A. S. Safatov

Inactivation of Viruses in Bubbling Processes Utilized for Personal Bioaerosol Monitoring

ABSTRACT 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 Hanks 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.

Long-Term Sampling of Viable Airborne Viruses

A novel bioaerosol sampling technique, which utilizes the bubbling process in the collection fluid, has recently been developed and found feasible for a long-term personal sampling of airborne bacteria and fungal spores as it maintained high physical collection efficiency and high microbial recovery rate for robust and stress-sensitive microorganisms. Further tests have shown that the new technique also has potential to collect viable airborne viruses, particularly when utilized for a short-term sampling of robust strains. As the short-term sampling has a limited application for assessing personal exposure in bioaerosol-contaminated environments, the present study was undertaken to investigate the feasibility of the “bubbler” for a long-term monitoring of viable airborne viruses. Liquid droplets containing Vaccinia virions (that simulate Variola, a causative agent of smallpox) were aerosolized with a Collison nebulizer into a 400-liter test chamber, from which the droplets were collected by three identical prototype personal samplers in the liquid medium during different time periods ranging from 1 to 6 hours. The viral content was measured in the collection fluid of the sampler and in the initial suspension of the nebulizer using the fluorescence-based method and by enumerating plaque-forming units per milliliter of the fluids. The relative recovery of viruses after the sampling act was determined. The results show that the “bubbling” technique has consistent collection efficiency over time and is capable of maintaining the viability of Vaccinia, for at least 6 hours, with a loss in recovery rate of about 10%. The data demonstrate a good potential of the new technique for measuring personal exposure to robust airborne viruses over a long period.

Monitoring of viable airborne SARS virus in ambient air

Abstract Due to recent SARS related issues (Science 300 (5624) 1394; Nature 423 (2003) 240; Science 300 (5627) 1966), the development of reliable airborne virus monitoring procedures has become galvanized by an exceptional sense of urgency and is presently in a high demand (In: Cox, C.S., Wathers, C.M. (Eds.), Bioaerosols Handbook, Lewis Publishers, Boca Raton, FL, 1995, pp. 247–267). Based on engineering control method (Aerosol Science and Technology 31 (1999) 249; 35 (2001) 852), which was previously applied to the removal of particles from gas carriers, a new personal bioaerosol sampler has been developed. Contaminated air is bubbled through porous medium submerged into liquid and subsequently split into multitude of very small bubbles. The particulates are scavenged by these bubbles, and, thus, effectively removed. The current study explores its feasibility for monitoring of viable airborne SARS virus. It was found that the natural decay of such virus in the collection fluid was around 0.75 and 1.76lg during 2 and 4h of continuous operation, respectively. Theoretical microbial recovery rates of higher than 55 and 19% were calculated for 1 and 2h of operation, respectively. Thus, the new sampling method of direct non-violent collection of viable airborne SARS virus into the appropriate liquid environment was found suitable for monitoring of such stress sensitive virus.

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.

Variability of the content of live microorganisms in the atmospheric aerosol in southern regions of western Siberia.

The results of preliminary studies on the biological component of atmospheric aerosol and annual dynamics of the total atmospheric aerosol protein concentration in the southern regions of Western Siberia were considered in the preceding works [1, 2]. Live microorganisms contained in atmospheric aerosols can be transferred over large distances and to high altitudes without loss of viability [3–7]. Therefore, the properties of the biological component of atmospheric aerosols and sources of their origin should be studied not only near the ground, but also at high altitudes. In this work, we describe the results of measurements of the concentrations of live microorganisms and the compositions of atmospheric aerosols above large forests in the southern regions of Western Siberia.

Measurement Errors in Determining Tropospheric Bioaerosol Concentrations in the Southern Region of Western Siberia

The Research Institute of Aerobiology of the State Research Center of Virology and Biotechnology “Vector” and the Institute of Atmosphere Optics of the Siberian Division, Russian Academy of Sciences have been systematically monitoring tropospheric biogenic aerosols (bioaerosols) in the southern region of Western Siberia since December 1998. Samples of atmospheric air are taken at altitudes of 0.5, 1, 1.5, 2, 3, 4, 5.5, and 7 km using a plane–laboratory Optik-E during one day in the last third of every month to determine the total protein content and the amount of viable microorganisms. The research methods and summarized results of the studies are described in detail elsewhere [1, 2].

Comparison of the presence of chemical and biomarkers in the surface microlayer in water areas of health resort zones of Lake Baikal and in atmospheric aerosol of this region

The search for the chemical and biomarkers of aerosol originating from the surface microlayer (SML) of water areas of health resort zones at Lake Baikal was performed. The concentrations of Ca, Mg, Na, K, Cu, Zn, Fe, Mn, Al, Ba, Pb, Cd, As, naphthalene, acenaphthene, acenaphthilene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, perilene, benz (b) fluoranthene, benz(a) pyrene,1,2,5,6-dibenz anthracene, benz(ghi) perilene, and total protein in aerosols and water samples collected from the region were experimentally studied. A direct close interrelation was revealed between the concentrations of all chemical elements in aerosol and water samples. The highest concentrations were recorded for Ca, Mg, Na, and K. A polymerase chain reaction method was employed to determine the similar interrelation between the genetic materials of microorganisms (bacterioplankton) found in water and aerosol. A completely adequate marker reflecting the presence of aerosol generated by SML of Lake Baikal water was not found.

Periodic Structure of Surface Fields of the Net Atmospheric Protein Aerosol Concentration in the Outskirts of the City of Novosibirsk

The biogenic component of the atmospheric aerosol in the southern regions of Western Siberia is a subject of systematic monitoring implemented at the Vector State Research Center for Virology and Biotechnology in collaboration with some institutes of the Siberian Division of the Russian Academy of Sciences [1–4]. Net atmospheric protein is the most representative component of the biogenic atmospheric aerosol. The first results of studies on the variation of the protein component of tropospheric aerosol above large forests of the southern regions of Western Siberia were reported in [1]. These data were analyzed in more detail in [4]. In parallel with high-altitude monitoring, we also studied the surface fields of the concentration of the biogenic component of the atmospheric aerosol. The goal of this work was to apply the methods of wavelet and harmonic analysis to the processing of the set of experimental data on the mass concentration of the atmospheric aerosol and the concentration of net protein in the surface layer of the atmosphere measured in the outskirts of the city of Novosibirsk.

Complex experiment on the study of microphysical, chemical, and optical properties of aerosol particles and estimation of atmospheric aerosol contribution in the Earth radiation budget

The main aim of the work was complex experimental measurements of microphysical, chemical, and optical parameters of aerosol particles in the surface air layer and free atmosphere. From the measurement data, the entire set of aerosol optical parameters was retrieved, required for radiation calculations. Three measurement runs were carried out in 2013 within the experiment: in spring, when the aerosol generation maximum is observed, in summer (July), when the altitude of the atmospheric boundary layer is the highest, and in the late summer – early autumn, when the second nucleation period is recorded. The following instruments were used in the experiment: diffusion aerosol spectrometers (DAS), GRIMM photoelectric counters, angle-scattering nephelometers, aethalometer, SP-9/6 sun photometer, СЕ 318 Sun-Sky radiometer (AERONET), MS-53 pyrheliometer, MS-802 pyranometer, ASP aureole photometer, SSP scanning photometer, TU-134 Optik flying laboratory, Siberian lidar station, stationary multiwave lidar complex LOZA-M, spectrophotometric complex for measuring total ozone and NO2, multivariable instrument for measuring atmospheric parameters, METEO-2 USM, 2.4 AEHP-2.4m station for satellite data receive. Results of numerical calculations of solar down-fluxes on the Earth’s surface were compared with the values measured in clear air in the summer periods in 2010—2012 in a background region of Siberian boreal zone. It was shown that the relative differences between model and experimental values of direct and total radiation do not exceed 1% and 3%, respectively, with accounting for instrumental errors and measurement error of atmospheric parameters. Thus, independent data on optical, meteorological, and microphysical atmospheric parameters allow mutual intercalibration and supplement and, hence, provide for qualitatively new data, which can explain physical nature of processes that form the vertical structure of the aerosol filed.

Statistics of the concentration of tropospheric bioaerosol.

Although statistical aspects of the distribution of atmospheric impurity concentration have long been a subject of extensive discussion in the literature, this problem is still of considerable theoretical and applied importance. The biogenic component of tropospheric aerosol in the southern regions of Western Siberia is a subject of systematic research at the Research Institute of Aerobiology, Vector State Research Center for Virology and Biotechnology, in collaboration with the Institute of Atmosphere Optics, Siberian Division, Russian Academy of Sciences [1, 2]. The term “biogenic component” is assumed to include only two fractions of atmospheric aerosol: total protein and live microorganisms. The results of the study and preliminary results of their generalization showed that there is a significant scatter of the value of the biogenic component of tropospheric aerosol within the altitude range from 0.5 to 7 km. This effect cannot be attributed to the measuring error alone. Therefore, it should be explained by the statistical nature of the scatter.