Traveling tunable laser projector for UV-blue disinfection dose determinations.

As the COVID-19 pandemic was overtaking the world in the spring of 2020, the National Institute of Standards and Technology (NIST) began collaborating with the National Biodefense Analysis and Countermeasures Center to study the inactivation of SARS-CoV-2 after exposure to different ultraviolet (UV) and blue light wavelengths. This paper describes a 1 kHz pulsed laser and projection system used to study the doses required to inactive SARS-CoV-2 over the wavelength range of 222 to 488 nm. This paper builds on NIST's previous work for water pathogen inactivation using UV laser irradiation.

SARS-CoV-2 inactivation by ultraviolet radiation and visible light is dependent on wavelength and sample matrix.

Numerous studies have demonstrated that SARS-CoV-2 can be inactivated by ultraviolet (UV) radiation. However, there are few data available on the relative efficacy of different wavelengths of UV radiation and visible light, which complicates assessments of UV decontamination interventions. The present study evaluated the effects of monochromatic radiation at 16 wavelengths from 222 nm through 488 nm on SARS-CoV-2 in liquid aliquots and dried droplets of water and simulated saliva.

Comparison of the performance of aerosol sampling devices for measuring infectious SARS-CoV-2 aerosols.

To assess the risk of aerosol transmission of SARS-CoV-2, measurements of the airborne viral concentrations in proximity to infected individuals, the persistence of the virus in aerosols, and the dose of the virus needed to cause infection following inhalation are required. For studies aimed at quantifying these parameters, an aerosol sampling device needs to be employed. A number of recent studies have reported the detection of both genetic material and infectious SARS-CoV-2 virus in air samples collected in clinical settings.

The Stability of an Isolate of the SARS-CoV-2 B.1.1.7 Lineage in Aerosols Is Similar to 3 Earlier Isolates.

Background: Our laboratory previously examined the influence of environmental conditions on the stability of an early isolate of SARS-CoV-2 (hCoV-19/USA/WA-1/2020) in aerosols generated from culture medium or simulated saliva. However, genetic differences have emerged among SARS-CoV-2 lineages, and it is possible that these differences may affect environmental stability and the potential for aerosol transmission.

Methods: The influence of temperature, relative humidity, and simulated sunlight on the decay of 4 SARS-CoV-2 isolates in aerosols, including 1 belonging to the recently emerged B.

The influence of temperature, humidity, and simulated sunlight on the infectivity of SARS-CoV-2 in aerosols.

Recent evidence suggests that respiratory aerosols may play a role in the spread of SARS-CoV-2 during the ongoing COVID-19 pandemic. Our laboratory has previously demonstrated that simulated sunlight inactivated SARS-CoV-2 in aerosols and on surfaces. In the present study, we extend these findings to include the persistence of SARS-CoV-2 in aerosols across a range of temperature, humidity, and simulated sunlight levels using an environmentally controlled rotating drum aerosol chamber.

Increasing Temperature and Relative Humidity Accelerates Inactivation of SARS-CoV-2 on Surfaces.

Coronavirus disease 2019 (COVID-19) was first identified in China in late 2019 and is caused by newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Previous studies had reported the stability of SARS-CoV-2 in cell culture media and deposited onto surfaces under a limited set of environmental conditions. Here, we broadly investigated the effects of relative humidity, temperature, and droplet size on the stability of SARS-CoV-2 in a simulated clinically relevant matrix dried on nonporous surfaces.

Airborne SARS-CoV-2 Is Rapidly Inactivated by Simulated Sunlight.

Aerosols represent a potential transmission route of COVID-19. This study examined effect of simulated sunlight, relative humidity, and suspension matrix on stability of SARS-CoV-2 in aerosols. Simulated sunlight and matrix significantly affected decay rate of the virus.

Simulated Sunlight Rapidly Inactivates SARS-CoV-2 on Surfaces.

Previous studies have demonstrated that SARS-CoV-2 is stable on surfaces for extended periods under indoor conditions. In the present study, simulated sunlight rapidly inactivated SARS-CoV-2 suspended in either simulated saliva or culture media and dried on stainless steel coupons. Ninety percent of infectious virus was inactivated every 6.

Increased expression of glial cell line-derived neurotrophic factor protects against oxidative damage-induced retinal degeneration.

Oxidative damage contributes to retinal cell death in patients with age-related macular degeneration or retinitis pigmentosa. One approach to treatment is to identify and eliminate the sources of oxidative damage. Another approach is to identify treatments that protect cells from multiple sources of oxidative damage.

Superoxide dismutase 1 protects retinal cells from oxidative damage.

Bolstering the endogenous oxidative damage defense system is a good strategy for development of treatments to combat neurodegenerative diseases in which oxidative damage plays a role. A first step in such treatment development is to determine the role of various components of the defense system in cells that degenerate. In this study, we sought to determine the role of superoxide dismutase 1 (SOD1) in two models of oxidative damage-induced retinal degeneration.

Vascular targeting of ocular neovascularization with a vascular endothelial growth factor121/gelonin chimeric protein.

Tumors provide an extremely abnormal microenvironment that stimulates neovascularization from surrounding vessels and causes altered gene expression within vascular cells. Up-regulation of vascular endothelial growth factor (VEGF) receptors has allowed selective destruction of tumor vessels by administration of a chimeric protein consisting of VEGF121 coupled to the toxin gelonin (VEGF/rGel). We sought to determine whether there is sufficient up-regulation of VEGF receptors in endothelial cells participating in ocular neovascularization to permit a similar strategy.