The SARS-CoV-2 receptor-binding domain elicits a potent neutralizing response without antibody-dependent enhancement

The SARS-coronavirus 2 (SARS-CoV-2) spike (S) protein mediates entry of SARS-CoV-2 into cells expressing the angiotensin-converting enzyme 2 (ACE2). The S protein engages ACE2 through its receptor-binding domain (RBD), an independently folded 197-amino acid fragment of the 1273-amino acid S-protein protomer. Antibodies to the RBD domain of SARS-CoV (SARS-CoV-1), a closely related coronavirus which emerged in 2002-2003, have been shown to potently neutralize SARS-CoV-1 S-protein-mediated entry, and the presence of anti-RBD antibodies correlates with neutralization in SARS-CoV-2 convalescent sera. Here we show that immunization with the SARS-CoV-2 RBD elicits a robust neutralizing antibody response in rodents, comparable to 100 {micro}g/ml of ACE2-Ig, a potent SARS-CoV-2 entry inhibitor. Importantly, anti-sera from immunized animals did not mediate antibody-dependent enhancement (ADE) of S-protein-mediated entry under conditions in which Zika virus ADE was readily observed. These data suggest that an RBD-based vaccine for SARS-CoV-2 could be safe and effective.

Recent advance in antiviral drugs for hepatitis C / 中南大学学报(医学版)

Hepatitis C virus (HCV) infection is the leading cause of chronic liver diseases worldwide.There is no vaccine to prevent HCV infection.Current standard of care (SOC) for hepatitis C is pegylated interferon-α (pegIFN-α) in combination with ribavirin (RBV).However,the efficacy of pegIFN-α and RBV combination therapy is less than 50％ for genotype 1 HCV,which is the dominant virus in human.Additionally,IFN and RBV are highly toxic,causing severe side effects.Therefore,it is urgent to develop safer and more efficacious anti-HCV drugs.Over the last decade,a number of HCV-specific inhibitors have been discovered with many of them reached to late stages of clinical trials.Recently,2 HCV NS3 protease inhibitors,telaprevir and boceprevir,have been approved by the Unite States Food and Drug Administration (FDA).This opens up a new era for anti-HCV therapy.Several new classes of antiviral drugs targeting HCV NS3 protease,NS5A and NSSB RNA-dependence RNA polymerase (RdRp) are currently at various stages of preclinical and clinical studies.Upon approval of more NS3 protease,NS5A and NS5B polymerase inhibitors,future clinical studies will lead to optimal combination therapies which will have desirable parameters such as IFN-free,higher efficacy,safe,one daily dose and short duration.