Susceptibility of well-differentiated airway epithelial cell cultures from domestic and wildlife animals to SARS-CoV-2

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread globally, and the number of cases continues to rise all over the world. Besides humans, the zoonotic origin, as well as intermediate and potential spillback host reservoirs of SARS-CoV-2 are unknown. To circumvent ethical and experimental constraints, and more importantly, to reduce and refine animal experimentation, we employed our airway epithelial cell (AEC) culture repository composed of various domesticated and wildlife animal species to assess their susceptibility to SARS-CoV-2. In this study, we inoculated well-differentiated animal AEC cultures of monkey, cat, ferret, dog, rabbit, pig, cattle, goat, llama, camel, and two neotropical bat species with SARS-CoV-2. We observed that SARS-CoV-2 only replicated efficiently in monkey and cat AEC culture models. Whole-genome sequencing of progeny virus revealed no obvious signs of nucleotide transitions required for SARS-CoV-2 to productively infect monkey and cat epithelial airway cells. Our findings, together with the previously reported human-to-animal spillover events warrants close surveillance to understand the potential role of cats, monkeys, and closely related species as spillback reservoirs for SARS-CoV-2.

Identification of five antiviral compounds from the Pandemic Response Box targeting SARS-CoV-2

With currently over 4 million confirmed cases worldwide, including more than 300000 deaths, the current Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic has a major impact on the economy and health care system. Currently, a limited amount of prophylactic or therapeutic intervention options are available against SARS-CoV-2. In this study, we screened 400 compounds from the antimicrobial Pandemic Response Box library for inhibiting properties against SARS-CoV-2. We identified sixteen compounds that potently inhibited SARS-CoV-2 replication, of which five compounds displayed equal or even higher antiviral activity compared to Remdesivir. These results show that five compounds should be further investigated for their mode of action, safety and efficacy against SARS-CoV-2. HighlightsO_LI400 compounds from the pandemic response box were tested for antiviral activity against SARS-CoV-2. C_LIO_LI5 compounds had an equal or higher antiviral efficacy towards SARS-CoV-2, compared to the nucleoside analogue Remdesivir. C_LI

Disparate temperature-dependent virus - host dynamics for SARS-CoV-2 and SARS-CoV in the human respiratory epithelium

Since its emergence in December 2019, SARS-CoV-2 has spread globally and become a major public health burden. Despite its close phylogenetic relationship to SARS-CoV, SARS-CoV-2 exhibits increased human-to-human transmission dynamics, likely due to efficient early replication in the upper respiratory epithelium of infected individuals. Since different temperatures encountered in the human respiratory tract have been shown to affect the replication kinetics of several viruses, as well as host immune response dynamics, we investigated the impact of temperatures during SARS-CoV-2 and SARS-CoV infection in the human airway epithelial cell culture model. SARS-CoV-2, in contrast to SARS-CoV, replicated more efficiently at temperatures encountered in the upper respiratory tract, and displayed higher sensitivity to type I and type III IFNs. Time-resolved transcriptome analysis highlighted a temperature-dependent and virus-specific induction of the IFN-mediated antiviral response. These data reflect clinical features of SARS-CoV-2 and SARS-CoV, as well as their associated transmission efficiencies, and provide crucial insight on pivotal virus - host interaction dynamics.

Efficient inactivation of SARS-CoV-2 by WHO-recommended hand rub formulations and alcohols

The recent emergence of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing COVID-19 is a major burden for health care systems worldwide. It is important to address if the current infection control instructions based on active ingredients are sufficient. We therefore determined the virucidal activity of two alcohol-based hand rub solutions for hand disinfection recommended by the World Health Organization (WHO), as well as commercially available alcohols. Efficient SARS-CoV-2 inactivation was demonstrated for all tested alcohol-based disinfectants. These findings show the successful inactivation of SARS-CoV-2 for the first time and provide confidence in its use for the control of COVID-19. ImportanceThe current COVID-19 outbreak puts a huge burden on the worlds health care systems. Without effective therapeutics or vaccines being available, effective hygiene measure are of utmost importance to prevent viral spreading. It is therefore crucial to evaluate current infection control strategies against SARS-CoV-2. We show the inactivation of the novel coronavirus for the first time and endorse the importance of disinfectant-based hand hygiene to reduce SARS-CoV-2 transmission.

Rapid reconstruction of SARS-CoV-2 using a synthetic genomics platform

Reverse genetics has been an indispensable tool revolutionising our insights into viral pathogenesis and vaccine development. Large RNA virus genomes, such as from Coronaviruses, are cumbersome to clone and to manipulate in E. coli hosts due to size and occasional instability1-3. Therefore, an alternative rapid and robust reverse genetics platform for RNA viruses would benefit the research community. Here we show the full functionality of a yeast-based synthetic genomics platform for the genetic reconstruction of diverse RNA viruses, including members of the Coronaviridae, Flaviviridae and Paramyxoviridae families. Viral subgenomic fragments were generated using viral isolates, cloned viral DNA, clinical samples, or synthetic DNA, and reassembled in one step in Saccharomyces cerevisiae using transformation associated recombination (TAR) cloning to maintain the genome as a yeast artificial chromosome (YAC). T7-RNA polymerase has been used to generate infectious RNA, which was then used to rescue viable virus. Based on this platform we have been able to engineer and resurrect chemically-synthetized clones of the recent epidemic SARS-CoV-24 in only a week after receipt of the synthetic DNA fragments. The technical advance we describe here allows to rapidly responding to emerging viruses as it enables the generation and functional characterization of evolving RNA virus variants - in real-time - during an outbreak.