Immunogenic bacterial vesicles with outer membrane proteins

摘要

Knockout of the mltA gene gives bacteria that spontaneously release vesicles that are rich in immunogenic outer membrane proteins and that can elicit cross-protective antibody responses with higher bactericidal titres than OMVs prepared by normal production processes. Thus the invention provides a bacterium, such as an E.coli, having a knockout mutation of its mltA gene. The invention also provides a Escherichia bacterium, wherein the bacterium: (i) has a cell wall that includes peptidoglycan; and (ii) does not express a protein having the lytic transglycosylase activity of MItA protein. Tol-Pal knockouts of pathogenic E.coli are also disclosed. The invention also provides compositions comprising vesicles that, during culture of bacteria of the invention, are released into the culture medium.