Transcriptomic analysis of the major regulator of virulence CovR in Group B Streptococcus strains BM110 and NEM16.

To define the transcriptional response associated to a CovR inactivation we performed RNA-Seq in GBS strains BM110 and NEM316. We used mutants in which CovR is inactivated following a two base-pairs chromosomal substitution (AT->CC) resulting in the translation of a CovRD53A variant unable to be phosphorylated by the histidine kinase CovS. We also used a ?covR mutant in strain BM110 in which the covR sequence is deleted from the chromosome. Overall design: We have perfomed two experiments. Th first experiment includes the transcriptomes of BM110 and NEM316 wild-type and the correspondent CovRD53A mutant strains, whom cultures, RNA preparation and sequencing were done in parallel to allow a quantitative comparison. The second experiment includes the transcriptomes of BM110 wild-type and ?covR mutant. For both experiments, three triplicates were done for each sample and each replicate was done in a different day to take into account the replica biases during statistical analysis.