Structural basis of main proteases of HCoV-229E bound to inhibitor PF-07304814 and PF-07321332

PF-07321332 and PF-07304814, inhibitors against SARS-CoV-2 developed by Pfizer, exhibit broad-spectrum inhibitory activity against the main protease (Mpro) from various coronaviruses. Structures of PF-07321332 or PF-07304814 in complex with Mpros of various coronaviruses reveal their inhibitory mechanisms against different Mpros. However, the structural information on the lower pathogenic coronavirus Mpro with PF-07321332 or PF-07304814 is currently scarce, which hinders our comprehensive understanding of the inhibitory mechanisms of these two inhibitors. Meanwhile, given that some immunocompromised individuals are still affected by low pathogenic coronaviruses, we determined the structures of lower pathogenic coronavirus HCoV-229E Mpro with PF-07321332 and PF-07304814, respectively, and analyzed and defined in detail the structural basis for the inhibition of HCoV-229E Mpro by both inhibitors. Further, we compared the crystal structures of multiple coronavirus Mpro complexes with PF-07321332 or PF-07304814 to illustrate the differences in the interaction of Mpros, and found that the inhibition mechanism of lower pathogenic coronavirus Mpro was more similar to that of moderately pathogenic coronaviruses. Our structural studies provide new insights into drug development for low pathogenic coronavirus Mpro, and provide theoretical basis for further optimization of both inhibitors to contain potential future coronaviruses.

Structural basis of main proteases of HCoV-229E bound to inhibitor PF-07304814 and PF-07321332.

PF-07321332 and PF-07304814, inhibitors against SARS-CoV-2 developed by Pfizer, exhibit broad-spectrum inhibitory activity against the main protease (Mpro) from various coronaviruses. Structures of PF-07321332 or PF-07304814 in complex with Mpros of various coronaviruses reveal their inhibitory mechanisms against different Mpros. However, the structural information on the lower pathogenic coronavirus Mpro with PF-07321332 or PF-07304814 is currently scarce, which hinders our comprehensive understanding of the inhibitory mechanisms of these two inhibitors. Meanwhile, given that some immunocompromised individuals are still affected by low pathogenic coronaviruses, we determined the structures of lower pathogenic coronavirus HCoV-229E Mpro with PF-07321332 and PF-07304814, respectively, and analyzed and defined in detail the structural basis for the inhibition of HCoV-229E Mpro by both inhibitors. Further, we compared the crystal structures of multiple coronavirus Mpro complexes with PF-07321332 or PF-07304814 to illustrate the differences in the interaction of Mpros, and found that the inhibition mechanism of lower pathogenic coronavirus Mpro was more similar to that of moderately pathogenic coronaviruses. Our structural studies provide new insights into drug development for low pathogenic coronavirus Mpro, and provide theoretical basis for further optimization of both inhibitors to contain potential future coronaviruses.

SARS-CoV-2 specific antibody levels after a third dose of inactivated vaccine among 91 medical staff in Chengdu

Objective: To analysis the production of SARS-CoV-2 antibody among medical staff in Public Health Clinical Center of Chengdu 1 month after a third dose of inactivated vaccine (booster shot), and to compare the SARS-CoV-2 antibody among COVID-19 patients after immunization, in order to analyze the effect of the booster shot.

Generation and Effect Testing of a SARS-CoV-2 RBD-Targeted Polyclonal Therapeutic Antibody Based on a 2-D Airway Organoid Screening System.

Coronavirus disease 2019 (COVID-19) is an acute respiratory infectious disease caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The US FDA has approved several therapeutics and vaccines worldwide through the emergency use authorization in response to the rapid spread of COVID-19. Nevertheless, the efficacies of these treatments are being challenged by viral escape mutations. There is an urgent need to develop effective treatments protecting against SARS-CoV-2 infection and to establish a stable effect-screening model to test potential drugs. Polyclonal antibodies (pAbs) have an intrinsic advantage in such developments because they can target rapidly mutating viral strains as a result of the complexity of their binding epitopes. In this study, we generated anti-receptor-binding domain (anti-RBD) pAbs from rabbit serum and tested their safety and efficacy in response to SARS-CoV-2 infection both in vivo and ex vivo. Primary human bronchial epithelial two-dimensional (2-D) organoids were cultured and differentiated to a mature morphology and subsequently employed for SARS-CoV-2 infection and drug screening. The pAbs protected the airway organoids from viral infection and tissue damage. Potential side effects were tested in mouse models for both inhalation and vein injection. The pAbs displayed effective viral neutralization effects without significant side effects. Thus, the use of animal immune serum-derived pAbs might be a potential therapy for protection against SARS-CoV-2 infection, with the strategy developed to produce these pAbs providing new insight into the treatment of respiratory tract infections, especially for infections with viruses undergoing rapid mutation.