Non-typeable Haemophilus influenzae (NTHi) is a common bacteria found in the human nasopharynx. NTHi is responsible for multiple upper and lower respiratory tract infections, and is a significant global healthcare burden. The genotypic and phenotypic diversity of NTHi results in very few strains presenting identical protein profiles. Therefore, picking conserved protein antigens that are present in all strains, and do not show variable expression is key to designing better anti-NTHi therapeutics. MsrAB is a protein which repairs bacterial proteins that have been damaged by oxidative stress, a key method that the host immune system uses to kill bacteria. Although MsrAB is annotated as a periplasmic protein, it has been reported to repair outer-membrane and outer-surface proteins in NTHi. MsrAB is part of the core NTHi genome and shows high sequence conservation. In other small genome bacterial pathogens, such as the pathogenic Neisseria, it has been demonstrated that MsrAB is located on the bacterial cell surface.
This study will investigate if the MsrAB from NTHi is located on the bacterial surface using a number of key experiments. MsrAB specific antisera will be raised to allow Western blotting of periplasmic and outer-membrane enriched cellular fractions; whole-cell ELISAs will determine if MsrAB is surface located; MsrAB will be affinity tagged in NTHi and tag specific anti-sera used to determine the cellular location of MsrAB.
The results of the study will confirm the precise location of MsrAB in NTHi, and determine if this protein is suitable for development as a novel therapeutic target.