Miniature PCR based portable bioaerosol monitor development.

AIMS: A portable bioaerosol monitor is greatly demanded technology in many areas including air quality control, occupational exposure assessment and health risk evaluation, environmental studies and, especially, in defence and bio-terrorism applications. Our recent groundwork allowed us to formulate the concept of a portable bioaerosol monitor, which needs to be light, user friendly, reliable and capable of detecting airborne pathogens within 1-1·5 h on the spot. METHODS AND RESULTS: Conceptually, the event of a bioaerosol concentration burst is determined by triggers to commence the representative air sampling with sequential real-time polymerase chain reaction (PCR) confirmation of the targeted micro-organism present in the air. To minimize reagent consumption and idle running of the technology, an event of a bioaerosol burst is confirmed by three parameters: aerosol particle size, concentration and composition. Only particle sizes above 200 nm attract interest in the bioaerosol. Only an elevated aerosol concentration above the threshold (background aerosol concentration) is a signal to commence the analytical procedure. The combination of our previously developed personal bioaerosol sampler, aerosol particle counter based trigger and portable real-time PCR device formed the basis of the bioaerosol monitoring technology. The portable real-time PCR device was advanced to provide internally controlled detection, significantly reducing false-positive alarms. CONCLUSIONS: The technique is capable of detecting selected airborne micro-organisms on the spot within 30-80 min, depending on the genome organization of the particular strain. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to recent outbreaks of infectious airborne diseases and the continuing threat of intentionally released bioaerosol attacks, investigations into the possibility of the early and reliable detection of pathogenic micro-organisms in the air is becoming increasingly important. The proposed technology consisting of a bioaerosol sampler, technology trigger and PCR device is capable of detecting selected airborne micro-organisms on the spot within a short time period.

Surface plasmon resonance-based bacterial aerosol detection.

AIMS: In the area of bioaerosol research, rapid methods for precise detection attracted much interest over last decades. One of such technologies operating in nearly real-time mode without any specific labelling is known as surface plasmon resonance (SPR). Recently, we validated a SPR protocol in conjunction with our earlier developed personal bioaerosol sampler for rapid detection of airborne viruses. Considering that the biological interaction between targeted micro-organism and corresponding antibody is strongly related to sizes of targeted micro-organisms, this research is vital validating suitability of SPR technique for bacterial aerosol detection, as characteristic size of bacteria is 2-3 orders of magnitude larger than sizes of common viruses. The combination of SPR with portable air sampling instrumentation could lead to the development of portable bioaerosol monitor. METHODS AND RESULTS: This study is focussed on the SPR technology application for direct detection of common environmental bacterial strain-Escherichia coli. The detection limit of developed SPR techniques based on utilization of a planar gold sensor chip functionalized with polyclonal antibody via NeutrAvidin junction for sensing of bacterial cells was found to be 1·5 × 10(3)  CFU ml(-1) , which corresponds to the limit of detection in the air to be 2·19 × 10(4)  CFU l(-1) for 1 min of sampling time. CONCLUSIONS: The technology was found fully suitable for rapid and reliable detection of large size bacterial aerosols. Low magnitude of the limit of detection looks very promising for sensitive detection of highly pathogenic airborne bacteria in the ambient air. SIGNIFICANCE AND IMPACT OF THE STUDY: The suggested technology based on a simple model organism is one of the first attempts to develop a real-time monitor for reliable detection of airborne bacteria. The outcomes would be of strong interest of professionals involved in monitoring and/or control of pathogenic airborne bacteria, including Legionella, Mycobacterium tuberculosis and Bacillus anthracis.

Surface plasmon resonance-based real-time bioaerosol detection.

AIMS: Rapid and precise bioaerosol detection in different environments has become an important research and technological issue over last decades. Previously, we employed a real-time PCR protocol in conjunction with personal bioaerosol sampler for rapid detection of airborne viruses. The approach has been proved to be specific and sensitive. However, a period of time required for entire procedure was in manner of hours. Some new developments are required to decrease the detection time down to real-time protocols. METHODS AND RESULTS: Presently, a surface plasmon resonance (SPR)-based immunosensor that coupled with a specific antigen-antibody reaction could offer sensitive, specific, rapid and label-free detection. This study describes the possibility of combining the personal sampler with SPR technology for qualitative and extremely rapid detection of airborne micro-organisms. Common viral surrogate MS2 bacteriophage, frequently used in bioaerosol studies, was employed as a model organism. The results of the sensor functionalizing procedure with monoclonal anti-MS2 antibody and optimization of the chip performance are presented. The SPR-based detection of the airborne virus was found to be very fast; the viral presence was detected in less than 2 min, and the entire procedure (sampling and analysis) was undertaken in 6 min, which could be considered as real-time detection for this type of measurements. CONCLUSIONS: The combination of SPR with the personal sampler targeted towards bioaerosol detection was proven to be feasible. The SPR sensor was found to be highly stable and suitable for multiple utilizations without significant decrease in response. The suggested approach opens new possibilities for the development of portable and rapid (almost real time) bioaerosol monitors. SIGNIFICANCE AND IMPACT OF THE STUDY: This technology is the first in the world real-time bioaerosol monitor. This outcome would be of strong interest to individuals representing public health, biosecurity, defence forces, environmental sciences and many others.

Infection of chickens caused by avian influenza virus A/H5N1 delivered by aerosol and other routes.

This study presents results of the study of infectivity of avian influenza virus (AIV) A subtype H5N1 strains isolated from agricultural birds across the territory of the Russian Federation and CIS countries. The results of the susceptibility of chickens to the AIV isolates delivered by the aerosol route and the dissemination of the virus in the organs of infected birds are presented. As was observed, the sensitivity of birds to AIV by the aerosol route of infection is 30 times higher than by intranasal route, 500 times higher than by the oral route and 10000 times higher than by the intragastric route of infection, which is indicative of higher permissivity of respiratory organs to AIV. The highest titres of AIV A subtype H5N1(A/Chicken/Kurgan/05/2005 strain) in aerosol-infected chickens were found in nasal cavity mucosa, lungs, cloaca, serum and kidney, where viable virus accumulation was detected by 18h post-infection (p.i.). The highest virus titres were observed 54h p.i. in lungs, serum and kidney, reaching the value of 8.16 lg EID50 /g(ml) in the lungs. The results showed that birds infected by the aerosol route developed higher titres of virus than those infected by other routes.

Personal sampler for monitoring of viable viruses; modelling of outdoor sampling conditions.

A new personal bioaerosol sampler has recently been developed and verified to be very efficient for monitoring of viable airborne bacteria, fungi and viruses. The device is capable of providing high recovery rates even for microorganisms which are rather sensitive to physical and biological stresses. However, some mathematical procedure is required for realistic calculation of an actual concentration of viable bioaerosols in the air taking into account a rate of inactivation of targeted microorganisms, sampling parameters, and results of microbial analysis of collecting liquid from the sampler. In this paper, we develop such procedure along with the model of aerosol propagation for outdoor conditions. Combining these procedures allows one to determine the optimal sampling locations for the best possible coverage of the area to be monitored. A hypothetical episode concerned with terrorists' attack during music concert in the central square of Novosibirsk, Russia was considered to evaluate possible coverage of the area by sampling equipment to detect bioaerosols at various locations within the square. It was found that, for chosen bioaerosol generation parameters and weather conditions, the new personal sampler would be capable to reliably detect pathogens at all locations occupied by crowd, even at distances of up to 600 m from the source.

Performance of activated carbon loaded fibrous filters on simultaneous removal of particulate and gaseous pollutants.

Activated carbons are used for the removal of volatile organic compounds (VOCs) from contaminated air carriers. Various arrangements, including fixed and fluidised layers, are employed to meet air quality standards for industrial and domestic applications. Filters are commonly used for the removal of small particles from gas streams. The selective performance of these devices can be high for the removal of either particles or VOCs. However, none of them can be used solely for the simultaneous removal of both contaminants, as their performance for the removal of the alternate group of pollutants is usually very poor. The scope of this project is to combine the above control technologies by loading fibrous filters with activated carbon powder and to investigate the performance of such a single-stage technology on the simultaneous removal of VOCs and particles from the gas stream under controlled laboratory conditions. It was found that the efficiency of the carbon loaded filter was about twice as high as the efficiency of the clean filter with respect to the removal of particles (monodisperse polystyrene latex spheres were used for the measurements) with a corresponding increase of the pressure drop across the filter by around 25-35%. Also, carbon loaded filters were capable of purifying VOC (toluene) concentrated air streams over quite substantial time periods.

Inactivation of viruses in bubbling processes utilized for personal bioaerosol monitoring.

A new personal bioaerosol sampler has recently been developed and evaluated for sampling of viable airborne bacteria and fungi under controlled laboratory conditions and in the field. The operational principle of the device is based on the passage of air through porous medium immersed in liquid. This process leads to the formation of bubbles within the filter as the carrier gas passes through and thus provides effective mechanisms for aerosol removal. As demonstrated in previous studies, the culturability of sampled bacterium and fungi remained high for the entire 8-h sampling period. The present study is the first step of the evaluation of the new sampler for monitoring of viable airborne viruses. It focuses on the investigation of the inactivation rate of viruses in the bubbling process during 4 h of continuous operation. Four microbes were used in this study, influenza, measles, mumps, and vaccinia viruses. It was found that the use of distilled water as the collection fluid was associated with a relatively high decay rate. A significant improvement was achieved by utilizing virus maintenance fluid prepared by using Hank's solution with appropriate additives. The survival rates of the influenza, measles, and mumps viruses were increased by 1.4 log, 0.83 log, and 0.82 log, respectively, after the first hour of operation compared to bubbling through the sterile water. The same trend was observed throughout the entire 4-h experiment. There was no significant difference observed only for the robust vaccinia virus.