Sook Yin Chong Shi Qian Lew Tauqeer Alam Christopher Gaulke Gee W Lau ^*

• University of Illinois at Urbana-Champaign, Champaign, United States

The Streptococcus pneumoniae (pneumococcus) quorum sensing system, the competence regulon, is well-known to regulate genetic transformation but is also crucial for virulence. Some pneumococcal strains are able to enter a transient competent state for genetic transformation in an optimized competence-inducing medium when the threshold level of the peptide pheromone competence stimulating peptide is attained; upregulating the expression of three distinct phases of "early", "late" and "delayed" competence genes. However, mechanisms driving competence development during host infection are rarely examined. Recently, we discovered that pneumococcus can enter a prolonged and persistent competent state naturally during acute pneumonia in mice, and through RNA-Seq, we revealed that both early and late competence genes were profoundly expressed throughout the entire course of pneumoniaderived sepsis. In the present study, we conducted a comparative analysis of pneumococcal competence development in vitro and in vivo during pneumonia-derived sepsis. This analysis involved examining existing RNA-Seq data and validating it using RNA obtained from an independent replicate experiment. We found that there were significant differences in the competence development between in vitro culture conditions versus during pneumonia-derived sepsis.