Figure 5.

(A) Schematic drawing of the envelope region of CB11D and HXB2RU3. CB11D contains the KpnI-BsmI fragment (amino acids 42 to 612) of a primary isolate, CB11D.v, in the backbone of molecular clone HXB2RU3. Also shown are the V3 sequences of the CB11D and mutants, which had different type of amino acid substitutions introduced to the Arg-298. (B) Positively charged residue at position 298 is critical for CCR5 utilization by primary virus CB11D. Equal amounts of CB11D and mutant viruses, as standardized by p24, were used to infect HOS-CD4 cells expressing pBABE-puro (vector control), CCR5 or CXCR4. The p24 level of culture supernatants at day 7 were shown.