Inhalable vaccine of bacterial culture supernatant extract mediates protection against fatal pulmonary anthrax.

Pulmonary anthrax is the most fatal clinical form of anthrax and currently available injectable vaccines do not provide adequate protection against it. Hence, next-generation vaccines that effectively induce immunity against pulmonary anthrax are urgently needed. In the present study, we prepared an attenuated and low protease activity Bacillus anthracis strain A16R-5.1 by deleting five of its extracellular protease activity-associated genes and its lef gene through the CRISPR-Cas9 genome editing system. This mutant strain was then used to formulate a lethal toxin (LeTx)-free culture supernatant extract (CSE) anthrax vaccine, of which half was protective antigen (PA). We generated liquid, powder, and powder reconstituted formulations that could be delivered by aerosolized intratracheal inoculation. All of them induced strong humoral, cellular, and mucosal immune responses. The vaccines also produced LeTx neutralizing antibodies and conferred full protection against the lethal aerosol challenges of B. anthracis Pasteur II spores in mice. Compared to the recombinant PA vaccine, the CSE anthrax vaccine with equal PA content provided superior immunoprotection against pulmonary anthrax. The preceding results suggest that the CSE anthrax vaccine developed herein is suitable and scalable for use in inhalational immunization against pulmonary anthrax.

H-NS Represses Biofilm Formation and c-di-GMP Synthesis in Vibrio parahaemolyticus.

Objective: This study aimed to investigate the regulation of histone-like nucleoid structuring protein (H-NS) on biofilm formation and cyclic diguanylate (c-di-GMP) synthesis in Vibrio parahaemolyticus RIMD2210633. Methods: Regulatory mechanisms were analyzed by the combined utilization of crystal violet staining, quantification of c-di-GMP, quantitative real-time polymerase chain reaction, LacZ fusion, and electrophoretic-mobility shift assay. Results: The deletion of hns enhanced the biofilm formation and intracellular c-di-GMP levels in V. parahaemolyticus RIMD2210633. H-NS can bind the upstream promoter-proximal DNA regions of scrA, scrG, VP0117, VPA0198, VPA1176, VP0699, and VP2979 to repress their transcription. These genes encode a group of proteins with GGDEF and/or EAL domains associated with c-di-GMP metabolism. Conclusion: One of the mechanisms by which H-NS represses the biofilm formation by V. parahaemolyticus RIMD2210633 may be via repression of the production of intracellular c-di-GMP.

[Concentration and Particle Size Distribution of Microbiological Aerosol During Haze Days in Beijing].

In this study, we evaluated the bacterial, fungal aerosol concentration, and particle size distribution using microbiological aerosol sampler, and analyzed the particles count concentration of PM1.0, PM2.5, PM5.0 and PM10.0 using aerodynamic particle sizer during clear and haze days in Beijing during Jan 8th, 2013 to Feb 4th, 2013. The concentration of bacterial, fungal aerosol, air particulate matter and aerosol distribution were compared between haze days and clear days. Our results indicated that the proportion of fungal particles smaller than 5 micron, which could deposit in lungs or deeper regions, was much higher than bacterial particles. The biological concentration of bacteria and fungi were higher in clear days than in haze days, and there was no statistic difference of the microbiological aerosol distribution. The concentration of air particulate matter were higher in haze days than in clear days, PM10 was the main particulate matters both in clear days and haze days.

[Evaluation of the protective performance of a positive pressure bio-protective clothing against viral aerosol].

OBJECTIVE: To evaluate the protective performance of a positive pressure bio-protective clothing against viral aerosol. METHODS: The suspension of indicating virus phage Phi-X174 was made for viral aerosol generating in a hermetic cabin. The diameter of viral aerosol particles were measured with a aerodynamics size analyzer. By adjusting the inner humidity of the cabin, the protective efficiency of the positive pressure bio-protective clothing against viral aerosol in high and low windshield conditions was determined with Andersen six-stage air sampler sampling and plage forming unit (PFU) counting, respectively. RESULTS: The mass median diameter of Phage Phi-X174 aerosol particles was about 0.922 µm and the background concentration is beyond 2 × 104 particles/m³. The protective efficiency of the clothing against phage Phi-X174 aerosol particles was above 99.9% under different test conditions with the range of viral aerosol concentration between 0 - 23 PFU/m³. Airflow (P = 0.84), environment humidity conditions (P = 0.33) and sampling time (P = 0.07) did not affect the protective efficiency statistically. CONCLUSION: The positive pressure bio-protective clothing provided a relatively high efficiency against phage Phi-X174 aerosol regardless of airflow rate, environment humidity and sampling time.