Excellence in Research’: Mechanistic Modelling and Validation Approaches to Decontaminate (+) ssRNA Viruses using Ultra-Violet Technologies

The ongoing COVID-19 pandemic has highlighted the need for efficient and cost effective technologies and solutions to mitigate and prevent the spread and transmission of pathogens with pandemic potential in the built environment including residential buildings, schools, and healthcare facilities. Many positive strand RNA (+ssRNA) viruses, which include coronaviruses and noroviruses, are pathogenic to humans and animals.

These viruses can survive in air, aqueous dispersions, and on surfaces. Ultraviolet germicidal systems emitting UV-C radiation (200-280 nm in wavelength) have been proven effective at inactivating viral pathogens attached to various media and substrates including respiratory aerosols, aqueous dispersions, and non-porous surfaces. However, a fundamental understanding of the UV-C sensitivity of ssRNA viruses and their extents, rates, and mechanisms of inactivation by germicidal UV-C radiation has remained elusive.

The overarching goal of this project is to develop and validate a genomic-based model that could be used to 1) estimate the UV-C sensitivity of pathogenic ssRNA viruses and 2) predict the UV-C doses and exposure times required to inactivate such viruses in aqueous dispersions and surfaces. The successful completion of this project will benefit society through the generation of fundamental knowledge and validated modeling tools to guide the design of more efficient UV-C disinfection systems and protocols to mitigate and prevent the spread and transmission of pathogenic ssRNA viruses in the built environment and in communities during future disease outbreaks and epidemics.

Additional benefits to society will be achieved through outreach and educational activities including the mentoring of a post-doctoral research associate, two graduate students, and four undergraduate students at Tennessee State University and one graduate student at the University of Tennessee, Knoxville.

The effectiveness of UV-C irradiation at inactivating viral pathogens in a given medium depends on several factors including viral concentration, radiation dose and exposure time, and the virus UV-C susceptibility (D90) defined as the required radiation dose (Joule/m2) to inactivate 90% of the viral pathogens. However, measured UV-C susceptibility data for many positive strand RNA (+ssRNA) viruses that are pathogenic to humans and animals are not available due to the unique challenges associated with the collection of experimental data on viral pathogens including the need for biosafety level-3 (BSL-3) facilities and a specialized and highly trained workforce.

The goal of this project is to develop and validate a mathematical model (based on viral genomic parameters such as genome size and pyrimidine dinucleotide frequency) that could be used to predict the UV-C susceptibility of pathogenic +ssRNA viruses in air, aqueous dispersions, and onto surfaces at standard ambient conditions. The specific objectives of the research include: 1) Collection and/or generation of UV-C susceptibility data for a set of model ssRNA viruses for model calibration and validation; 2) Development and validation of quantitative structure activity relationships (QSARs) to predict wavelength specific UV-C susceptibility of +ssRNA viruses by analyzing the correlations between genome parameters (genome size, sequence-based pyrimidine dinucleotide frequency value, Trp and Tyr content) and the UV-C susceptibility data that were collected in Objective 1 ; and 3) Development and implementation of a Java computer interface that utilizes the QSARs developed in Objective 2 to estimate the UV-C radiation dose and exposure time required to inactive +ssRNA viruses in air, aqueous dispersions, and onto surfaces.

The successful completion of this project has the potential for transformative impact through the generation of fundamental knowledge, data and modeling tools to guide the design of more efficient, and cost-effective UV-C viral inactivation and disinfection systems and protocols. To implement the education and outreach activities of the project, the Principal Investigators (PIs) plan to integrate the findings from this research into existing undergraduate and graduate courses at Tennessee State University, the University of Tennessee, Knoxville, and Meharry Medical College to provide students with new learning modules with a focus on technologies, solutions, and modeling tools that could guide the mitigation and prevention of the spread and transmission of viral pathogens in the built environment and the food industry.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.