The coronavirus disease 2019 (COVID-19) pandemic with high infectivity and mortality has caused severe social and economic impacts worldwide. Growing reports of COVID-19 patients with multi-organ damage indicated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) may also disturb the cardiovascular system. Herein, we used human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMs) as the in vitro platform to examine the consequence of SARS-CoV2 infection on iCMs. Differentiated iCMs expressed the primary SARS-CoV2 receptor angiotensin-converting enzyme-II (ACE2) and the transmembrane protease serine type 2 (TMPRSS2) receptor suggesting the susceptibility of iCMs to SARS-CoV2. Following the infection of iCMs with SARS-CoV2, the viral nucleocapsid (N) protein was detected in the host cells, demonstrating the successful infection. Bioinformatics analysis revealed that the SARS-CoV2 infection upregulates several inflammation-related genes, including the proinflammatory cytokine tumor necrosis factor-α (TNF-α). The pretreatment of iCMs with TNF-α for 24 h, significantly increased the expression of ACE2 and TMPRSS2, SASR-CoV2 entry receptors. The TNF-α pretreatment enhanced the entry of GFP-expressing SARS-CoV2 pseudovirus into iCMs, and the neutralization of TNF-α ameliorated the TNF-α-enhanced viral entry. Collectively, SARS-CoV2 elevated TNF-α expression, which in turn enhanced the SARS-CoV2 viral entry. Our findings suggest that, TNF-α may participate in the cytokine storm and aggravate the myocardial damage in COVID-19 patients.

(Background) The coronavirus disease 2019 (COVID-19) that is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) carries high infectivity and mortality. Efficient intervention strategies are urgently needed. Avian immunoglobulin Y (IgY) showed efficacy against viral infection whereas the in vivo efficacy remains unclear. (Methods) We immunized laying hens with S1, S1 receptor-binding domain (S1-RBD), or S2 subunits of the SARS-CoV-2 spike (S) protein. After immunization, IgYs were collected and extracted from the egg yolks. The neutralization potential of IgYs was examined by the plaque reduction neutralization test (PRNT). The bioutility of IgYs was examined in Syrian hamsters in vivo. (Results) IgYs exhibited typical banding patterns in SDS-PAGE and Western blot and were immunoreactive against S1, S1-RBD, and S2 subunits. The plaque reduction neutralization test (PRNT) showed that all purified IgYs potently neutralized different SARS-CoV-2 strains in vitro. In Syrian hamsters, the combination of IgYs for S1-RBD and S2 subunits administered before or after SARS-CoV-2 infection effectively restored body weight loss and reduced intrapulmonary lesions and the amount of immunoreactive N protein-positive cells, which were caused by SARS-CoV-2 infection. (Conclusions) Collectively, IgYs specific for S protein subunits effectively neutralized SARS-CoV-2 in vitro and in vivo and may serve as prophylactic or therapeutic antibodies in the prevention or treatment of COVID-19.

The rapid mutation rate of SARS-CoV-2 highlights the urgent need for continuous drug development to enhance both efficacy and safety. BPR2-D2, an angular coumarin derivative, has previously shown notable anti-influenza activity and broad-spectrum inhibitory effects against RNA viruses. In this study, we found that BPR2-D2 exhibits potent antiviral activity against multiple SARS-CoV-2 variants, including several variants of concern, at nanomolar concentrations. Notably, BPR2-D2 effectively disrupted viral RNA and protein synthesis in infected cells while mitigating pro-inflammatory cytokines triggered by viral replication. Our investigation of SARS-CoV-2 RdRp activity employed in silico analyses, including molecular docking, dynamic simulations, and binding free energy calculations. BPR2-D2 demonstrated superior binding affinity to the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 compared to remdesivir. Additionally, it exhibited an increased synergistic inhibitory activity against the viral enzyme when combined with remdesivir. Both cell-based and in vitro enzyme-based RdRp reporter assays validated BPR2-D2's capacity to inhibit SARS-CoV-2 RdRp activity. The potential synergistic interaction between BPR2-D2 and remdesivir was investigated using cell-based combination assays. The results revealed a synergistic effect in reducing SARS-CoV-2 RNA synthesis, consistent with the in silico analysis. Collectively, these findings suggest that BPR2-D2, a repurposed small-molecule compound, effectively inhibits SARS-CoV-2 by modulating its RdRp function. This positions BPR2-D2 as a promising novel antiviral agent, while also providing insights into the complex molecular mechanisms underlying viral replication.