A Comparative Study About Four Strains Of Shigella Sonnei

Shigella spp. is a kind of food-borne bacteria that can cause typical diarrhea symptoms for patient (fever, abdominal pain, diarrhea) by invading intestinal epithet-lium cells. Shigella sonnei is one of the main pathogenic bacteria. As a result of the difference of environ-ment, Shigella sonnei shows a lot of difference. Through comparative studies of four strains Shigella sonnei (S09071,S09072,S09076,S09077) that from different areas, This topic provides some guiding significance for dysentery's clinical epidemic prevent-ion and epidemiology of research. By constructing a library of large fragment of virulence plasmid deletion mutants, we can be easily to research interaction between virulence plasmid and chromosome, also lay the foundation for researching of shigella pathogenesis.In this paper, firstly we made a detailed comparative study by morphology, Agglutinate experiment, virulence evaluation, the growth curve determineation, physiological biochemical tests, drug sensitive test and proteomics for shigella sonnei S09071, S09072, S09076, and S09077. Then we tried to establish a Knocking-out method of large fragment of virulence plasmid of shigella spp.. According to these researches, we made the following results:(1) Shigella sonnei is straight rods, and surface of thallus is uneven. It has not spore, capsule, flagellum, and pilus. Size is about 0.5～0.7 x 1-2 um. Watching form LB solid medium, we can see colonies is a larger circle, smooth, wet, milky white, translucent, neat edge, size about 2.5 mm. Four strains are very similar from the morphology.(2)S09071 is growing fastest, and S09076, S09077 is lower-growing, S09072 is the lowest.(3)S09076,S09077 can metabolize rhamnose, L-rock sugar, bearberry glucoside, esculin, but S09071, S09072 cannot metabolize it. (4)S09071, S09072 is more stubborn drug-resistant bacteria than S09076, S09077, among S09072 is most stubborn.(5)S09072 is a virulence strain and S09071, S09076, S09077 are avirulent.(6)According to detection of virulence genes, we found S09071, S09076, S09077 had lost part of the virulence genes. While the tested genes of S09072 could be detected.(7) S09071 and S09072 have similar biochemical characteristics and protein expression profiles. So do S09076 and S09077. However, between the former two strains and the latter two strains, there are forty-eight differences which can be presented by two-dimensional electrophoresis.47 protein spots were identified by MALDI-TOF/TOF, representing a total of 43 proteins, including GadA, GadB, OmpA, TatB, etc.These protein play an important role in bacterial metabolism and adapting to different environment.(8) A library of virulence plasmid deletion mutants could be constructed through gradually deleting large fragments (20-30kbp) of the virulence plasmid of Shigella spp. It laid a foundation for researching the function of virulence plasmid and pathogenic mechanism of Shigella spp..