Crystal structure of SARS-CoV-2 nsp10/nsp162′-O-methylase and its implication on antiviral drug design

Dear Editor,The unexpected outbreak of a novel human coronavirus infection has imposed great threat to public health.Thus far,this newly-identified virus has spread to 215 countries and territories,infected more than 3.5 million people,and caused over 240,000 deaths worldwide.1 Although intensified countermeasures have been implemented globally to control the virus infection,the pandemic is still surging with a daily increase in infection case of over 65,000 ever since April 1st 2020.1 No prophylactic vaccines or clinical drugs are currently available to prevent or treat the disease,namely coronavirus disease 2019(COVID-19).

Research and development of a novel subunit vaccine for the currently circulating pseudorabies virus variant in China

Pseudorabies(PR)is a devastating viral disease which leads to fatal encephalitis and respiratory disorders in pigs.Commercial gE-deleted live pseudorabies virus(PRV)vaccine has been widely used to control this disease in China.However,the new-emerging variants of PRV compromises the protection provided by current vaccines and lead to the outbreak of PR in vaccinated pig herds.Several killed and live vaccine candidates based on current PRV variants have been reported to be effective to control the disease.A subunit vaccine based on gB protein,one major PRV glycoprotein which elicits strong humoral and cellular immune responses,however,was never evaluated for protection against the current circulating PRV variants.In this study,full-length PRV gB protein was successfully expressed in baculovirus/insect cells in the soluble format and was tested on 3-week-old piglets as a subunit vaccine.Compared with unvaccinated pigs,the gB-vaccinated pigs developed specific antibody-mediated responses and were protected from the virulent PRV HN1201 challenge.All vaccinated pigs survived without showing any PRV-specific respiratory and neurological signs,but all unvaccinated pigs died within 7 days after HN1201 challenge.Hence,this novel gB-based vaccine could be applied as an effective subunit vaccine to control PRV variant in China.

S19W,T27W,and N33OY mutations in ACE2 enhance SARS-CoV-2 S-RBD binding toward both wild-type and antibody-resistant viruses and its molecular basis

SARS-CoV-2 recognizes,via its spike receptor-binding domain(S-RBD),human angiotensin-converting enzyme 2(ACE2)to initiate infection.Ecto-domain protein of ACE2 can therefore function as a decoy.Here we show that mutations of S19W,T27W,and N330Y in ACE2 could individually enhance SARS-CoV-2 S-RBD binding.Y330 could be synergistically combined with either W19 or W27,whereas W19 and W27 are mutually unbeneficial.The structures of SARS-CoV-2S-RBD bound to the ACE2 mutants reveal that the enhan ced binding is mainly con tributed by the van der Waals interactio ns mediated by the aromatic side-chai ns from W19,W27,and Y330.While Y330 and W19/W27 are distantly located and devoid of any steric interference,W19 and W27 are shown to orient their side-chains toward each other and to cause steric conflicts,explai ning their in compatibility.Finally,using pseudotyped SARS-CoV-2 viruses,we dem on strate that these residue substitutions are associated with dramatically improved entry-inhibition efficacy toward both wild-type and antibody-resistant viruses.Taken together,our biochemical and structural data have delineated the basis for the elevated S-RBD binding associated with S19W,T27W,and N330Y mutations in ACE2,paving the way for potential application of these mutants in dinical treatment of COVID-19.