Fig. 2.

In vitro mid-logarithmic phase transcriptional microarray analysis of covRS intact and covRS mutant non-M1 GAS. a log₁₀-fold differential expression of virulence-associated and regulatory genes of the covS mutants 5448AP (filled circles), A20 (open circles) and NS88.2 (shaded circles) compared to the covRS intact M1T1 strain 5448. Selected genes are significantly differentially expressed in 5448AP with respect to 5448 (p < 0.05). b Principal component analysis on the non-M1 isolates ALAB49 (M53) and NS730 (M90), NS88.2 (M98.1) and A20 (M23), in addition to the M1T1 reference strains 5448 and 5448AP, revealed 2 distinct expression profiles in this 6-isolate strain set. Solid-line boxes placed in the plot area highlight strain clusters. The dashed-line box highlights the M1T1 strains 5448 and 5448AP, which, apart from a single base insertion in the 5448AP covS gene, harbor identical genomes.