“…Five highly polymorphic mutations, R20K [ 50 ], I72V [ 9 , 33 , 51 ], L74I [ 7 , 23 , 24 , 25 , 26 ], S119P [ 51 , 52 ], and V201I [ 11 , 26 , 38 , 53 ], were frequently reported in regard to a small reduction in replication capacity relative to the wild type. It has been reported that in the absence of major mutations, all these polymorphic mutations had little, if any, effect on drug susceptibility in vitro, thus suggesting a secondary role for viral fitness rescue and increasing resistance.…”