Fig 2. Infection rates of RRR-to-KKK V3 loop mutants.

(a) Blue stained TZM-bl cells that had been infected by RRR, RKR and KKK mutants of viruses NL-952.1, NL-952.2 and NL-952.3. For each experiment, about 10⁴ cells/96-well were infected with cell culture supernatants containing virus equal to 0,5 ng p24. Staining with X-gal was carried out two days post infection. (b) Viruses containing the amino acid combinations as shown in Table 1 at the V3 loop positions 9-to-11 were tested for infectivity using CD4+, CCR5+ and CXCR4+ TZM-bl cells. Shown are the means and standard deviations based on ten experiments. Virus inocula were standardized based on p24 antigen measurements (0,5 ng p24/10⁴ cells/96-well). Within the set of RRR-to-KKK mutants, all RRR-virus mutants (black bars) showed the highest and the KKK-virus mutants (red bars) the lowest infection rates.