Establishment Of Infection Models Of Edwardsiella Tarda In Mouse And Mouse-originated Cells

Although Edwardsiella tarda is a kind of important fish pathogen, it can also infect higher vertebrates such as reptiles, birds, mammals and even human. So, developing a mouse model for E. tarda infection is very important. It can help us not only deeply explore the interaction between pathogen and host but also develop the more effective vaccine and medicine against E. tarda. At the same time, there is a relatively high similarity between fish and mammals immune system. With the mouse infection model, some immune mechanism problems can be calrified that can not be worked out in a fish model because of some technical shortcomings, and more experiment methods can be used to study the interactions between pathogens and host.In this work, we first developed a mouse model for wild E. tarda EIB202infection and explored the morbidity, LD50, symptoms of disease and bacterial burden change under different route of infection. The result indicated that EIB202could successfully infect mouse and make it sickness and even dead. On the basis of this mouse infection model, a preliminary investigation was also made about the infection of TTSS and T6SS mutant strains. Either TTSS or T6SS was demonstrated to be a key pathogenic factor for bacteria infection in mouse. In addition, the methods of isolation and in vitro culture of primary cells from mouse were established, such as the bone marrow derived macrophages (BMDMs), polymorphonuclear leukocyte (PMNs), and epithelial cells of different tissues, and EIB202infection in these cells was investigated. It was found that EIB202could stimulate BMDMs to produce inflammasome and pyroptosis. In the early time, EIB202could be effectively restrained or killed by PMNs but its pathogenicity was significantly enhanced in primary epithelial cells of mouse organs when released by macrophages.We successfully established infection models of E. tarda in mouse and related cells, which made a basis for the deeply research about interaction mechanisms between pathogen and host.