Bovine lactoferrin inhibits SARS-CoV-2 and SARS-CoV-1 by targeting the RdRp complex and alleviates viral infection in the hamster model.

Breast milk has been found to inhibit coronavirus infection, while the key components and mechanisms are unknown. We aimed to determine the components that contribute to the antiviral effects of breastmilk and explore their potential mechanism. Lactoferrin (Lf) and milk fat globule membrane (MFGM) inhibit SARS-CoV-2 related coronavirus GX_P2V and SARS-CoV-2 trVLP in vitro and block viral entry into cells. We confirmed that bovine lactoferrin (bLf) blocked the binding between human angiotensin-converting enzyme 2 (hACE2) and SARS-CoV-2 spike protein by combining receptor binding domain (RBD). Importantly, bLf inhibited RNA-dependent RNA polymerase (RdRp) activity of both SARS-CoV-2 and SARS-CoV in vitro in the nanomolar range. So far, no biological macromolecules have been reported to inhibit coronavirus RdRp. Our result indicated that bLf plays a major role in inhibiting viral replication rather than viral entry, which has been widely explored. bLf treatment reduced viral load in lungs and tracheae and alleviated pathological damage. Our study provides evidence that bLf prevents SARS-CoV-2 infection by combining SARS-CoV-2 spike protein RBD and inhibiting coronaviruses' RdRp activity, and may be a promising candidate for the treatment of COVID-19. This article is protected by copyright. All rights reserved.

2'-Fucosyllactose Inhibits Coxsackievirus Class A Type 9 Infection by Blocking Virus Attachment and Internalisation.

Coxsackieviruses, a genus of enteroviruses in the small RNA virus family, cause fatal infectious diseases in humans. Thus far, there are no approved drugs to prevent these diseases. Human milk contains various biologically active components against pathogens. Currently, the potential activity of breast milk components against the coxsackievirus remains unclear. In our study, the inhibitory effect of 16 major human milk components was tested on coxsackievirus class A type 9 isolate (CV-A9), BUCT01; 2'-Fucosyllactose (2'-FL) was identified to be effective. Time-of-addition, attachment internalisation assays, and the addition of 2'-FL at different time points were applied to investigate its specific role in the viral life cycle. Molecular docking was used to predict 2'-FL's specific cellular targets. The initial screening revealed a significant inhibitory effect (99.97%) against CV-A9 with 10 mg/mL 2'-FL, with no cytotoxicity observed. Compared with the control group, 2'-FL blocked virus entry (85%) as well as inhibited viral attachment (48.4%) and internalisation (51.3%), minimising its infection in rhabdomyosarcoma (RD) cells. The cell pre-incubation with 2'-FL exhibited significant inhibition (73.2-99.9%). Extended incubation between cells with 2'-FL reduced CV-A9 infection (93.9%), suggesting that 2'-FL predominantly targets cells to block infection. Molecular docking results revealed that 2'-FL interacted with the attachment receptor αvß6 and the internalisation receptor FCGRT and ß2M with an affinity of -2.14, -1.87, and -5.43 kcal/mol, respectively. This study lays the foundation for using 2'-FL as a food additive against CV-A9 infections.

Antiviral Drugs Screening for Swine Acute Diarrhea Syndrome Coronavirus.

Coronaviruses as possible cross-species viruses have caused several epidemics. The ongoing emergency of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has posed severe threats to the global economy and public health, which has generated great concerns about zoonotic viruses. Swine acute diarrhea syndrome coronavirus (SADS-CoV), an alpha-coronavirus, was responsible for mass piglet deaths, resulting in unprecedented economic losses, and no approved drugs or vaccines are currently available for SADS-CoV infection. Given its potential ability to cause cross-species infection, it is essential to develop specific antiviral drugs and vaccines against SADS-CoV. Drug screening was performed on a total of 3523 compound-containing drug libraries as a strategy of existing medications repurposing. We identified five compounds (gemcitabine, mycophenolate mofetil, mycophenolic acid, methylene blue and cepharanthine) exhibiting inhibitory effects against SADS-CoV in a dose-dependent manner. Cepharanthine and methylene blue were confirmed to block viral entry, and gemcitabine, mycophenolate mofetil, mycophenolic acid and methylene blue could inhibit viral replication after SADS-CoV entry. This is the first report on SADS-CoV drug screening, and we found five compounds from drug libraries to be potential anti-SADS-CoV drugs, supporting the development of antiviral drugs for a possible outbreak of SADS-CoV in the future.

Overview of Breastfeeding Under COVID-19 Pandemic.

During the global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), pregnant and lactating women are at higher risk of infection. The potential of viral intrauterine transmission and vertical transmission by breastfeeding has raised wide concerns. Breastmilk is rich in nutrients that contribute to infant growth and development, and reduce the incidence rate of infant illness and death, as well as inhibit pathogens significantly, and protect infants from infection. Although it is controversial whether mothers infected with COVID-19 should continue to breastfeed, many countries and international organizations have provided recommendations and guidance for breastfeeding. This review presents the risks and benefits of breastfeeding for mothers infected with COVID-19, and the reasons for the absence of SARS-CoV-2 active virus in human milk. In addition, the antiviral mechanisms of nutrients in breastmilk, the levels of SARS-CoV-2 specific antibodies in breastmilk from COVID-19 infected mothers and vaccinated mothers are also summarized and discussed, aiming to provide some support and recommendations for both lactating mothers and infants to better deal with the COVID-19 pandemic.

Transcriptome analysis of cepharanthine against a SARS-CoV-2-related coronavirus.

Antiviral therapies targeting the pandemic coronavirus disease 2019 (COVID-19) are urgently required. We studied an already-approved botanical drug cepharanthine (CEP) in a cell culture model of GX_P2V, a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related virus. RNA-sequencing results showed the virus perturbed the expression of multiple genes including those associated with cellular stress responses such as endoplasmic reticulum (ER) stress and heat shock factor 1 (HSF1)-mediated heat shock response, of which heat shock response-related genes and pathways were at the core. CEP was potent to reverse most dysregulated genes and pathways in infected cells including ER stress/unfolded protein response and HSF1-mediated heat shock response. Additionally, single-cell transcriptomes also confirmed that genes of cellular stress responses and autophagy pathways were enriched in several peripheral blood mononuclear cells populations from COVID-19 patients. In summary, this study uncovered the transcriptome of a SARS-CoV-2-related coronavirus infection model and anti-viral activities of CEP, providing evidence for CEP as a promising therapeutic option for SARS-CoV-2 infection.

Ubiquitin-Modified Proteome of SARS-CoV-2-Infected Host Cells Reveals Insights into Virus-Host Interaction and Pathogenesis.

The outbreak of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a serious threat to global public health. The mechanism of pathogenesis and the host immune response to SARS-CoV-2 infection are largely unknown. In the present study, we applied a quantitative proteomic technology to identify and quantify the ubiquitination changes that occur in both the virus and the Vero E6 cells during SARS-CoV-2 infection. By applying label-free, quantitative liquid chromatography with tandem mass spectrometry proteomics, 8943 lysine ubiquitination sites on 3086 proteins were identified, of which 138 sites on 104 proteins were quantified as significantly upregulated, while 828 sites on 447 proteins were downregulated at 72 h post-infection. Bioinformatics analysis suggested that SARS-CoV-2 infection might modulate host immune responses through the ubiquitination of important proteins, including USP5, IQGAP1, TRIM28, and Hsp90. Ubiquitination modification was also observed on 11 SAR-CoV-2 proteins, including proteins involved in virus replication and inhibition of the host innate immune response. Our study provides new insights into the interaction between SARS-CoV-2 and the host as well as potential targets for the prevention and treatment of COVID-19.