Structure-activity relationship study of the substituent at position 5 of the thienyl core in MUT-A series. Shown are activities of racemic MUT-A and analogs with various modifications on the chemical group at position 5 of the thiophene core on IN T124/T125 and A124/A125 variant in biochemical interaction assays and multiple-round and single-round infection assays. Means are from at least three experiments (standard deviation omitted for clarity). The two compounds with better susceptibility of IN AA (fold-change closest to 1) are boxed. a, IC50 or EC50 fold-change AA/TT. b, for IN multimerization, the fold-change takes the AC50 and plateau shifts into account, according to Equation 1. nt, not tested; nr, not reliable (marginal effect).