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@#Abstract: Objective To investigate the current status of streptomycin resistance of Yersinia pestis caused by point mutations of rpsL gene in Qinghai, so as to provide theoretical basis for precise clinical medication and prevention of drug resistance of human plague outbreak in South area of Qinghai Province in the future. Methods A total of 104 representative strains of Yersinia pestis collected from plague patients, vector insects and intermediate hosts in South area of Qinghai Province from 1957 to 2009 were screened, isolated and cultured by Hiss agar plates. The DNA of representative Yersinia pestis was extracted by sodium dodecyl sulfate lysis and phenol-chloroform method. The primers forward primer and reverse primer and TaqMan-MGB probes probe1 [FAM] and probe2 [VIC] were designed for the rpsL gene of streptomycin resistance gene in China. Real-time PCR with TaqMan-MGB fluorescent probe was used to detect the mutations of rpsL gene in streptomycin resistance locus of 104 strains of Yersinia pestis in South area of Qinghai Province. Results The FAM test results of 104 strains in South area of Qinghai Province were positive, corresponding to the detection of rpsL (128 : A ), RFU peak >1 000,negative <200. VIC test results of all tested strains were negative, corresponding to the detection of rpsL (128:G), RFU peak <200, positive >1 000. That is, no strains with rpsL gene mutation related to streptomycin resistance were found in the 104 strains of Yersinia pestis in Qingnan Province. Conclusion This study provides basic data on the distribution of streptomycin resistance of Yersinia pestis in South area of Qinghai Province, and lays a foundation for preventing the occurrence of drug resistance and clinical treatment of Yersinia pestis in South area of Qinghai Province.
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@#Abstract: Objective To investigate the clustered regularly interspaced short palindromic repeats (CRISPR) genotypes and regional distribution of Yersinia pestis strains in the natural plague foci of Hainan Tibetan Autonomous Prefecture of Qinghai Province (referred to as "Hainan prefecture") and provide a scientific basis for plague prevention and control in this area. Methods A total of 36 representative Yersinia pestis strains, which were isolated from different host animals and insect vectors from 1954 to 2009 in Hainan Prefecture, were selected as experimental subjects. The DNAs were extracted using the traditional sodium dodecyl sulfate decomposition and phenol-chloroform method. Three pairs of CRISPR primers (YPa, Ypb, YPc) were used for PCR amplification, sequencing and analysis of the DNA of the tested strains, respectively, as a means to identify the CRISPR genotypes of Yersinia pestis in Hainan Prefecture. Results A total of 17 spacers were observed among 36 strains of Yersinia pestis, including 9 of YPa, 5 of YPb and 3 of YPc. All strains were divided into 5 CRISPR gene clusters (Cb2, Cb4 ', Ca7, Ca7 ', Ca35 ') and 6 genotypes (G1, G9, G22, G22-A1 ', G26-A1 ', G26-A1 'A4 -). The G26-a1 ' was the main genotype, which was distributed in Gonghe, Guide and Xinghai County, and the G22 is the second type, which was distributed in Gonghe and Guide County. Conclusions The genetic polymorphism of CRISPR loci of Yersinia pestis strains in Hainan was high, and the regional distribution characteristics of Yersinia pestis strains with different genotypes were significant.
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OBJECTIVE: To investigate reciprocal regulation between Fur and two RyhB homologs in Yersinia pestis( Y. pestis), as well as the roles of RyhBs in biofilm formation. METHODS: Regulatory relationships were assessed by a combination of colony morphology assay, primer extension, electrophoretic mobility shift assay and DNase I footprinting. RESULTS: Fur bound to the promoter-proximal DNA regions of ryhB1 and ryhB2 to repress their transcription, while both RyhB1 and RyhB2 repressed the expression of Fur at the post-transcriptional level. In addition, both RyhB1 and RyhB2 positively regulated Y. pestis biofilm exopolysaccharide (EPS) production and the expression of hmsHFRS and hmsT. CONCLUSION: Fur and the two RyhB homologs exert negative reciprocal regulation, and RyhB homologs have a positive regulatory effect on biofilm formation in Y. pestis.
Subject(s)
Bacterial Proteins/genetics , Biofilms , Gene Expression Regulation, Bacterial/physiology , Yersinia pestis/physiology , Bacterial Proteins/metabolism , Yersinia pestis/geneticsABSTRACT
OBJECTIVE: To evaluate the protective efficacy of plague subunit vaccine, BALB/c mice, guinea pigs and rabbits were used in this study. METHODS: Groups of mice (10 per group), guinea pigs (14 per group) and rabbits (6 per group) were immunized with F1 + rV270 vaccine, EV76 vaccine and alum adjuvant by intramuscular route, respectively. Serum antibody titres of mice, guinea pigs and rabbits were determined by ELISA and the immunized animals were challenged with 10(6) CFU of Y. pestis strain 141 at the 8th week after the primary immunization. RESULTS: The immunized mice, guinea pigs or rabbits with subunit vaccine developed anti-F1 IgG titre of 41 587.3 +/- 2.1, 11 543.7 +/- 2.1 or 522.4 +/- 22.4 and elicited statistical anti-F1 IgG titre difference among them (F = 17.58, P < 0.01). The immunized mice, guinea pigs or rabbits with subunit vaccine had anti-rV270 IgG titre of 15 748.7 +/- 1.6, 12.6 +/- 1.4 or 1648.0 +/- 5.0 and induced statistical anti-rV270 IgG titre difference among them (F value was 16.34, P < 0.01). There was significant anti-F1 IgG titre difference among mice, guinea pigs and rabbits immunized with EV76 vaccine that developed anti-F1 IgG titre of 913.4 +/- 4.5, 937.0 +/- 2.0 or 342.0 +/- 12.0 (F = 23.67, P < 0.01), whereas the immunized mice, guinea pigs and rabbits with EV76 vaccine developed anti-rV270 IgG titre of 12.0 +/- 1.0, 447.0 +/- 10.0, 40.0 +/- 11.0 and there was no anti-rV270 IgG titre difference between them (F = 2.20, P = 0.1314). The immunized mice with subunit vaccine developed significantly higher anti-F1 IgG titres than immunized guinea pigs and rabbits (q value was 30.57 and 19.04, respectively, P < 0.01), and there were no anti-F1 IgG titre differences between the immunized guinea pigs and rabbits (q = 0.04, P = 0.8485). The immunized mice with subunit vaccine developed significantly higher anti-rV270 IgG titres than immunized guinea pigs and rabbits (q value was 27.10 and 19.49, respectively, P < 0.01), and there were no anti-rV270 IgG titre differences between the immunized guinea pigs and rabbits with the subunit vaccine (q = 0.25, P = 0.6187). The immunized mice with EV76 elicited higher anti-F1 IgG titres than immunized guinea pigs and rabbits (q value was 40.67 and 29.10, respectively, P < 0.01), whereas there was no difference of F1 IgG titer between immunized guinea pigs and rabbits (q = 0.06, P = 0.8098). The immunized mice, guinea pigs and rabbits with subunit vaccine provided 100% (10/10), 86% (12/14) and 100% (5/5) protection against 10(6) CFU Y. pestis of challenge, respectively. The immunized mice, guinea pigs and rabbits with EV76 vaccine gave 100% (6/6), 93% (13/14) and 100% (6/6) protection against 10(6) CFU Y. pestis of challenge respectively. CONCLUSION: BALB/c mice is the best small animal model for valuation of protective efficacy of plague subunit vaccine. The guinea pigs showed a high individual variation for this purpose. The rabbits can be used as an alternative model for evaluating plague subunit vaccine.
