Project description:Investigation of whole genome gene expression differences between a full (four-gene) SlrV locus 1 deletion compared to the WT PittII strain. Removal of the four SlrV genes (aka macrophage survival factors : Δmsf) results in a competetive defect with the WT strain in in vitro biofilms and in the otitis media chinchilla model. It also results in an inability to persist within macrophages long-term in vitro and to escape from the middle-ear space and infect other sites in the chinchilla model.
Project description:Non-typeable Haemophilus influenzae (NTHi) contains an N6-adenine DNA-methyltransferase (ModA), that is subject to phase variable expression (random ON/OFF switching). Five modA alleles, modA2, 4, 5, 9 and 10, account for over two-thirds of clinical otitis media isolates surveyed. Single Molecule Real Time (SMRT) methylome analysis identified the DNA recognition motifs for all five of these modA alleles. Phase variation of these alleles regulated multiple proteins, including vaccine candidates. ON/OFF switching of modA alleles resulted in differential regulation of key virulence phenotypes, such as antibiotic resistance (modA2, 5, 10), biofilm formation (modA2) and immunoevasion (modA4). Analysis of the modA2 strain, 723, in the chinchilla model of otitis media showed a clear selection for switching from modA2OFF to ON in the middle ear. This is the first report of a biphasic epigenetic switch controlling bacterial virulence, immunoevasion and niche adaptation in an animal model system
