VIP analysis from pairwise PLS-DA modeling of (A) mutant III-4 with M129, mutant IV-22 with M129, and mutant III-4 with mutant IV-22, or (B) diverse clinical isolates relative to the genotype 1 reference strain M129. Orange, major band wavenumbers in common for VIP analysis of wild-type M129 and either mutant (A) and also from the genotype VIP analysis (B); green, major band wavenumbers in common for VIP analysis of wild-type M129 and either mutant, as well as VIP analysis of the two mutants (A) and also for the genotype VIP analysis (B).