Post on 19-Nov-2021
transcript
Presented by : Victor BANDALY
EHESP– Rennes & IMT- Atlantique– Nantes
Dr. Aurélie JOUBERT - Dr. Pierre LE CANN - Pr. Yves ANDRES
INTRODUCTION
3
Air quality is one of the most important topics for public health
Air + bioaerosols
InsideOutside
Micro-organisms- Bacteria-Fungi- Viruses
Respiratory virus :
- High infectivity
- Major public health problem
- Easily transmitted (direct contact, droplets, aerosolization)
-Responsible for absenteeism, loss of working time and high socio-economic cost
INTRODUCTION
4
90% of the time spent is in enclosed spaces (homes, workplaces , gym and transport)
Estimated costs for the French system of care for major respiratory diseases and hospitalizations attributable to air pollution is between 0.9 and 1.8 billion euro/year
(Rafenberg, 2015)
+ -Outdoor Air
Rejeted air
Recovered air
Air conditioned
RecycledAir
Vitiated air Outdoor air
Insufflation of airAir extraction
Ventilator Heatexchanger
Spread and transport of viral particles within buildings
Ventilation System Air Handling Units (AHU)
Filter
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Understand the fate and persistence of respiratory viruses on filters used in
air handling units (AHU)
MATERIALS ET METHODS : VIRUS AND AEROSOLIZATION
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Choice of a model of RNA viruses :- Mengovirus (RNA virus / 30 nm ) similar to Rhinovirus
Cellular support of virus replication: Mengovirus BGM cells (Monkey African Green kidney cell)
Detection of virus multiplication Cytopathic effect (BGM cells)
BGM CELL After 30 min After 30 h
BGM cell Infected by Mengovirus(Cytopathic effect)
MATERIALS ET METHODS : EXPERIMENT SET-UP
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Air pump (generator Omron C29 – CompAir pro) + Suspension of Aerosolized Viruses
(Flow rate 4.5L/min)
Methyl polyethacrylate column
Filter analyzed
No filter
4 cm
BioSampler SKC Flow rate 13 L/min
Fiberglass filter F7 (EN 779-2002)
Laminar Flow Hood
MATERIALS ET METHODS : EXAMPLE OF AN AEROSOLIZATION PROCESS
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Filter F7Camfil TM7 60+
Aerosolization time = 25 min
Laminar Flow Hood
Quantification and detection
Quantification of persistent viruses on filters and those passing
through filters
BioSampler Filter
Detection of infectious viruses(Cell Culture TCID50 )
Quantification of viruses(qPCR)
Quantification of viruses on filters and those passing through filters
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F B
Virus culture
TCID : Tissue culture Infective Dose
MATERIALS ET METHODS : QUANTIFICATION AND DETECTION OF
AEROSOLIZED VIRUSES
MATERIALS ET METHODS : AEROSOLS CHARACTERIZATION
Scanner Mobility Particle Size
(SMPSTM, TSI)
Electrical Low Pressure Impact (ELPITM, DEKATI)
Aerodynamic size
Electric mobility size
10
10 nm – 1 µm
7 nm – 4 µm
Validation by fluorescein (CAS: 518-47-8, Merck KGaA) : Mass balance = 98,72%
Validation by qPCR of Mengovirus : Efficiency = 81%(Initial solution aerosolized of 5,24 1010 GU and 4,24 1010 GU of viral particles recovered)
Evaluation of the effectiveness of the system
Initial sol = 0.795 mg
Rest not aerosolized = 0.064 mg
BioSampler recovered = 0.143 mgFilters recovered = 0.454 mg
Not recovered = 0.13 mg(column + pipes)
(Bailly et al., 2001)The filter F7 shows efficiency between 83,8 and 98,5 %.
Filter 1 Filter 2 Filter 3
Exp.1 efficiency 76,41 98,49 87,81
Exp.2 efficiency 94,73 96,07 91,19
Exp.3 efficiency 92,13 99,70 89,96
Efficiency of filtration = qty collected / qty up-stream
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Evaluation of the filtration efficiency
RESULTS
T°C constante and RH% (min 40 % - max 89%) in the system
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Aerosols characterization of the system
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
10 100 1000 10000
ELPI_BGM_blanc
Mengo
d(N)/d[log(dp)]
d. Aerodynamic (nm)
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
10 100 1000
SMPS_BGM_Blanc
Mengo
d(N)/d[log(dp)]
d. Electric mobility (nm)
d50 ELPI_blanc 52,6 nm
d50 SMPS_blanc 87,15 nm
d50 ELPI_Mengo 80 nm
d50 SMPS_Mengo 76,52 nm
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
7 28.4 56 92.8 154 261 382 612 947 1600 2390 3950
ELPI Mengo (L-1 air)
ElLPI Blanc
qPCR (UG. L-1 air)
(nm)
- Virus can not be aerosolized as single particle
- Aerosolized as groups of viruses (more than 3 viruses) - Associated to proteins or cells debris present in the medium
Mengovirus size = 30 nm
RESULTS
Limit detection
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Viral quantification (qPCR) /
1 log virus lost in the system According to the fluorescein experiment:It is assumed that the loss is on the column and pipes
GU : Genomic unit
Quantity (UG.L-1) Quantity (UG.cm-2)Initial 6,68.107
Fltr.1 3,48.106
Fltr.2 3,02.106
Fltr.3 2,71.106
Bios.1 4,61.105
Bios.2 2,43.105
Bios.3 4,90.105
Bios.4 5,33.106
RESULTS
1E+00
1E+01
1E+02
1E+03
1E+04
1E+05
1E+06
1E+07
1E+08
1E+09
Initialsol.
Fltr.1 Fltr.2 Fltr.3 Bios.1 Bios.2 Bios.3 Bios.4
Quantity (UG.cm-2)
Quantity (UG.L-1 air)
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Evaluation of viral infectivity (TCID)
TCID : Tissue culture Infective Dose
Quantity (TCID.L-1) Quantity (TCID.cm-2)Initial 4,00.108
Fltr.1 3,26.102
Fltr.2 4,23.102
Fltr.3 1,59.102
Bios.1 3,77.101
Bios.2 2,13.101
Bios.3 3,91.101
Bios.4 8,48.102 1E+00
1E+01
1E+02
1E+03
1E+04
1E+05
1E+06
1E+07
1E+08
1E+09
1E+10
Initialsol.
Fltr.1 Fltr.2 Fltr.3 Bios.1 Bios.2 Bios.3 Bios.4
Infectivity (TCID.cm-2)
Infectivity (TCID.L-1 air)
1,0.102 TCID.L-1 of infectious mengovirus pass through the filter (BioSamplers)
1,0. 103 TCID. cm-2 of infectious mengovirus are recovered on the filter
Lost of ≈ 5,6 log of viruses infectivity between initial solution and BioSampler
Remaining viruses are infectious upstream and downstream of the system
Vir
al q
uan
tifi
cati
on
(q
PC
R)
Ev
alu
atio
n o
f vi
ral i
nfe
ctio
sity
(TC
ID)
RESULTS
Comparison : Quantification (qPCR) / Infectiosity (TCID)
On the filter : 106 GU.cm-2 of Mengovirus was detected whose 102 PFU. cm-2 are infectious
In the BioSampler: 105 GU.L-1 of Mengoviruswas detected whose 101 PFU.L-1 are infectious
Loss of 4 log of infectivity1E+00
1E+01
1E+02
1E+03
1E+04
1E+05
1E+06
1E+07
1E+08
Fltr.1 Fltr.2 Fltr.3 Bios.1 Bios.2 Bios.3 Bios.4
Infectivity (PFU.cm-2)
Infectivity (PFU.L-1 air)
Quantity (GU.cm-2)
Quantity (GU.L-1 air)
Persistence of Mengovirus on filters as a function of time
Aerosolization time : 25 min - 24h(25mn-50mn-75mn-6h-10h-24h )
Mengovirus remains infectious on the filter until 10 hours after aerosolization
Continuous air flow in the system
Average Initial 25 50 75 360 600 1440Infectivity (PFU.L-1) 4,43.108 3,43.102 6,27.103 2,11.103 1,63.103 1,82.101 0
1E+00
1E+01
1E+02
1E+03
1E+04
1E+05
1E+06
1E+07
1E+08
1E+09
Initial 25 50 75 360 600 1440
Infectivity (PFU.cm-2)
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Understanding the behavior and persistence of adenovirus on F7 filter in air handling units
The system was validated by fluorescein and is ready to study the aerosolization of viruses
Effect of aerosolization on virus infectivity: loss of 4 log compared to initial solution
A model of DNA respiratory virus, the adenovirus, was tested with the same process
Work in progress :
Viruses pass through filters and remain infectious
Viruses stopped by the filter remain infectious
Effect of time: No infectious virus after 10h of aerosolization on the filter
The virus can not be aerosolized as single particle, it’s associated to other viruses or cell debris or protein
CONCLUSION
The Labrotory team works on bioaerosols
(Bacteria, viruses and fungal)
Pr. Yves ANDRES (co-director): yves.andres@imt-atlantique.fr
Victor BANDALY (PhD student): victor.bandaly@imt-atlantique.fr
Dr. Aurélie JOUBERT : aurelie.joubert@imt-atlantique.fr
Dr. Pierre LE CANN (co-director): pierre.lecann@ehesp.fr