Advances of Researches on Anti-phage Mechanisms of Host / 病毒学报

Phages also known as bacteria viruses, are recognized as the most abundant and diverse microbes. This diversity is adapting to the selective pressures such as the prevalence of the phage resistance mechanisms of bacteria. Phages invade and lyse bacterial through six steps (adsorption, injection, replication, transcription translation, assemble, release). Bacteria evolve to many anti-phage mechanisms to avoid phage infection and lysis. This paper focus on a variety of anti-phage mechanisms of bacteria.

Immune response to pT-ureB and pT-hpaA DNA vaccine in mice / 第三军医大学学报

Objective To investigate and compare the humoral immune response induced by eukaryotic expression plasmid pTCAEureB (pTureB)and pTCAEhpaA (pThpaA) injected intramuscularly in mice. Methods The ureB gene fragment was inserted into a eukaryotic expression vector pTCAE, and pTCAEureB was constructed. A total of 60 BALB/c mice were randomly assigned to be immunized by intramuscular injection of blank plasmid pTCAE, plasmid pTureB and pThpaA (n=20 in each group). Titers of specific IgG antibody in serum of each group were detected through ELISA respectively on week 2, 4, 6 after immunization. Results Specific IgG were observed in pTureB and pThpaA immunized groups and titers of antibody increased as time prolonged. IgG level was significantly higher in pT-ureB immunized group than in pT-hpaA group on week 6 after immunization. Conclusion Plasmid pT-ureB possesses good immunogenicity and induces a higher immune response than pT-hpaA.

Construction and identification of eukaryotic expression plasmid of hpaA of H.pylori / 第三军医大学学报

Objective To clone hpaA gene of H.pylori and construct its eukaryotic expression plasmid. Methods Gene hpaA amplificated from genome of H.pylori 11637 strain by PCR was subcloned into pMD18-T vector. Then hpaA cut down from the vector with restriction enzyme was inserted to pTCAE, and the product confirmed by restriction enzyme digestion and sequence was transformed to E.coli DH5?. pT-hpaA was transfected into CHO cell by electroporation, and HpaA protein was detected by Western blot. Results hpaA gene was inserted into pTCAE and the immunological reaction band with anti-HpaA serum at MW 30 000 was detected by Western blot. Conclusion Eukaryotic expression plasmid of hpaA of H.pylori is successfully constructed. Western blot analysis demonstrates that the expression of HpaA protein can be detected in culture supernatants of transfeced CHO cells, which lays the foundation for the further study.

Preparation and characterization of E.coli “bacterial ghost” / 解放军医学杂志

Objective To prepare the “bacterial ghost” of E.coli with heat-induction and analyse its lysis rate and configuration. Methods Through immediately shifting the culture temperature from 37℃ to 42℃, E.coli DH5? including plasmid pMuH36 was induced to lyse, and the OD value of culture media was measured every 30 minutes during the induction. After 4 hours of induction, the bacteria samples were collected to examine the lysis rate by CFU (colony formation unit) and the configuration of lysed bacteria was observed by transmission electron microscopy (TEM). Results The OD value of DH5? (pMuH36)began to decline after 1 hour of induction, and increased slowly after 4 hours of induction. The CFU assay showed that the lysis rate was about 95%. TEM observation proved that most of the lysed bacteria were emptied, whereas the whole outmembrane structure, i.e. “bacterial ghost”, remained. Conclusions The E.coli “bacterial ghost” was efficiently prepared and identified, which might provide the basis for further development of a more effective “bacterial ghost” vaccine and adjuvant.