Relative replicative fitness of the dual tropic C19 and C27 HIV-1 when competed against reference strains on PBMCs. a The dual tropic HIV-1 isolates, C19 and C27 were competed against the x4 reference strains, A8 and E6 on PBMC using equal MOIs (0.004) of each virus tittered on U87.CD4.CXCR4 cells or PBMCs (same donor and blood draw as those used in competition). b A similar set of competitions on PBMCs involved the same dm viruses competed against the r5 reference strains, B2 and C3 using equal MOIs tittered on U87.CD4.CCR5 cells or PBMCs. Fitness difference (or ratio) is shown with all competitions where the relative fitness of the dual tropic HIV-1 isolate is plotted as a ratio to the relative fitness of the reference virus in the competition. The titers of all dual tropic and reference HIV-1 isolates are shown in Additional file 1: Table S1.