Human coronaviruses 229E and OC43 replicate and induce distinct antiviral responses in differentiated primary human bronchial epithelial cells.

The recurrent emergence of novel, pathogenic coronaviruses (CoVs) severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1; 2002), Middle East respiratory syndrome (MERS)-CoV (2012), and most recently SARS-CoV-2 (2019) has highlighted the need for physiologically informative airway epithelial cell infection models for studying immunity to CoVs and development of antiviral therapies. To address this, we developed an in vitro infection model for two human coronaviruses; alphacoronavirus 229E-CoV (229E) and betacoronavirus OC43-CoV (OC43) in differentiated primary human bronchial epithelial cells (pBECs). Primary BECs from healthy subjects were grown at air-liquid interface (ALI) and infected with 229E or OC43, and replication kinetics and time-course expression of innate immune mediators were assessed. OC43 and 229E-CoVs replicated in differentiated pBECs but displayed distinct replication kinetics: 229E replicated rapidly with viral load peaking at 24 h postinfection, while OC43 replication was slower peaking at 96 h after infection. This was associated with diverse antiviral response profiles defined by increased expression of type I/III interferons and interferon-stimulated genes (ISGs) by 229E compared with no innate immune activation with OC43 infection. Understanding the host-virus interaction for previously established coronaviruses will give insight into pathogenic mechanisms underpinning SARS-CoV-2-induced respiratory disease and other future coronaviruses that may arise from zoonotic sources.

Neutralizing and binding activities against SARS-CoV-1/2, MERS-CoV, and human coronaviruses 229E and OC43 by normal human intravenous immunoglobulin derived from healthy donors in Japan.

BACKGROUND: There are several types of coronaviruses that infect humans and cause disease. The latest is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is an emerging global threat with no current effective treatment. Normal intravenous immunoglobulin (N-IVIG) has been administered to coronavirus disease 2019 (COVID-19) patients to control severe inflammation and the cellular immune response. However, the neutralizing activity of N-IVIG against SARS-CoV-2 has not yet been fully evaluated. The aim of this study was to determine whether N-IVIG manufactured before the start of the COVID-19 pandemic contained IgG antibodies against the circulating human coronaviruses (HCoVs) that cross-react with the highly pathogenic coronaviruses SARS-CoV-1, Middle East respiratory syndrome coronavirus (MERS-CoV), and SARS-CoV-2. No cases of SARS-CoV-1 or MERS-CoV have been reported in Japan. STUDY DESIGN AND METHODS: The neutralizing and binding activities of N-IVIG against SARS-CoV-1, MERS-CoV, SARS-CoV-2, HCoV 229E, and HCoV OC43 were evaluated. Nine N-IVIG lots manufactured between 2000 and 2018, derived from donors in Japan, were tested. Binding activity was evaluated by indirect immunofluorescence assay. RESULTS: None of the N-IVIG lots tested displayed neutralizing or binding activity against SARS-CoV-1, MERS-CoV, or SARS-CoV-2. However, they displayed substantial neutralizing and binding activity against HCoV OC43 and weak neutralizing and substantial binding activity against HCoV 229E. CONCLUSION: N-IVIG derived from healthy donors in Japan before the start of the COVID-19 pandemic had no direct effect against SARS-CoV-2. Further studies are warranted to determine the effects of N-IVIG manufactured after the start of the COVID-19 pandemic against SARS-CoV-2.

SARS-CoV-2-reactive T cells in healthy donors and patients with COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the rapidly unfolding coronavirus disease 2019 (COVID-19) pandemic1,2. Clinical manifestations of COVID-19 vary, ranging from asymptomatic infection to respiratory failure. The mechanisms that determine such variable outcomes remain unresolved. Here we investigated CD4+ T cells that are reactive against the spike glycoprotein of SARS-CoV-2 in the peripheral blood of patients with COVID-19 and SARS-CoV-2-unexposed healthy donors. We detected spike-reactive CD4+ T cells not only in 83% of patients with COVID-19 but also in 35% of healthy donors. Spike-reactive CD4+ T cells in healthy donors were primarily active against C-terminal epitopes in the spike protein, which show a higher homology to spike glycoproteins of human endemic coronaviruses, compared with N-terminal epitopes. Spike-protein-reactive T cell lines generated from SARS-CoV-2-naive healthy donors responded similarly to the C-terminal region of the spike proteins of the human endemic coronaviruses 229E and OC43, as well as that of SARS-CoV-2. This results indicate that spike-protein cross-reactive T cells are present, which were probably generated during previous encounters with endemic coronaviruses. The effect of pre-existing SARS-CoV-2 cross-reactive T cells on clinical outcomes remains to be determined in larger cohorts. However, the presence of spike-protein cross-reactive T cells in a considerable fraction of the general population may affect the dynamics of the current pandemic, and has important implications for the design and analysis of upcoming trials investigating COVID-19 vaccines.