HDAC9 and infection: The hemolysin known as listeriolysin O (LLO) has previously been shown to inhibit histone acetylation and phosphorylation in human epithelial cells infected with L. monocytogenes[26,27], whereas prolonged exposure to LPS and infection with pathogenic Mycobacterium tuberculosis strains causes the transcriptional induction of multiple HDAC genes in mammals [28].