ABSTRACT
The novel coronavirus disease 2019 (COVID-19) infections have rapidly spread throughout the world, and the virus has acquired an ability to spread via aerosols even at long distances. Hand washing, face-masking, and social distancing are the primary preventive measures against infections. With mounting scientific evidence, World Health Organisation (WHO) declared COVID-19 an air-borne disease. This ensued the need to disinfect air to reduce the transmission. Ultraviolet C (UVC) comprising the light radiation of 200-280 nm range is a commonly used method for inactivation of pathogens. The heating, ventilation, and air conditioning (HVAC) systems are not beneficial in closed spaces due to poor or no ability to damage circulating viruses. Therefore, standard infection-prevention practices coupled with a strategy to reduce infectious viral load in air substantially might be helpful in reducing virus transmissibility. In this study, we implemented UV light-based strategies to combat COVID-19 and future pandemics. We tested various disinfection protocols by using UVC-based air purification systems and currently installed such a system in workspaces, rushed out places, hospitals and healthcare facilities for surface, air, and water disinfection. In this study, we designed a prototype device to test the dose of UVC required to inactivate SARS-CoV-2 in aerosols and demonstrate that the radiation rapidly destroys the virus in aerosols. The UVC treatment renders the virus non-infectious due to chemical modification of nucleic acid. We also demonstrate that UVC treatment alters the Spike protein conformation that may further affect the infectivity of the virus. We show by using a mathematical model based on the experimental data that UVC-based air disinfection strategy can substantially reduce the risk of virus transmission. The systematic treatment by UVC of air in the closed spaces via ventilation systems could be helpful in reducing the active viral load in the air.
ABSTRACT
Viruses are dependent on the host tRNA pool, and an optimum codon usage pattern (CUP) is the driving force in its evolution. Systematic analysis of CUP of the coding sequences (CDS) of representative major pangolin lineages A and B of SARS-CoV-2 indicate a single transmission event of a codon-optimized virus from its source into humans. Here, no direct congruence could be detected in CUP of all CDS of SARS-CoV-2 with the non-human natural SARS viruses further reiterating its novelty. Several CDS show similar CUP with bat or pangolin, while others have distinct CUP pointing towards a possible hybrid nature of the virus. At the same time, phylogenetic diversity suggests the role of even silent mutations in its success by adapting to host tRNA pool. However, genomes of SARS-CoV-2 from primary infections are required to investigate the origins amongst the competing natural or lab leak theories.
