Systematic optimization of a domestic nose-only aerosol exposure system for respiratory pathogen research in nonhuman...

Imported aerosol exposure systems for nonhuman primates are often costly and limited in availability, restricting advanced research on respiratory pathogens. To address this, a domestically developed nose-only aerosol exposure system was systematically evaluated and optimized to enhance performance and accessibility. Comprehensive assessment of aerosol generation, transmission, and sampling components revealed key areas for improvement, which were targeted through four modifications: adoption of a vibrating mesh nebulizer for physiologically relevant particle sizes, reduction of plenum chamber volume to minimize losses, shortening of transmission pathways, and addition of 0.25% newborn calf serum to sampling media for viral preservation. These changes collectively minimized viral viability loss during aerosol delivery. The optimizations resulted in a 2.19 log₁₀-units increase in spray factor (SF), enabling aerosol concentrations to exceed 10^4.43 50% cell culture infectious dose (CCID₅₀)/L at the exposure port using 10^7.25 CCID₅₀/mL viral titer in the generator. Functional evaluation with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in cynomolgus macaques (Macaca fascicularis) provided preliminary evidence of feasibility for viral delivery and infection, with detectable viral shedding and seroconversion observed following aerosol exposure. The optimized system represents a domestically developed approach that may complement existing aerosol exposure platforms, addressing challenges related to accessibility and cost. This study provides preliminary evidence supporting the feasibility of this approach for respiratory infectious disease research, with potential applications in vaccine development and pandemic preparedness.