Immune response and potential therapeutic strategies for the SARS-CoV-2 associated with the COVID-19 pandemic

Plant-derived strategies to fight against severe acute respiratory syndrome coronavirus 2

The coronavirus disease 2019 (COVID-19) pandemic has caused an unprecedented crisis, which has been exacerbated because specific drugs and treatments have not yet been developed. In the post-pandemic era, humans and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will remain in equilibrium for a long time. Therefore, we still need to be vigilant against mutated SARS-CoV-2 variants and other emerging human viruses. Plant-derived products are increasingly important in the fight against the pandemic, but a comprehensive review is lacking. This review describes plant-based strategies centered on key biological processes, such as SARS-CoV-2 transmission, entry, replication, and immune interference. We highlight the mechanisms and effects of these plant-derived products and their feasibility and limitations for the treatment and prevention of COVID-19. The development of emerging technologies is driving plants to become production platforms for various antiviral products, improving their medicinal potential. We believe that plant-based strategies will be an important part of the solutions for future pandemics.

The role of SARS-CoV-2 accessory proteins in immune evasion

Many questions on the SARS-CoV-2 pathogenesis remain to answer. The SARS-CoV-2 genome encodes some accessory proteins that are essential for infection. Notably, accessory proteins of SARS-CoV-2 play significant roles in affecting immune escape and viral pathogenesis. Therefore SARS-CoV-2 accessory proteins could be considered putative drug targets. IFN-I and IFN-III responses are the primary mechanisms of innate antiviral immunity in infection clearance. Previous research has shown that SARS-CoV-2 suppresses IFN-β by infecting host cells via ORF3a, ORF3b, ORF6, ORF7a, ORF7b, ORF8, and ORF9b. Furthermore, ORF3a, ORF7a, and ORF7b have a role in blocking IFNα signaling, and ORF8 represses IFNβ signaling. The ORF3a, ORF7a, and ORF7b disrupt the STAT1/2 phosphorylation. ORF3a, ORF6, ORF7a, and ORF7b could prevent the ISRE promoter activity. The main SARS-CoV-2 accessory proteins involved in immune evasion are discussed here for comprehensive learning on viral entry, replication, and transmission in vaccines and antiviral development.

Post acute CoViD-19 syndrome (PACS) - Long CoViD

Patients sero-positive for the Systemic Acute Respiratory Syndrome Corona virus2 (SARS-CoV2) virus develop the Corona Virus Disease 2019 (CoViD-19). CoViD-19 may be asymptomatic in some individuals, proffer mild symptoms in other patients, and can be a serious and even lethal disease in a sub-group of the population. The variables that determine the severity of CoViD-19 have not been fully characterized. What is clear is that the patients who survive CoViD-19 return to a state of sero-negativity for SARS-CoV2 generally within 3-5 weeks. However, several cases of repeated infection have been reported, and a large proportion of CoViD-19-recovered patients manifest multi-system and multi-organ symptomatic pathologies several weeks-to-months after resuming sero-negativity for SARS-CoV2. This new pathological condition, originally termed Long Covid, is now recognized as the Post Acute CoViD-19 Syndrome (PACS). The original principal clusters of signs and symptoms of PACS: likelihood of relapse and reinfection, physical fatigue and cognitive slowdown, may actually be broadened to include immune deregulation, cardiovascular disease and coagulation abnormalities. The development and evaluation of new and improved clinical interventions for PACS are critical and timely.

Prospects of Coffee Leaf against SARS-CoV-2 Infection

In the current climate, many countries are in dire need of effective preventive methods to curb the Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2) pandemic. The purpose of this research is to screen and explore natural plant extracts that have the potential to against SARS-CoV-2 and provide alternative options for SARS-CoV-2 prevention and hand sanitizer or spray-like disinfectants. We first used Spike-ACE2 ELISA and TMPRSS2 fluorescence resonance energy transfer (FRET) assays to screen extracts from agricultural by-products from Taiwan with the potential to impede SARS-CoV-2 infection. Next, the SARS-CoV-2 pseudo-particles (Vpp) infection assay was tested to validate the effectiveness. We identified an extract from coffee leaf (Coffea Arabica), a natural plant that effectively inhibited wild-type SARS-CoV-2, and five Variants of Concern (Alpha, Beta, Gamma, Delta, and Omicron strain) from entering host cells. In an attempt to apply coffee leaf extract for hand sanitizer or spray-like disinfectants, we designed a skin-like gelatin membrane experiment. We showed that the high concentration of coffee leaf extract on the skin surface could block SARS-CoV-2 into cells more potently than 75% Ethanol, a standard disinfectant to inactivate SARS-CoV-2. Finally, LC-HRMS analysis was used to identify compounds such as caffeine, chlorogenic acid (CGA), quinic acid, and mangiferin that are associated with an anti-SARS-CoV-2 activity. Our results demonstrated that coffee leaf extract, an agricultural by-product effectively inhibits SARS-CoV-2 Vpp infection through an ACE2-dependent mechanism and may be utilized to develop products against SARS-CoV-2 infection.

Immune Cells Profiles In The Peripheral Blood Of Patients With Moderate To Severe COVID-19 And Healthy Subjects With and Without Vaccination With The Pfizer-BioNTech mRNA Vaccine

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus disease 2019 (COVID-19), has caused a global crisis. Patients with COVID-19 present with a range of clinical manifestations, from no symptoms to severe illness. However, little is known about the profiles of immune cells required to protect against SARS-CoV-2. This study was performed to determine the immune cells profiles in the peripheral blood of COVID-19 patients with moderate to severe disease (n=52), and compare the findings with those from healthy subjects vaccinated with Pfizer BioNTech mRNA vaccine (VS) (n=62), and non-vaccinated healthy subjects (HS) (n=30) from Kuwait. Absolute counts and percentages of total lymphocytes and lymphocyte subsets (CD3+ T cells, CD4+ T cells, CD8+ T cells, CD19+ B cells, and CD16+CD56+ NK cells) in the peripheral blood of the three groups were analyzed using flow cytometry. The results showed that the absolute counts of total lymphocytes, CD3+, CD4+, and CD8+ T cells, CD19+ B cells, and CD56+ NK cells, were significantly lower in COVID-19 patients than normal healthy controls and vaccinated subjects. The percentages of CD3+ and CD4+ T lymphocytes were also significantly lower in the COVID-19 patients. However, the percentage of CD16+CD56+ NK cells was significantly higher in the peripheral blood of COVID-19 patients, compared to the HS and VS groups with no detectable differences in the percentages of CD8+ T cells and CD19+ B cells between the three groups. Analysis of the monocyte subsets has showed a significantly higher percentage of CD14+HLA-DR+ monocytes in COVID-19 patients compared to HS whereas the inflammatory CD14+CD16+ HLA-DR+ monocytes, and the non-classical CD16+HLA-DR+ monocytes showed significantly lower frequency in the blood of the patients than that of HS. These findings demonstrate perturbations of both innate and adaptive immune cell subsets that reflect dysregulated host responses in COVID-19 patients with moderate to severe disease.

Innate Immune Responses by Respiratory Viruses, Including Rhinovirus, During Asthma Exacerbation

Viral infection, especially with rhinovirus (RV), is a major cause of asthma exacerbation. The production of anti-viral cytokines such as interferon (IFN)-β and IFN-α from epithelial cells or dendritic cells is lower in patients with asthma or those with high IgE, which can contribute to viral-induced exacerbated disease in these patients. As for virus-related factors, RV species C (RV-C) induces more exacerbated disease than other RVs, including RV-B. Neutrophils activated by viral infection can induce eosinophilic airway inflammation through different mechanisms. Furthermore, virus-induced or virus-related proteins can directly activate eosinophils. For example, CXCL10, which is upregulated during viral infection, activates eosinophils in vitro. The role of innate immune responses, especially type-2 innate lymphoid cells (ILC2) and epithelial cell-related cytokines including IL-33, IL-25, and thymic stromal lymphopoietin (TSLP), in the development of viral-induced airway inflammation has recently been established. For example, RV infection induces the expression of IL-33 or IL-25, or increases the ratio of ILC2 in the asthmatic airway, which is correlated with the severity of exacerbation. A mouse model has further demonstrated that virus-induced mucous metaplasia and ILC2 expansion are suppressed by antagonizing or deleting IL-33, IL-25, or TSLP. For treatment, IFNs including IFN-β suppress not only viral replication but also ILC2 activation in vitro. Agonists of toll-like receptor (TLR) 3 or 7 can induce IFNs, which can then suppress viral replication and ILC2 activation. Therefore, if delivered in the airway, IFNs or TLR agonists could become innovative treatments for virus-induced asthma exacerbation.