30 and 32 kDa outer membrane proteins of Bordetella pertussis as a modulator on promoting degranulation of mast cells

The correlation between the activities of the outer menbrane proteins （OMPs） of Bordetella pertussis and the lgE-mediated asthma was investigated in the present study, in which the OMPs of B. pertussis and their components were prepared by detergent treatment and chromatography, and the molecular weights of the OMPs components were determined by SDS-PAGE. The amounts of total as well as the ovalbumin （OVA）-specific IgE induced by dead B. pertussis whole bacterial vaccine on guinea pigs were detected by ELISA. Meanwhile, the effect of the OMPs and their components to promote the degranulation of guinea pig mast cells was observed by using the mast cell degranulation test, and ELISA assay was used to measure the histatmine levels in the supematants from the mast cell cultures. Histamine sensitive test was used to demonstrate the effects of the OMPs and their components to increase the histamine lethal sensitivity in mice. It was found that four components with molecular weights of 30, 32, 38 and 69 kDa could be obtained from the OMPs of B. pertussts, and the dead whole bacteria vaccine of B. pertussis had the ability to increase the levels of the total as well as the OVA-specific IgE in sera of guinea pigs. The OMPs and their 30 and 32 kDa components demonstrated significantly enhancing effect on the degranulation of guinea pig mast cells, and the histamine levels in the supematants from the mast cell culture treated with OMPs and their 30 and 32 kDa components were also significantly increased. It is evident that the strong adjuvant activity and the enhancing effect to degranulation of mast cells and the release of histamine of certain outer membrane components of B. pertussis could be demonstrated as revealed by the results of the present study, suggesting the possibility of a close relationship between the infection of vaccination with B. pertussis and the IgE-mediated asthma.

Biosynthesis and transfer of 2‑acetamido‑4‑methylamino‑l‑fucose to the core‑lipid A in Bordetella pertussis

The trisaccharide unit in lipopolysaccharide of Bordetella pertussis is important for immune recognition,but how the rare sugar 2-acetamido-4-methylamino-fucose in the trisaccharide unit is synthesized and transferred to the core of lipopolysaccharide in B.pertussis remains unclear.In this study,we demonstrated that the genes bplF,bplG,bplL and bplI are involved in the synthesis and transfer of 2-acetamido-4-methylamino-fucose to the core of lipopolysaccharide in B.pertussis.These genes were overexpressed with various combination in a recombinant E.coli strain which can synthesize B.pertussis corelipid A.Lipopolysaccharides were isolated from these strains and analyzed by using SDS-PAGE,ion chromatography and NMR.Based on these analyses,the mechanism of biosynthesis and transfer of 2-acetamido-4-methylamino-l-fucose to the core-lipid A in B.pertussis is proposed.

Clinical characteristics,molecular epidemiology and antimicrobial susceptibility of pertussis among children in southern China

Background Increasing numbers of pertussis cases have been reported in recent years.The reported cases from Shenzhen Children's Hospital were close to one tenth of all cases in China.The epidemiology of antigenic genotype and antibiotic resistance of circulating strains in children have been unknown in Shenzhen,southern China.The aim of this study was to describe the clinical features and explore the genotypes and antimicrobial susceptibility of circulating Bordetella pertussis among children in Shenzhen.Methods Data of hospitalized children with pertussis in Shenzhen Children's Hospital from August 2015 to April 2017 were collected.The genetic variability of isolates was investigated and Etest was performed for phenotypic susceptibility to erythromycin,azithromycin,clarithromycin,clindamycin,and trimethoprim/sulfamethoxazole.Results 469 children with pertussis confirmed by real-time quantitative polymerase chain reaction were hospitalized and strains were isolated from 105 patients.White blood cell count≥20×10^9/L and lymphocyte proportion≥60%were observed in 39.29%of infants younger than 3 months.The two predominant profiles of virulence-associated allelic genes were ptxA1/ptxC1/ptxPl/prnl(48.6%)and ptxA1/ptxC2/ptxP3/prn2(44.8%).Among the isolates,48.6%(51/105)were found resistant to macrolides.Conclusions These findings indicate that leukocytosis is not a sensitive indicator of pertussis.Isolates with the gene profile ptxP3/prn2 were highly circulating in Shenzhen and less resistant to macrolides,different from patterns observed in other parts of China.

Protective Effect of Anisodsmine on Brain Edema Induced by Pertussis Bacilli in Rabbits

Objective: To observe the effect of 654-2 on brain edema model induced by pertussis bacilli in rabbits. Methods: Brain edema model of 26 rabbits induced by pertussis bacilli was prepared for observation,their brain water content and brain glutamate level were determined before and after treatment. Results: 654-2could decline the water content of brain and increase the glutamate level in brain tissue of the treatment group as compared with group without treatment. Conclusion: 654-2 has protective effect on brain edema induced by pertussis bacilli.