Proviral genome structures of various HIV-1mt clones. HIV-1 NL4-3 (32), SIVmac239 MA239 (71), and SIVgsn166 (GenBank accession number AF468659) sequences are indicated by white, black, and red areas, respectively. Green arrows show adaptive mutations that enhance viral growth potential (47). Orange arrows show the CA-Q110D mutation that augments viral growth in macaque cells/monkeys (19, 24). Blue arrows indicate CA substitutions (M94L/R98S/G114Q) identified in this study that are responsible for viral growth enhancement. H6/7L, loop between helices 6 and 7 in Gag-CA.