Studies On Relationship Between Some Biological Characteristics And Pathogenesis Of Escherichia Coli Isolated From Swine In Tianjin Aera

Studies on relationship between some biological characteristics and pathogenesis of forty-eight Escherichia coli (E.coli) isolated from swine in Tianjin aera, including biological chemistry, pathogenicity, O serogroup, drug-resistance, hemolysis, corgo red (CR), haemagglutination (HA), D-mannose resistance haemagglutination (MRHA). The result showed that the pathogenesis of E.coli was no relevant to O serogroup and CR, but was positive relevant to drug-resistance, hemolysia and HA.The sixteen E.coli strains of seven predominant O serogroups were resolved by ultrasonics, and the out membrane proteins (OMP) of these strains were prepared with improved N-lauroylsarosine method and analyzed by SDS-PAGE. SDS-PAGE analysis showed that OMP-1 was found from Oio, 021, 093, Oiog, Oog and OH? isolates; OMP-2 was gained from Oao and 693 isolates; OMP-3 was received from Oil and OHI isolates. The result showed that the strains of same O serogroup have the different OMP patterns, and the strains of differient O serogroups have the same OMP pattern. Because the OMP could reflect the genetic correlativity of E.coli strains, according to the variant of OMP patterns, we can rice the strains and made it become recombinant vaccine for prevent and control the disease more easily and rapidly. The experiment did some basic researches for it.The DNA analysis of plasmids for sixteen E.coli strains were performed by fingerprinting. The comparision of plasmids among strains demonstrated that the strains derived from the same source exhibited the identical or similar profiles and those from different sources exhibited the distinct profiles. Plasmid's DNA cleaved with EcoR Ifurther proved this result. The plasmids of large molecular weight were in the high-pathogenicity strains, not in the low-pathogenicity strains. So we can concluded the locus of virulent genes were the large plasmids. The quantities of ribbon in high-pathogencity strains were more than low-pathogenicity strains. The comparison of plasmid patterns and drug resistance patterns demonstrted that the former remains more stable than the latter. The O serogroup of the E.coli was no relevant to plasmid's patterns. The technology of plasmid profile analysis not only has advantages in molecular epidemiologic investigation, but also provides the basis of theory and experiment for the new vaccine preparation. This is a new way to protect swine for E.coli diseases.