SARS-CoV-2 RdRp is a versatile enzyme with proofreading activity and ability to incorporate NHC into RNA by using diphosphate form molnupiravir as a substrate (preprint)

The coronavirus disease 2019 (COVID-19) has been ravaging throughout the world for almost two years and has severely impaired both human health and the economy. The causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) employs the viral RNA-dependent RNA polymerase (RdRp) complex for genome replication and transcription, making RdRp an appealing target for antiviral drug development. Although the structure of the RdRp complex has been determined, the function of RdRp has not been fully characterized. Here we reveal that in addition to RNA dependent RNA polymerase activity, RdRp also shows exoribonuclease activity and consequently proofreading activity. We observed that RdRp and nsp14-ExoN, when combined, exhibit higher proofreading activity compared to RdRp alone. Moreover, RdRp can recognize and utilize nucleoside diphosphate (NDP) as substrate to synthesize RNA and can also incorporate {beta}-d-N4-hydroxycytidine (NHC) into RNA while using diphosphate form molnupiravir as substrate.

If the Coronavirus Doesn't Scare You, the Banners Will-A Case Study of Early COVID-19 Banners.

As a crucial element of China's political and cultural life, "banners," or biaoyǔ, have been around for decades, in support of national-level policies such as family planning and the governing mottos of Presidents. The banners that have emerged during the Covid-19 pandemic which was also the subject of a national-level driven policy, have been involved in a nation-wide public debate over the language styles of banners used to urge people to stay indoors. Based on the analysis of the early COVID-19 banners and the related online comments, this article analyzes the language style patterns of the banners and the mode of banner circulation. The study found that the manner in which the banners are circulated goes beyond a unidirectional path of on-site instant communication. This process is facilitated by social networks and mass media, which, during circulation, twice created a banner upgrade. The upgrades created decontextualization and function extension of the banners, whereas audience feedback triggered an adaptive adjustment of the language style of the banners. This article suggests that the study of the use and spread of banners, especially the early COVID-19 banners, sheds light on the study of mass communication and discourse style, and also how measures to contain pandemics such as COVID-19 can be communicated.