The E484K Substitution in a SARS-CoV-2 Spike Protein Subunit Vaccine Resulted in Limited Cross-Reactive Neutralizing Antibody Responses in Mice.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), especially emerging variants, poses an increased threat to global public health. The significant reduction in neutralization activity against the variants such as B.1.351 in the serum of convalescent patients and vaccinated people calls for the design of new potent vaccines targeting the emerging variant. However, since most vaccines approved and in clinical trials are based on the sequence of the original SARS-CoV-2 strain, the immunogenicity and protective efficacy of vaccines based on the B.1.351 variant remain largely unknown. In this study, we evaluated the immunogenicity, induced neutralization activity, and protective efficacy of wild-type spike protein nanoparticle (S-2P) and mutant spike protein nanoparticle (S-4M-2P) carrying characteristic mutations of B.1.351 variant in mice. Although there was no significant difference in the induction of spike-specific IgG responses in S-2P- and S-4M-2P-immunized mice, neutralizing antibodies elicited by S-4M-2P exhibited noteworthy, narrower breadth of reactivity with SARS-CoV-2 variants compared with neutralizing antibodies elicited by S-2P. Furthermore, the decrease of induced neutralizing antibody breadth at least partly resulted from the amino acid substitution at position 484. Moreover, S-4M-2P vaccination conferred insufficient protection against live SARS-CoV-2 virus infection, while S-2P vaccination gave definite protection against SARS-CoV-2 challenge in mice. Together, our study provides direct evidence that the E484K substitution in a SARS-CoV-2 subunit protein vaccine limited the cross-reactive neutralizing antibody breadth in mice and, more importantly, draws attention to the unfavorable impact of this mutation in spike protein of SARS-CoV-2 variants on the induction of potent neutralizing antibody responses.

SARS-CoV-2 Omicron Variant is Expected to Retain Most of the Spike Protein Specific Dominant T-Cell Epitopes Presented by COVID-19 Vaccines - Worldwide, 2021.

What is already known about this topic?: The newly emerged variant of Omicron, which carries many of the mutations found in other variants of concern (VOCs), as well as a great number of new mutations that may enhance its immune escape, has spread rapidly around the world. This has raised public concern about the effectiveness of the current coronavirus disease 2019 (COVID-19) vaccine. What is added by this report?: In this study, different bioinformatic softwares were applied to predict the dominant Omicron spike (S) protein cytotoxic T lymphocyte (CTL) and T helper (Th) epitopes in representative world population and Chinese population. Compared to the original severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S protein, limited mutations were identified within the dominant CTL and Th epitopes in Omicron variant. What are the implications for public health practice?: The results of this study suggested that the current COVID-19 vaccine-induced T-cell immunity may still provide significant protection against Omicron variant infection in fully vaccinated individuals.

Effect of the COVID-19 Pandemic on Consumers' Impulse Buying: The Moderating Role of Moderate Thinking.

Based on event systems theory, this study examined the impact of the COVID-19 pandemic on consumers' impulse buying, as well as the underlying mechanisms and boundary conditions from the perspective of individual consumers. Results of three experiments (N = 437) show that, first, the COVID-19 pandemic enhanced consumers' impulse buying behavior. Second, two key elements, loss of control and anxiety, mediated the relationship between the COVID-19 pandemic and impulse buying; and third, moderate thinking (also known as Zhong-Yong thinking) moderated the relationship between the COVID-19 pandemic and impulse buying. The findings indicate that in consumers with low moderate thinking, the COVID-19 pandemic has had a stronger effect on impulse buying and has mediated more between the loss of control and anxiety. Conversely, in consumers with high moderate thinking, COVID-19 has had a weaker effect on impulse buying and has mediated less between loss of control and anxiety. This study extends the application of event systems theory and enriches the literature on how the COVID-19 pandemic affects consumer behavior. Furthermore, it provides strategic recommendations for government and consumer responses to COVID-19 pandemic shocks.

Intranasal administration of a recombinant RBD vaccine induced protective immunity against SARS-CoV-2 in mouse.

The emergence of the global Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic underscores the importance of the rapid development of a non-invasive vaccine that can be easily administered. A vaccine administered by nasal delivery is endowed with such characteristics against respiratory viruses. In this study, we generated a recombinant SARS-CoV-2 receptor-binding domain (RBD)-based subunit vaccine. Mice were immunized via intranasal inoculation, microneedle-intradermal injection, or intramuscular injection, after which the RBD-specific immune responses were compared. Results showed that when administrated intranasally, the vaccine elicited a robust systemic humoral immunity with high titers of IgG antibodies and neutralizing antibodies as well as a significant mucosal immunity. Besides, antigen-specific T cell responses were also analyzed. These results indicated that the non-invasive intranasal administration should be explored for the future SARS-CoV-2 vaccine design.

Engineering a Reliable and Convenient SARS-CoV-2 Replicon System for Analysis of Viral RNA Synthesis and Screening of Antiviral Inhibitors.

The etiologic agent of COVID-19 is highly contagious and has caused a severe global pandemic. Until now, there has been no simple and reliable system available in a lower-biosafety-grade laboratory for SARS-CoV-2 virologic research and inhibitor screening. In this study, we reported a replicon system which consists of four plasmids expressing the required segments of SARS-CoV-2. Our study revealed that the features for viral RNA synthesis and responses to antivirus drugs of the replicon are similar to those of wild-type viruses. Further analysis indicated that ORF6 provided potent in trans stimulation of the viral replication. Some viral variations, such as 5'UTR-C241T and ORF8-(T28144C) L84S mutation, also exhibit their different impact upon viral replication. Besides, the screening of clinically used drugs identified that several tyrosine kinase inhibitors and DNA-Top II inhibitors potently inhibit the replicon, as well as authentic SARS-CoV-2 viruses. Collectively, this replicon system provides a biosafety-worry-free platform for studying SARS-CoV-2 virology, monitoring the functional impact of viral mutations, and developing viral inhibitors.IMPORTANCE COVID-19 has caused a severe global pandemic. Until now, there has been no simple and reliable system available in a lower-biosafety-grade laboratory for SARS-CoV-2 virologic research and inhibitor screening. We reported a replicon system which consists of four ordinary plasmids expressing the required segments of SARS-CoV-2. Using the replicon system, we developed three application scenarios: (i) to identify the effects of viral proteins on virus replication, (ii) to identify the effects of mutations on viral replication during viral epidemics, and (iii) to perform high-throughput screening of antiviral drugs. Collectively, this replicon system would be useful for virologists to study SARS-CoV-2 virology, for epidemiologists to monitor virus mutations, and for industry to develop antiviral drugs.

A false alarm of COVID-19 pneumonia in lung cancer with anti-PD-1 related pneumonitis: a case report and review of the literature.

BACKGROUND: Pneumonitis belongs to the fatal toxicities of anti-PD-1/PD-L1 treatments. Its diagnosis is based on immunotherapeutic histories, clinical symptoms, and the computed tomography (CT) imaging. The radiological features were typically ground-glass opacities, similar to CT presentation of 2019 Novel Coronavirus (COVID-19) pneumonia. Thus, clinicians are cautious in differential diagnosis especially in COVID-19 epidemic areas. CASE PRESENTATION: Herein, we report a 67-year-old Han Chinese male patient presenting with dyspnea and normal body temperature on the 15th day of close contact with his son, who returned from Wuhan. He was diagnosed as advanced non-small cell lung cancer and developed pneumonitis post Sintilimab injection during COIVD-19 pandemic period. The chest CT indicated peripherally subpleural lattice opacities at the inferior right lung lobe and bilateral thoracic effusion. The swab samples were taken twice within 72 hours and real-time reverse-transcription polymerase-chain-reaction (RT-PCR) results were COVID-19 negative. The patient was thereafter treated with prednisolone and antibiotics for over 2 weeks. The suspicious lesion has almost absorbed according to CT imaging, consistent with prominently falling CRP level. The anti-PD-1 related pneumonitis mixed with bacterial infection was clinically diagnosed based on the laboratory and radiological evidences and good response to the prednisolone and antibiotics. CONCLUSION: The anti-PD-1 related pneumonitis and COVID-19 pneumonia possess similar clinical presentations and CT imaging features. Therefore, differential diagnosis depends on the epidemiological and immunotherapy histories, RT-PCR tests. The response to glucocorticoid is still controversial but helpful for the diagnosis.