safety-precautions-operating-procedures-an-bsl-4-laboratory-3

Safety Precautions and Operating Procedures in an (A)BSL-4 Laboratory: 3. Aerobiology

Aerosol or inhalational studies of high-consequence pathogens have recently been increasing in number due to the perceived threat of intentional aerosol ...

National Institutes of Health (NIH)

Influenza continues to cause widespread disease and death during winter months. In preclinical studies to evaluate the potential efficacy of drugs and vaccines, influenza challenge virus is usually instilled into the noses of animals in the form of large liquid drops. Since inhalation of aerosolized influenza is commonly associated with human transmission, instillation of challenge virus raises uncertainty about the applicability of results. In order to compare the challenge methods, we established conditions to generate influenza aerosols with a mass median aerodynamic diameter (MMAD) of 1 μm that were delivered to mice in a nose-only inhalation system. In this report, we describe the system and compare the 50% lethal dose (LD(50)) of instilled and inhaled A/PR/8/34 (PR8) in BALB/c mice. The estimated LD(50) for inhaled virus was 8.7 plaque forming units (PFU) and the mean time to death was 7.7 days, whereas the estimated LD(50) for instilled virus was 51.6 PFU and the mean time to death was 8.2 days. Our results show that mice are more sensitive to inhaled virus than virus delivered by intranasal instillation. The murine nose-only inhalation model of influenza infection can be used to infect large numbers of animals simultaneously with well-characterized, homogenous PR8 bioaerosol in a controlled and reproducible manner. This model provides the means to evaluate the efficacy of drug and vaccine candidates against the relevant route of challenge, thereby providing data that may better predict clinical outcome.

Development of a murine nose-only inhalation model of influenza: comparison of disease caused by instilled and inhaled A/PR/8/34.

To evaluate immunity against influenza, mouse challenge studies are typically performed by intranasal instillation of a virus suspension to anesthetized animals. This results in an unnatural environment in the lower respiratory tract during infection, and therefore there is some concern that immune mechanisms identified in this model may not reflect those that protect against infectious virus particles delivered directly to the lower respiratory tract as an aerosol.

Comparison of the effectiveness of antibody and cell-mediated immunity against inhaled and instilled influenza virus challenge.

Aerosol droplets or particles produced from infected respiratory secretions have the potential to infect another host through inhalation. These respiratory particles can be polydisperse and range from 0.05 to 500 µm in diameter. Animal models of infection are generally established to facilitate the potential licensure of candidate prophylactics and/or therapeutics. Consequently, aerosol-based animal infection models are needed to properly study and counter airborne infections. Ideally, experimental aerosol exposure should reliably result in animal disease that faithfully reproduces the modeled human disease. Few studies have been performed to explore the relationship between exposure particle size and induced disease course for infectious aerosol particles. The center flow tangential aerosol generator (CenTAG™) produces large-particle aerosols capable of safely delivering a variety of infectious aerosols to non-human primates (NHPs) within a Class III Biological Safety Cabinet (BSC) for establishment or refinement of NHP infectious disease models. Here, we report the adaptation of this technology to the Animal Biosafety Level 4 (ABSL-4) environment for the future study of high-consequence viral pathogens and the characterization of CenTAG™-created sham (no animal, no virus) aerosols using a variety of viral growth media and media supplements.

Generation and characterization of large-particle aerosols using a center flow tangential aerosol generator with a non-human-primate, head-only aerosol chamber.

The pathogenesis and immune response to Middle East respiratory syndrome (MERS) caused by a recently discovered coronavirus, MERS-CoV, have not been fully characterized because a suitable animal model is currently not available. (18)F-Fluorodeoxyglucose ([(18)F]-FDG)-positron emission tomography/computed tomography (PET/CT) as a longitudinal noninvasive approach can be beneficial in providing biomarkers for host immune response. [(18)F]-FDG uptake is increased in activated immune cells in response to virus entry and can be localized by PET imaging. We used [(18)F]-FDG-PET/CT to investigate the host response developing in nonhuman primates after MERS-CoV exposure and applied kinetic modeling to monitor the influx rate constant (K i ) in responsive lymphoid tissue.

Modeling [(18)F]-FDG lymphoid tissue kinetics to characterize nonhuman primate immune response to Middle East respiratory syndrome-coronavirus aerosol challenge.

Article	Year
Development of a murine nose-only inhalation model of influenza: comparison of disease caused by instilled and inhaled A/PR/8/34. Frontiers in cellular and infection microbiology\| PubMed ID: 22919665	2012
Comparison of the effectiveness of antibody and cell-mediated immunity against inhaled and instilled influenza virus challenge. Virology journal\| PubMed ID: 23777453	2013
Generation and characterization of large-particle aerosols using a center flow tangential aerosol generator with a non-human-primate, head-only aerosol chamber. Inhalation toxicology\| PubMed ID: 25970823	2015
Modeling [(18)F]-FDG lymphoid tissue kinetics to characterize nonhuman primate immune response to Middle East respiratory syndrome-coronavirus aerosol challenge. EJNMMI research\| PubMed ID: 26573211	2015

J. Kyle Bohannon

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