Expression and immunogenicity of recombinant Mycobacterium bovis Bacillus Calmette-Guérin strains secreting the antigen ESAT-6 from Mycobacterium tuberculosis in mice / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Tuberculosis remains the leading cause of human death. Currently, Bacillus Calmette-Guérin (BCG) is the only available vaccine against tuberculosis but its efficacy is highly variable. Thus, developing new tuberculosis vaccines becomes an urgent task. In this study, we evaluated in BALB/c mice the humoral and cellular immune responses of recombinant BCG expressing the antigen ESAT-6 from Mycobacterium tuberculosis.</p><p><b>METHODS</b>Escherichia coli-BCG shuttle plasmid named pDE22-esat-6 was constructed by inserting the BamHI/EcoRI digested esat-6 gene PCR product into the similarly digested parental plasmid pDE22. BCG cells were transformed with pDE22-esat-6, which was named recombinant BCG (rBCG). BALB/c mice were immunized subcutaneously on the back with 100 microl normal saline containing 10(6) CFU of BCG or rBCG. They were sacrificed after 4 weeks to detect their humoral and cellular responses.</p><p><b>RESULTS</b>There was no any significant differences in the growth characteristics between the conventional BCG and rBCG. In immunized mice, the IgG antibody titres of rBCG group were as high as 1:8000, which was significantly higher than that in BCG group (1:1400, P < 0.05). The elicited IFN-gamma level of rBCG group was (1993 +/- 106) pg/ml, which was also significantly higher than that in BCG group ((1463 +/- 105) pg/ml, P < 0.05). The splenocyte proliferation index of rBCG group reached 4.34 +/- 0.31, which was higher than that of BCG group (3.79 +/- 0.24, P < 0.05).</p><p><b>CONCLUSION</b>rBCG secreted expressing antigen ESAT-6 stimulated stronger humoral and cellular immune responses than BCG did, and, therefore may be the better vaccine against mycobacterium tuberculosis.</p>

Relationship between human herpesvirus 6 infection and oral squamous cell carcinoma / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To study the relationship between human herpesvirus 6 (HHV-6) and oral squamous cell carcinoma.</p><p><b>METHODS</b>The serum anti-HHV-6 antibody titers from oral squamous cell carcinoma patients and control subjects were detected by indirect immunofluorescence assay. HHV-6 DNA in peripheral blood mononuclear cells from oral squamous cell carcinoma patients and control subjects was amplified by PCR with primers from sequence of HHV-6 and the specificity was confirmed by Southern-blot hybridization with an internal probe oligonucleotide. An immunohistochemical staining using rabbit anti-HHV-6 antibody was used to detect HHV-6 antigen in oral tumor tissues from oral squamous cell carcinoma patients.</p><p><b>RESULTS</b>Significantly higher proportion of patients with oral carcinoma (16/16) had IgG antibody to HHV-6 in sera compared with those (12/16) in control subjects, and geometric mean titer of these two groups was 1:118 and 1:64 respectively (P less than 0.05). The detectable rate of HHV-6 DNA in peripheral blood mononuclear cells for the above groups was 10/16 and 6/16 respectively (P less than 0.05). HHV-6 antigens were positive in 9 out of 12 oral tumor cases and in only 2 out of 8 pericancerous tissues the difference between these two groups was also significant (P less than 0.05).</p><p><b>CONCLUSION</b>These results demonstrated the frequent presence of HHV-6 in oral squamous cell carcinoma, therefore, HHV-6 possibly play a role in the pathogenesis of oral squamous cell carcinoma.</p>

Analysis on genotypes and their epidemiology of MLS_B resistant Staphylococcus epidermidis isoloates causing nosocomial infections / 中华检验医学杂志

Objective To determine the genotypes and their epidermiology of microlide, lincosamide and streptogramin B(MLS_B)resistant S.epidermidis isolates causing nosocomial infection.Method 126 isolates were collected from inpatients in three hospitals in Beijing from 2003-2004 for testing the antibiotic susceptibility to the macrolide erythromycin,the lincosamide clindamycin.The resistance phenotypes of erythromycin-resistant isolates were determined by the double-disc test with erythromycin and clindamycin.The presence of the relative genes(ermA,ermB,ermC and msrA)to MLS_B resistance was identified by PCR and the similarity of the isolates was analyzed by PFGE.Result The isolates were mostly resistant to macrolide and lincosamide.In the constitutive phenotype cMLS_B isolates,the methicillin resistant S.epidermidis(MRSE)proportion appeared high(78.5%),whereas high methicillin susceptible S.epidermidis(MSSE)proportion was found in the inducible MLS_B phenotype(iMLS_B) (69.2%).ermC was shown as the most frequent determinant to the resistance,not only in MRSE and MSSE (70.8% and 6.8%),but also in iMLS_B and cMLS_B(76.9% and 90.3%).No specific endemic strain was found by PFGE analysis.The same resistance phenotype pattern was not clustered together and distributed into type A～F at the similarity of 60%.Among the phenotypes(cMLS_B,iMLS_B and MS phenotype),no significant difference was shown in the PFGE genotype distribution.Conclusion Our results indicate that the MLS_B resistance in S.epidermidis causing nosocomial infection is prevalent in the hospital and MLS_B antibiotics should be used iudiciously,ermC was shown as the most frequent determinant to the resistance.

Biofilm Production in Staphylococcus epidermidis Isolated from Hosocomial Infection / 微生物学通报

To determine the relationship between the intercellular adhesion operon (ica) and the biofilm production in Staphylococcus epidennidis isolates from nosocomial infection, and the affection of ica on the antibiotic susceptibility of the isolates, we collected 106 strains, epidermidis isolates from nosocomial infection specimen to detect their biofilm production by quantitative and qualitative method and investigate the existence of ica operon by PCR. The minimal inhibitory concentration (MIC) to erythromycin, ampicillin, cefoxitin, ceftriaxone, teco-planin, ciprofloxacin, tetracycline, trimethoprim-sulfamethoxazole and vancomycin were tested. Among the isolates, 33 (31. 1% ) of them were detected out carrying ica operon. The rate of biofilm production of the ica-posi-tive isolates was higher than that of the ica-negative (P =0. 001) . By adding glucose and NaCl into the culture the detection rate of biofilm production could be increased. The antibiotic susceptibility of the plankton cells of ica-positive isolates to erythromycin, cefoxitin and ceftriaxone , except ampicillin, ciprofloxacin, tetracycline and tremethoprim-sulfamethoxazole, were lower than those of ica-negative isolates. This study showed that the existence of ica operon was close related to the biofilm formation in 5. epidermidis isolates from nosocomial infection. However, the mechanism of antibiotic resistance of the strains inside the biofilm still needed to be illustrated.