Overview
Ultraviolet radiation has a proven germicidal power, and lamps that emit at 254 nm are currently used to sterilise surfaces and environments. Although many experiments have been carried out to assess the susceptibility of some viruses and bacteria to UV, it is not feasible to carry out laboratory tests for every pathogen. For this reason, a computational model based on genomic content could be very useful in order to quickly evaluate how much ultraviolet radiation is needed to inactivate a pathogen. The most promising field of application is that of sanitising hospital environments to eliminate drug resistant pathogens and, following the COVID-19 pandemic, sanitise public offices.
Objectives & Challenges
The aim of the U-Vir project is to develop a computational model (U-VIR) capable of assessing the susceptibility of SARS-Cov-2 and other viruses to the ultraviolet spectrum (UVC) and to validate the model through laboratory tests with a UVC irradiating system.
The lethal effect of UV radiation is primarily due to the structural defects caused when thymine dimers form, but secondary damage is also produced by cytosine dimers. The exact sequences of thymine, cytosines, adenines, and guanines in DNA/RNA is correlated to UV susceptibility.
The computational model allows the evaluation of the correct UV dose needed to inactivate viruses (double stranded and single stranded RNA/DNA) and bacteria based solely on their genomic content without the need to perform expensive laboratory experiments for an accurate measure.
Main Findings
The U-Vir computational model has been validated both by using experimental data retrieved from about seventy scientific articles and by performing a laboratory measurement of the Sars-Cov-2 susceptibility to UV.
The computational model has been included in a desktop application that allows the user to evaluate the correct UV dose (@254 nm) needed to have a log-1 reduction (D90) of a certain virus or bacteria. After opening the application, the user can access the “UV Susceptibility Calculator” tab, where they can set up the following parameters:
- Organism Name: the scientific organism name (e.g. Hepatovirus A) or the Accession Assembly (e.g. GCF_000860505.1). The system automatically will search the organism in the NCBI (National Center for Biotechnology Information) database. If the organism does not exist an alert is provided.
- Radius: the logmean of the envelope of the organism measured in μm. If this data is not available, the user can check some values in the tab “Organism – UV Susceptibility Data”.
- Organism Type: the type of model used for the evaluation of UV susceptibility.
- Temperature: the environment's temperature. Default value is 25°C
- Relative Humidity: the environment's relative humidity from 0 to 100%. Default value is 50%.
After processing the information, the correct ultraviolet dose needed to obtain 90% reduction of the virus is given.
Main Recommendations
The U-Vir Project has achieved important results in support of Open Science at a European level as it provides an analysis tool that does not yet exist and is available with an “open access” policy. Thanks to the project, it is now possible to evaluate the correct ultraviolet dose needed to inactivate any virus or bacterium whose genomic chain is known, without having to perform laboratory analysis. Further developments are planned in the following areas:
- Technology improvement
- Cloud deployment of the processing chain to reduce computation times, especially in the case of bacteria and fungi.
- Development of additional functionalities in the web-application
- Communication & Dissemination
- Advertise the project in order to involve scientific communities (research institutes or public bodies in the health sector) in the use of the model.
- Involvement of scientific partners for the use of the system and for further experimental activities aimed at improving the model.
- Modelling enhancement
- Optimisation of the model for bacteria
- Development of models for more complex organisms such as fungi
- Improve the model considering other wavelengths that are effective in deactivating viruses such as the radiation emitted at 222 nm by excimer lamps, and consequently perform validation activity in the laboratory.
- New Application domain
- Apply the model to viruses and plant bacteria for applications in the agricultural sector. Ultraviolet radiation could be used to reduce the presence of pathogens on plants thereby reducing the risk of disease. This would make it possible to reduce the use of chemicals therefore increasing environmental sustainability.
