Study On Escherichia Coli Outer Membrane Protein OmpW Resisting Innate Immunity

Bacteria is divided into Gram-positive bacterium(G+) and Gram-negative bacterium(G-)by Gram staining. The ectotheca of G+is made up of peptidoglycan with little protein. Butthe ectotheca of G-is quite complexity. It included periplasmic space and outer membraneexcept plasma membrane. Many large-scale infectious diseases caused by G-in history.Innate immunity is an important defense mechanisms for people and animals to resistmicrobial infection. It includes the barrier of skin, mucosa and placenta; the phagocytosis ofphagocyte; complement in blood serum to kill microbe. At the same time, the survival bacteriain vivo after long-term selection evolution will produce a new way to resist innate immunity. Inrecent years, people have done much research on bacterial outer membrane.They found theouter membrane protein of G-can resist human innate immunity.The outer membrane protein OmpW widely existed in G-. It composed of eight β-strands,forming a long narrow hydrophobic channel. OmpW involved in bacterial drug resistance, theconcentration of salt tolerance, and the expression of OmpW was related with diseases, such asinflammatory bowel disease, reactive arthritis. Thus, OmpW in bacteria played an important role inresisting various adverse environment. Therefore, by Red recombinant system I constructedEscherichia coli OmpW knockout bacteria(Δ OmpW). By comparing of parent bacteria K12andΔ OmpW in anti-phagocytic activity by macrophage and anti-bactericidal effect by complementstudyed the role of OmpW in resisting congenital immunity.The experiment in vivo and vitro, ΔOmpW was easier phagocytosed by macrophage andkilled by complement. We extracted membrane protein of parent bacteria and survival bacteria inmacrophage, through SDS-PAGE we analysed to find out the expression of OmpW isincreasing. Therefore we thought OmpW played an important role in innate immunity. Mouseactive protection experiment was performed by mice immunized with OmpW. Then we injectedbacteria to immunized mouse and un-immunized mouse. The results showed that immunizedmice survived, un-immunized mice were killed. This included that the OmpW antibody can protect mice against bacterial infection. In another view it reflected the importance of OmpWfor resisting the host immune.This study revealed that OmpW played an important role in resisting innate immune.It layed a foundation for further researching on the mechanism of OmpW in resistingphagocytosis and resisting complement. And it also played a practice significance for controlingand treating the infectious diseases.