One of the viruses with the DTQ mutations, KM217855, was reported as a transmission founder virus for the MSM outbreak in China, but the other founder viruses appear not to have harbored the DTQ mutations.36 Those results, in combination with the infection assays described in this study, indicate that resistance to MxB and human TRIM5α is not essential for transmission of HIV-1. Here, MX2 is linked to infection.