The observation that GL8-like and B14-like viruses differ in the way they interact with the viral receptors CD134 and CXCR4 is consistent with findings that have revealed that HIV-1 clade B envelopes from early infection tend to harbour amino acid signatures that favour efficient Env expression in infected cells, enhancing Env incorporation into nascent virions and replication to higher titres [51], [52]. This evidence concerns the gene CXCR4 and infection.