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Objective To investigate the Mycobacterium tuberculosis infections in 2014 among Beijing army recruits, and evaluate a new method for screening latent tuberculosis infections.Methods A total of 194 army recruits were subjected to chest X-ray examination purified protein derivative(PPD) skin test, antibody detection, and interferon gamma release assay(IGRA) by ELISA combined with recombinant protein CFP10-ESAT6 and latent infection protein Rv2628.Results The positive rates of PPD skin test and antibody test were 49.7% and 15.5%, respectively.The latent infection rate of IGRA test was 22.2% in 194 cases after CFP10-ESAT6 stimulation.After stimulation of latent tuberculosis infection(LTBI) with Rv2628, IFN-γ level was significantly higher than that in healthy control group (P0.05).There was no significant difference between antibody negative and positive groups after stimulation by CFP10-ESAT6 and Rv2628 (P>0.05).The area under the ROC curve of Rv2628 diagnosis of tuberculosis infection was 0.84.When Youden index was 0.621,the specificity was 94.7% and sensitivity was 67.4%.ConclusionCombined detection of antigens Rv2628 and CFP10-ESAT6 specific IFN-γ values can be potentially used for differential diagnosis of active or latent tuberculosis infections.
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Objective To explore the potential pathogenesis of Yersinia pestis and provide new clues for vaccine development through comparative proteomic analysis of wild-type and pCD1 cured strain of Yersinia pestis 201.Methods Differentially expressed proteins at 26℃ and 37℃ were separated and identified using two-dimensional electrophoresis coupled with mass spectrometry .Results A total of 24 differently expressed proteins were successfully identified from the samples of bacteria grown at 26℃ and 25 proteins at 37℃.Among these, 7 proteins were encoded by pCD 1 plasmid. Conclusion Through comparative proteomic research, we have found that the abundance of several proteins can be dramatically changed when the large plasmid pCD 1 is missing,suggesting that the plasmid can regulate the expression of many genes located in the chromosome .
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Objective To investigate the quinolone resistance determinants in ciprofloxacin-resistant Acinetobacter bau-mannii (ABA)clinical isolates.Methods One hundred and fourteen ciprofloxacin-resistant ABA strains were collected from six Chinese hospitals .The quinolone resistance determining region ( QRDR) of 4 target genes ( gyrA, gyrB, parC and parE) was amplified , sequenced and compared with the reference genome of ATCC 17978 to identify possible resistance-related mutations.Nine plasmid-mediated quinolone resistance (PMQR) genes (qnrA, qnrB, qnrC, qnrD, qnrS, qepA, aac(6′)-Ⅰb-cr, oqxA and oqxB) were also amplified, and the amplicons were then sequenced to determine their character-istics.Results Almost all isolates (113/114, 99.1%) harbored a substitution in codon 83 of gyrA gene, leading to a Ser83Leu mutation.Meanwhile,58.8%(67/114) of the isolates possessed dual mutations of GyrA-Ser83Leu and GyrA-Ser80Leu, which were known determinants for ciprofloxacin resistance .There were also multiple non-synonymous substitu-tions in gyrB, leading to Arg393Ser, Arg393Cys, Thr401Ala, Pro406Ser, Val430Phe, Cys440Ser and Gly480Arg muta-tions with prevalence rates of 95.6%, 0.9%, 96.5%, 96.5%, 100%, 96.5%and 96.5%,respectively.For parE, all the seven mutations were synonymous and found in more than 96%of the tested isolates.For PMQR genes, although 83.3%(95/114) of the isolates were positive for aac(6′)-Ⅰb, nocrmutations were identified.None of the other eight PMDR genes were found in our strain collection .Conclusion Although multiple mutations are identified in gyrB and parE, these mutations might be the characteristic SNP markers for specific clones , unlikely linked to quinolone resistance .No PMQR is found in the tested isolates.Mutations in chromosomal QRDR (GyrA-Ser83Leu and ParC-Ser80Leu) are the main determi-nants of ciprofloxacin resistance in our ABA collection .
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In the present study, the expression, purification, toxicity detection and the adjuvant effect of the heat-labile enterotoxin in non-toxic mutant mLT63 of Escherichia coli were investigated, in which the inductive expression was performed under optimal condition for inductive expression and the toxicity of the products obtained from inductive expression were tested for toxicity after being purified and concentrated with affinity chromatography. BALB/c mice were immunized orally with the mutant mLT63 associated with Helicobacter pylori (Hp) subunit vaccine UreB, Omp11. After immunization, the specific antibody levels in serum, extract from gastric tissues and fecal extract were determind by means of ELISA assay and the results were subjected to statistical analysis. It was demonstrated that the mutant mLT63 of heat-labile entrotoxin of E.coli constructed in our laboratory devoided of any toxic effect as revealed by the rabbit ileal loop assay, but its adjuvant effect could be demonstrated in the associated immunization of mice with Hp subunit vaccine UreB and Omp11.