Genomic comparisons of paired group A Streptococcus isolates

We performed a study in which the RD2 pathogenicity island was introduced into three group A Streptococcus (GAS) isolates (representative serotype M1, M49, and M59 isolates). To ensure that the only genetic difference between the paired parental isolates and the RD2-containing derivatives we performed a whole-genome sequencing comparison between each strain pair. Finding that RD2 is the only difference within each strain pair is of importance if we wish to assign any phenotypic difference between the isolates to the presence/absence of RD2.