F a CCR5-antagonist-based treatment4,5. Deep sequencing techniques can detect minor variants, especially ones that use CXCR46?. The 454 GS-Junior sequencing platform (Roche) can reliably predict HIV-1 tropism9?1. The Ion Torrent Personal Genome Machine has also been validated for tropism determination12. Another study evaluated the Illumina platform for determining HIV-1 drug resistance and HIV-1