specimens were selected from 250 people living with HIV (PLHIV) on ART ≥6 months with viral load (VL) ≥1000 copies/mL. HIVDR genotyping followed CDC Atlanta in-house protocol; resistance interpretation used the Stanford HIVdb algorithm. Paired sequences were compared for subtype, nucleotide similarity, mutation profile and drug-resistance classification. RESULTS: Twenty paired specimens met inclusion criteria. Amplification of the HIV-1 Pol gene succeeded in 19/20 (95%) PSC samples. Of 19 paired sequences, nucleotide similarity was 98.5% (IQR 98.0%-99.3%). Eleven plasma samples showed 37 major drug-resistance mutations (MDM); 35 (94.6%) concordant MDM were identified in PSC. Discordances in four pairs were limited to mixed versus single bases and did not alter drug-resistance classification. Only one pair showed a clinically significant discordance (K103N detected in plasma but not initially in PSC). CONCLUSIONS: PSC demonstrated good concordance with plasma for HIVDR genotyping and has potential as an alternative specimen type for clinical practice and surveillance in resource-limited settings.