Technology for inferring co-receptor usage in HIV-1. PLoS ONE 9, e99508 (2014). 11. Kagan, R. M. et al. A genotypic test for HIV-1 tropism combining Sanger sequencing with ultradeep sequencing predicts virologic response in treatment-experienced patients. PLoS ONE 7, e46334 (2012). 12. Gibson, R. M. et al. Sensitive deep-sequencing-based HIV-1 genotyping assay to simultaneously determine susceptib