Figure 6.

Flow chart for prediction of HIV-1 coreceptor selectivity based on V3 loop sequence and charge properties. This scheme is based on the presence of the N⁶X⁷T⁸|S⁸X⁹ sequence/glycosylation motif [71], the presence of a positive amino acid at sequence positions 11, 24, and 25 (the 11/24/25 rule) [12], and the net charge. The presence of acidic chemical groups in the glycosylation patterns (e.g., sialic acids) could affect the charge of the V3 loop, thus affecting the coreceptor selection. Therefore, the virus can use CXCR4, CCR5 or both receptors for cell entry (dual tropic).