SBi4211 alleviates gp120-induced central nervous system injury / 南方医科大学学报

OBJECTIVE@#To explore the protective effect of SBi4211 (heptamidine), an inhibitor of S100B, against central nervous system injury induced by HIV-1 envelope protein gp120.@*METHODS@#In an @*RESULTS@#In the cell co-culture system, SBi4211 treatment significantly inhibited gp120-induced expression of S100B, RAGE and GFAP in U251 cells (@*CONCLUSIONS@#SBi4211 can protect neurons from gp120-induced neurotoxicity possibly by inhibiting the S100B/ RAGE-mediated signaling pathway.

Constructing CXCR4 lentiviral vector and transfecting breast cancer cells / 实用医学杂志

Objective To construct lentivirus containing CXCR4 gene and transfect MCF-7 cells , and obtain CXCR4 high-expressing MCF-7 cells. Methods CXCR4 gene was amplified by RT-PCR to construct CXCR4/pSin-EF2, which was transfected into HEK293T cells with psPAX2 and pMD2G vector for lentivirus packing. Packaged lentivirus was used to transfect human breast cancer cells MCF-7, with empty lentivirus as control. CXCR4 mRNA and protein expression levels were detected by RT-PCR and Western blot before and after transfection. And flow cytometry was used to detecte cell surface CXCR4 expression. Results The recombinant plasmid CXCR4/pSin-EF2 was constructed successfully,identified by double digestion and sequencing, and transfected into HEK293T cells to obtain high-titer lentivirus. RT-PCR and Western blot confirmed that the expression of CXCR4 in MCF-7 cells increased significantly after CXCR4 lentivirus transfection. Flow cytometry results showed that the CXCR4 positive rate increased from 26.78% to 99.29%, while there is no significant difference in CXCR4 expression between vector-transfected MCF-7 cells and non-transfected MCF-7 cells. Conclusion CXCR4 lentivirus and the breast cancer cell line with high and stable expression of CXCR4 (MCF-7CXCR4) were successfully constructed.

Lactobacillus rhamnosus GG inhibits Cronobacter-induced meningitis in neonatal rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the inhibitory effect of Lactobacillus rhamnosus GG ( LGG) against Cronobacter-induced meningitis in neonatal rats.</p><p><b>METHODS</b>The cell adhesion and invasion capacities of Cronobacter were assayed in Caco-2 cells, and the optimal time length and concentration of the bacterium for infection were determined. The suppressive effects of LGG on the adhesion and invasion of Cronobacter in caco-2 cells were tested by competitive and exclusion experiments, and its inhibitory effect against Cronobacter-induced meningitis was evaluated in neonatal rats.</p><p><b>RESULTS</b>Cronobacter showed aggressive adhesion to caco-2 cells with an optimal infection time of 3 h. LGG produced a concentration-dependent inhibition of Cronobacter adhesion and invasion by competing with and excluding the latter for cell adhesion. In neonatal rats, LGG showed an obvious preventive effect and also a moderate therapeutic effect against Cronobacter-induced meningitis.</p><p><b>CONCLUSION</b>LGG can inhibit Cronobacter entry across the intestinal barrier to achieve preventive and therapeutic effects against Cronobacter-induced meningitis.</p>

Prokaryotic expression of Tir gene of enterohemorrhagic escherichia coli / 实用医学杂志

Objective To identify the immune activity of the recombinant protein Preli minarily after expressing Tir C-ter minal of enterohemorrhagic Escherichia coli(EHEC) in E.coli BL21/DE3 efficiently. Methods Tir C-ter minal (marked as Tir-C)was amplified by PCR considering the result of Bioinformatics analysis of Tir. The recombinant plasmid(designed as PET-30a(+)-Tir-C)was identified by PCR,sequencing and digested by restriction endonucleases. The positive recombinants were transformed into E.coli BL21/DE3 and induced by IPTG to express the Tir-C. The Tir-C protein was detected by SDS-PAGE and identify the antigenic of the recombinant protein Preli minarily by Western blot. Results The 675bp DNA was gained. The plasmid PET-30a (+)-Tir-C was built. Tir-C was expressed mainly in supernatant of lysis and was purified by Ni+affinity chromatograghy. Concentration of the purified protein is about 500 μg/mL and a unique band was detected with the relative molecular mass of approximately 24KDa by Western blot. Conclusion The recombinant Tir-C was expressed successfully and had immunoreactivity to some extent, which deserves the investigations for vaccine against EHEC.

Loop-mediated isothermal amplification for detecting enterohemorrhagic Escherichia coli O157:H7: a comparison with PCR / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a rapid method of loop-mediated isothermal amplification (LAMP) for detecting enterohemorrhagic Escherichia coli (EHEC) O157:H7.</p><p><b>METHODS</b>Six primers that specifically recognized the rfbE gene of EHEC O157:H7 were designed. Under the optimized reaction conditions, LAMP and PCR were evaluated for the sensitivity and specificity in the detection of 39 laboratory samples of EHEC O157:H7 strains, and their detection results of contaminated fresh pork samples were compared.</p><p><b>RESULTS</b>LAMP assay correctly identified all the 7 EHEC O157:H7 strains and showed negative results for all the 32 non-EHEC O157:H7 strains. The detection limit of LAMP was much lower than that of rfbE-PCR (10 vs 100 cfu/ml). In the detection of the contaminated pork samples, both LAMP and PCR yielded results consistent with those by the conventional detection method.</p><p><b>CONCLUSION</b>The rfbE-based LAMP assay can serve as a rapid, sensitive, specific and low-cost means for detecting EHEC O157:H7 strain.</p>

Construction of SDF-1P2G54, a specific antagonist of CXCR4 / 南方医科大学学报

<p><b>OBJECTIVE</b>To obtain a specific antagonist of CXCR4, SDF-1P2G54 by mutating SDF-1 second proline (P) into glycin (G) and removing the α-helix of its C-terminal.</p><p><b>METHODS</b>SDF-1p2g54 gene amplified by PCR was inserted into the vector pET-30a (+) and transformed into Escherichia coli (E. coli) strain BL21. After IPTG induction of E. coli, the expressed recombinant protein was purified with nickel-affinity chromatography column under denaturing conditions and refolded with gradient dilution and ultra-filtration. The chemotactic effect of SDF-1P2G54 on Jurkat cells and its antagonistic effect against SDF-1 were determined by transwell assay; flow cytometry was used to assay the ability of SDF-1P2G54 to induce calcium influx and CXCR4 internalization in MOLT4 cells.</p><p><b>RESULTS</b>The recombinant protein SDF-1P2G54 completely lost the functions to activate CXCR4 or to induce transmembrane migration of Jurkat cells and calcium influx in MOLT4 cells, but maintained a high affinity to CXCR4. SDF-1P2G54 effectively inhibited the chemotactic effect of wild-type SDF-1 to Jurkat cells, and induced rapid CXCR4 internalization in MOLT4 cells.</p><p><b>CONCLUSION</b>SDF-1P2G54 is a new antagonist of CXCR4 with a potential value as an effective inhibitor of HIV-1 infection, cancer metastasis or other major diseases.</p>

Expression, purification and effect of different immunization approaches of Tir from EHEC O157:H7 / 中华微生物学和免疫学杂志

Objective To clone and express translocation intimin receptor(Tir)of enterohemorrhagic Escherichia coli(EHEC)O157:H7,and to analyze the effect of different routes on the induction of immunity to the recombinant protein.Methods The tir eucoding genes were amplified from EHEC O157:H7 strain guangzhou 246 genome,and genes were cloned into the vector pET-30a(+).The pET-30a(+)tir recombinant was transformed into E.coli BL21.and expression was induced bv IPTG.The expressed product was analyzed by SDS-PAGE and purified by Ni-IDA affinity chromatography.The immunized mice sera and fecal against the recombinant protein was detected.Resuits The length of the tir is 1677 bp,with the initiation codon ATG and the termination codon TAA.Double enzyme digestion and DNA sequencing confirmed that the recombinant expression plasmid pET-30a(+)-tir was constructed.The recombinant protein was expressed in Escherichia coli expression system,and was purified by Ni-IDA affinity chromatography.The mice were able to produce a high serum IgG antibody titer after both subeutaneous and intranasal immunizations.Meanwhile,the intranasal immunization induced serum and fecal IgA antibody titer was significantly higher than that of the subcutaneous immunization group.Conclusion Tir molecule is potential vaccine candidate for preventing EHEC disease.

Screening of antigenic epitope of neutrophil-activating protein of Helicobacter pylori by phage display peptide Hbrary / 中华微生物学和免疫学杂志

Objective To identify epitope of neutrophil-activating protein(NAP) of Helicobacter pylori(Hp).Methods Using the mouse monoclonal antibodies against NAP as selective molecular and immunoscrcening phage-display random 7-peptides library.The positive clones were sequenced and analyzed.Phage clones were chosen to immunize mice and to evaluate the potential of phagotopes as effective vaccines.Results One mimotope(FAHLATQ)showed a good match with the NAP at 140-143 AA(AHLA)and the serum of mice induced by the phage clone clearly recognized NAP.Conclusion This study suggests thatthe antigenic epitope could be mapped through screening the phage-display peptide library with monoclonalantibody and a mimotopo of NAP providing an ahernative approach for the diagnosis and development of avaccine for Hp.