ABSTRACT
Objective To establish TaqMan Real-Time PcR method for detection and identification of Neisseria meningitidis.Methods Seven sets of primers and FAM-labeled probes targeting different genes of Neisseria meningitidis were designed and synthesized.ctrA gene was used for identification of N.meningitidis species.Six serogruops(A,B,C,X,Y,W135)of N.meningitidis were detected with following genes:sacB(A),siaD(B),siaD(C),xcbB(X),synF(Y)and synG(W135)respectively.Sensitivity and specificity of Real-Time PCR were assessed for different primers and probes.121cerebrospinal fluid(CSF)specimens from suspected N.meningitidis invasive meningitis cases were detected by latex agglutination test and Real-Time PCR assay simultaneously.Resuits 79 N.meningitidis isolates of different serogroups could be detected and identified by seven sets of primers and probes in this study.Real-Time PCR seemed more sensitive than standard PCR bv 101-103 times.The respective sensitivities for ctrA,sacB,siaD(B),siaD(C),xcbB,synF and synG were 8,8,80,8,8,80,8 genomeDNA copies in each reaction.Of the 121 CSF specimens,11 were positive for Real-Time PCR and 6 for latex agglutination test.Conclusion Real-Time PCR could rapidly detect and identify N.meningitidis of different serogroups and seemed more sensitive.It could be widely used for diagnose of invasive meningitis caused bv N.meningitidis.
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<p><b>OBJECTIVE</b>To develop fluorescent amplified fragment length polymorphism (AFLP) method and to evaluate the its typing capability with pulsed-field gel electrophoresis (PFGE) in molecular typing of Vibrio cholerae.</p><p><b>METHODS</b>Forty-seven strains of V. cholerae, with different PFGE patterns, were selected as the reference group to optimize the selective primers of AFLP analysis. Eighty-three strains including 20 strains from one epidemic episode, isolated from different provinces during 1961 and 2005, were used to compare the typing abilities of AFLP and PFGE. LI-COR4300 DNA sequencing system was used for AFLP electrophoresis. The images were recorded by Saga(MX) software and transferred to BioNumerics for clustering analysis. A standard protocol for V. cholerae from PulseNet was used in PFGE.</p><p><b>RESULTS</b>When comparison was made with different selective primers on AFLP based on the 47 strains, results showed that the optimized selective primer pair was EcoR I-G/Mse I-T, and the reproducibility of the tests was 99.2%. Eighty-three isolates showed 52 AFLP patterns and 44 PFGE patterns, with D values as 0.9545 (AFLP) and 0.9251 (PFGE) respectively.</p><p><b>CONCLUSION</b>The protocol of fluorescent AFLP on V. cholerae typing was established. AFLP was higher than PFGE in discrimination of V. cholerae which could be used for molecular typing. When combined with PFGE, AFLP became a more insightful tool to identify genome difference of different isolates.</p>
Subject(s)
Amplified Fragment Length Polymorphism Analysis , Methods , Electrophoresis, Gel, Pulsed-Field , Genotype , Phylogeny , Vibrio cholerae , Classification , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To analyze sequences of the housekeeping genes including recA, dnaE, and mdh in different serogroups or different biotypes of Vibrio cholerae (VC) strains isolated from China.</p><p><b>METHODS AND RESULTS</b>recA, dnaE, and mdh genes of Vibrio cholerae were obtained by PCR, sequenced and analyzed. Forty-four variable bases were identified in the 500 bases of recA gene of 18 VC strains, and the mutation of only 3 variable bases could result in changes of 2 amino acids. In the 600 bases of dnaE genes of 18 strains, 32 variable bases were found and only 1 contributed to an amino acid change. In the 367 bases of mdh genes of 18 strains, only 1 variable base was identified whose mutation involved an amino acid convertion. Toxic EI Tor biotype (EVC) strains and toxic O139 serogroup strains were closely related. Non-toxic strains of different serogroups or types were lowly related. Non-toxic and toxic strains of different serogroups or types were lowly related.</p><p><b>CONCLUSION</b>Toxic EVC and toxic O139 serogroup strains isolated from different areas of China may evolve from a common original strain, and toxic O139 VC strains may come from toxic EVC strains.</p>