New BioCascade System for Investigating the Airborne Transmission Modes of Respiratory Viruses - Project Summary
While knowledge of the transmission modes for respiratory pathogenic viruses is critical, understanding
their transmission mechanisms is hampered by existing sampling methods. Commonly used bioaerosol
samplers have low collection efficiencies for particles < 0.3 m (e.g., influenza virus and the recent SARS-
CoV-2), and the process involved in the collection often reduces infectivity, lowering the chances to accurately
assess the extent of the occurrence. To address these issues, we developed under a NIAID grant the VIable
Virus Aerosol Sampler (VIVAS), which has been proven more efficient and reliable in collecting viable viruses
than the industry standard samplers. This system has been tested in the laboratory and the field, and it is now
commercially available as the BioSpot Sampler (sold by our licensee Aerosol Devices Inc.).
Nevertheless, none of the commercial bioaerosol samplers, including the BioSpot, has the capability to
collect size-fractionated airborne particles. Although previous efforts have tried to separate virus-containing
particles by aerodynamic size, maintaining their infectivity during sampling remains challenging. Here, we aim
to develop a novel sampling system, the BioCascade that will allow the collection into liquid of four different
particle fractions: >10 m, PM4-10, PM1-4 and PM1 (fine) while maintaining infectivity. In Phase I, we will build a
BioCascade prototype that can be attached to a VIVAS unit and to a gelatin filter collection device. The
proposed approach will create a powerful tool, not available before, that can transform our current disease-
control paradigm from a reactive approach (to an outbreak after its fact) to a proactive approach (informing us
the forthcoming outbreak.)
Specific aims of this proposal are: 1) Achieve the desired particle size cut-offs (>10 m, PM4-10, PM1-4 and
PM1) while minimizing particle losses in the impactors and efficiently delivering each fraction simultaneously
into a liquid collection medium. Preliminary tests to determine the effective cut-off of the BioCascade will be
conducted at Aerosol Dynamics Inc. in combination with the Viable Virus Aerosol Sampler, using aerosol
particles of known sizes. (2) Demonstrate a high viability/infectivity in the delivered samples while achieving
optimal size separation. The BioCascade unit combined with the VIVAS or the gelatin filter, will be further
tested at the University of Florida using aerosolized microorganisms of different sizes. The effect of the system
on the viability of the samples will be determined. (3) Evaluate the exposure level to influenza viruses at a
Student Health Care Center (SHCC). The BioCascade with the VIVAS will be placed at the waiting room in the
SHCC for collecting respiratory viruses in the four size fractions during the “flu season” to capture the
circulating strains and to determine the pathogen loading in each size fraction.
This information will be of utmost importance to understanding the reach of an outbreak, establishing
recommendations for public safety, and determining the best strategies to control/stop future viral diseases.
