A.N. Sergeev

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.

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

Abstract 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 600m from the source.

Оценка чувствительности животных к особо опасным ортопоксвирусам с использованием первичных культур клеток легких

Objective of the study is to investigate the sensitivity of different animals to highly pathogenic Orthopoxviruses applying techniques, based on utilization of primary cultures of lung cells, and to assess the possibility of further deployment of this approach. Materials and methods. Cultural and virological research methods are used. Results and conclusions. Performed is the assessment of sensitivity of outbred mice, marmots and chickens to variola virus (VV) and monkeypox virus (MPV), using suspended primary cultures of lung cells (SPCLC) of these animals. Through inoculation of the mentioned above cell cultures with VV and MPV in a dose of 0.00001 PFU per a cell (plaque forming unit /cell) demonstrated has been virus replication with maximum concentration values in all cases (1,4 - 2,0 lg PFU/ml), mainly 3 days after infection. According to the data on SPCLC, sensitivity to VV in mice, marmots and chickens (ID 50 - 50 % infective dose) amounts to (1,3 ± 0,5) lg PFU; (2,3 ± 0,5) lg PFU; and (0,0 ± 0,4) lg PFU respectively, taking into account unhindered interaction of the virus with permissive lung cells in the organism of the animals. As for MPV values for this indicator, they are: (1,7 ± 0,3) lg PFU for mice, and (0,5 ± 0,3) lg PFU - for marmots. Obtained ID 50 values for VV using mice SPCLC and for MPV using mice and marmots SPCLC coincide with the ones, studied in direct experiments on intranasal infection with the viruses, with regard to 10 % of the viral application in lungs when deploying the latter method of infection. The fact testifies to the possibility of further deployment of this method for the assessment of animal sensitivity to highly pathogenic Orthopoxviruses based on the results of in vitro experiments.

Analysis of Vaccinal Process Peculiarities in Persons Immunized with Smallpox Live Vaccine in Case of Primary Vaccination and Revaccination

Натуральная оспа – особо опасное, высококонтагиозное заболевание – была ликвидирована в результате программы массового оспопрививания, инициированной ВОЗ в XX веке [3]. В настоящее время существует потенциальная опасность возрождения оспы в случае использования вируса натуральной оспы в качестве агента биотерроризма [1], и ряд стран проводит активную иммунизацию военнослужащих [10, 13]. Кроме того, возможно высвобождение вируса при проведении археологических раскопок в мерзлотных грунтах [5], а также представляют угрозу регулярно появляющиеся вспышки других ортопоксвирусных инфекций среди людей [4, 12]. Ситуация осложняется тем, что после прекращения массовой иммунизации более 30 лет назад в настоящее время около 1/3 всего населения не имеют иммунитета против оспы [3, 13]. Вакцинация остается единственным эффективным способом профилактики натуральной оспы и других ортопоксвирусных инфекций [2, 3]. Некоторые страны разрабатывают и проводят клинические испытания вакцин 3-го поколения, создают БИОТЕХНОЛОГИЯ, ИММУНОЛОГИЯ

Изучение противовирусной активности химически синтезированных соединений в отношении ортопоксвирусов в экспериментах in vitro

for ST-246 and NIOC-14 is within the range of 0,001-0,004 µg/ml, and IS for both of them is > 100000. In addition, ST-246 and NIOC-14 chemical compound efficacy, concentrated up to 0,0125; 0,025 and 0,05 µg/ml, in accordance with prophylactic charts describing an impact on ectromelia virus (EV) infectivity in vitro , is consequently 0,6; 3 and 1 lg higher than in case of compound application after an hour of Vero cells infection with EV.