Overview of Immune Response During SARS-CoV-2 Infection: Lessons From the Past

Spike is the most recognized antigen in the whole-blood platform in both acute and convalescent COVID-19 patients

OBJECTIVES

To identify the best experimental approach to detect a SARS-CoV-2-specific T cell response using a whole-blood platform.

METHODS

Whole-blood from 56 COVID-19 and 23 "NO-COVID-19" individuals were stimulated overnight with different concentrations (0.1 or 1 μg/mL) of SARS-CoV-2 PepTivator® Peptide Pools, including spike (pool S), nucleocapsid (pool N), membrane (pool M), and a MegaPool (MP) of these three peptide pools. ELISA was used to analyse interferon (IFN)-γ levels.

RESULTS

The IFN-γ-response to every SARS-CoV-2 peptide pool was significantly increased in COVID-19 patients compared with NO-COVID-19 individuals. Pool S and MegaPool were the most potent immunogenic stimuli (median: 0.51, IQR: 0.14-2.17; and median: 1.18, IQR: 0.27-4.72, respectively) compared with pools N and M (median: 0.22, IQR: 0.032-1.26; and median: 0.22, IQR: 0.01-0.71, respectively). The whole-blood test based on pool S and MegaPool showed a good sensitivity of 77% and a high specificity of 96%. The IFN-γ-response was mediated by both CD4⁺ and CD8⁺ T cells, and independently detected of clinical parameters in both hospitalized and recovered patients.

CONCLUSIONS

This easy-to-use assay for detecting SARS-CoV-2-specific T cell responses may be implemented in clinical laboratories as a powerful diagnostic tool.

Experimental Animal Models of Coronavirus Infections: Strengths and Limitations

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the emergence of SARS-CoV-2 in the human population in late 2019, it has spread on an unprecedented scale worldwide leading to the first coronavirus pandemic. SARS-CoV-2 infection results in a wide range of clinical manifestations from asymptomatic to fatal cases. Although intensive research has been undertaken to increase understanding of the complex biology of SARS-CoV-2 infection, the detailed mechanisms underpinning the severe pathogenesis and interactions between the virus and the host immune response are not well understood. Thus, the development of appropriate animal models that recapitulate human clinical manifestations and immune responses against SARS-CoV-2 is crucial. Although many animal models are currently available for the study of SARS-CoV-2 infection, each has distinct advantages and disadvantages, and some models show variable results between and within species. Thus, we aim to discuss the different animal models, including mice, hamsters, ferrets, and non-human primates, employed for SARS-CoV-2 infection studies and outline their individual strengths and limitations for use in studies aimed at increasing understanding of coronavirus pathogenesis. Moreover, a significant advantage of these animal models is that they can be tailored, providing unique options specific to the scientific goals of each researcher.

COVID-19 or Influenza, or Both? A Comparison and Algorithmic Approach to Management

Context: First cases of Coronavirus disease 2019 (COVID-19) were reported in December 2019. With more than 100 million confirmed cases 14 months later, the disease has become the worst public-health dilemma of the century. The rapid global spread of COVID-19 has resulted in an international health emergency, threatening to overwhelm health care systems in many parts of the world, especially poor resource countries. Evidence Acquisition: Influenza and COVID-19 have similar clinical symptoms, and both cause a respiratory illness that may vary from mild to severe. Both diseases have the same mode of transmission and require similar public health guidelines to prevent their spread, but their treatment strategies are different. In this study, an algorithmic method is proposed for managing patients according to their symptoms for each of these infections. Results: In fall and winter, infections with seasonal influenza and other respiratory viruses become common. As influenza also causes significant morbidity and mortality, especially at the two extremes of age and in those with compromised immunity, it is of major importance to know the similarities and dissimilarities between COVID-19 and seasonal influenza and plan appropriate public health measures to deal with each of these illnesses. Conclusions: Will there be a devastating combined epidemic of COVID-19 and influenza (COV-Flu) during the 2020 - 2021 season? Does co-infection increase the risk of severe illness or amplify virus shedding? Actually, we do not yet know the answers to these questions; so, in this article, first, we attempt to define the similarities and differences between COV-Flu. Then, we will have a brief discussion on how to manage patients presenting with symptoms suggestive of both diseases. However, as COVID-19 has been recognized as a pandemic since December 2019, the management of this emerging disease is rapidly evolving as new information is collected from different parts of the world.

COVID-19 co-infection mathematical model as guided through signaling structural framework

SARS-CoV-2 and Influenza co-infection turned out to be a huge threat in recent times. The clinical presentation and disease severity is common in both the infection condition. The present paper deals with studying co-infection model system through systems biology approaches. Understanding signaling regulation in COVID-19 and co-infection model systems aid in the development of network-based models thereby suggesting intervention points for therapeutics. This paper highlights the aim of revealing such perturbations to decipher opportune mediating cross talks characterizing the deadly viral disease. The comparative analysis of both the models reveals major signaling protein NFκB and STAT1 playing a crucial role in establishing co-infection. By targeting these proteins at cellular level, it might help modulating the release of potent pro-inflammatory cytokines thereby taming the severity of the disease symptoms. Mathematical models developed here are precisely tailored and serves as a first step towards co-infection model offering flexibility and pitching towards therapeutic investigation.

Diabetes, inflammation, and the adiponectin paradox: Therapeutic targets in SARS-CoV-2

Aging and pre-existing conditions in older patients increase severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) severity and its complications, although the causes remain unclear. Apart from acute pulmonary syndrome, Coronavirus 2019 (COVID-19) can increasingly induce chronic conditions. Importantly, SARS-CoV-2 triggers de novo type 2 diabetes mellitus (T2DM) linked to age-associated cardiovascular disease (CVD), cancers, and neurodegeneration. Mechanistically, SARS-CoV-2 induces inflammation, possibly through damage-associated molecular pattern (DAMP) signaling and ‘cytokine storm,’ causing insulin resistance and the adiponectin (APN) paradox, a phenomenon linking metabolic dysfunction to chronic disease. Accordingly, preventing the APN paradox by suppressing APN-related inflammatory signaling might prove beneficial. A better understanding could uncover novel therapies for SARS-CoV-2 and its chronic disorders.

Structure insights of SARS-CoV-2 open state envelope protein and inhibiting through active phytochemical of ayurvedic medicinal plants from Withania somnifera

Coronaviruses have been causing pandemic situations across the globe for the past two decades and the focus is on identifying suitable novel targets for antivirals and vaccine development. SARS-CoV-2 encodes a small hydrophobic envelope (E) protein that mediates envelope formation, budding, replication, and release of progeny viruses from the host. Through this study, the SARS-CoV-2 E protein is studied for its open and closed state and focused in identifying antiviral herbs used in traditional medicine practices for COVID-19 infections. In this study using computational tools, we docked the shortlisted phytochemicals with the envelope protein of the SARS-CoV-2 virus and the results hint that these compounds interact with the pore-lining residues. The molecular level understanding of the open state is considered and the active inhibitors from the phytochemicals of Ayurvedic medicinal plants from Withania somnifera. We have thus identified a potential phytochemical compound that directly binds with the pore region of the E protein and thereby blocks its channel activity. Blocking the ion channel activity of E protein is directly related to the inhibition of virus replication. The study shows encouraging results on the usage of these phytochemicals in the treatment/management of SARS-CoV-2 infection.

Global epidemiology of coronavirus disease 2019 and lessons for effective control of this and future pandemics

Barely 1 year after severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was first reported in China, the virus has infected approximately 120 million people, caused around 3 million deaths, and adversely affected the global economy. Despite stringent measures to flatten the epidemiologic curve of the pandemic, there have been spikes and waves of the infection in many countries, particularly in the American, European, and Asian continents. This review critically evaluated the global epidemiology of the novel coronavirus disease 2019 (COVID-19) to provide advice on other possible ways of managing the disease as various COVID-19 vaccines are being rolled out. To effectively control this and possible future epidemics/pandemics, there is a need to maintain a healthy balance between saving lives and livelihoods in the implementation of lockdowns. Unwarranted human exposures to animals, particularly pangolins, civet cats, bats, dromedary camels, and other wildlife known to be reservoirs and intermediate hosts of coronaviruses should be prevented. All the identified strains of SARS-CoV-2, including the highly infectious UK and South African variants, should be incorporated in COVID-19 vaccine production; to widen the protection spectrum. Some of the COVID-19 vaccines require primary inoculation, booster vaccination after 2-4 weeks and annual revaccination for adequate immunization against SARS-CoV-2. Survivors of COVID-19 may require only a single vaccine dozing and annual revaccination thereafter. Adoption of One Health approach and the development of globally coordinated active surveillance systems against emerging and reemerging zoonotic viruses are imperative.

Cardiovascular Injury Due to SARS-CoV-2

Purpose of Review

The world is currently facing the largest global health crisis since the early 1900s due to a novel coronavirus. While SARS-CoV-2 infection causes predictable symptoms in COVID-19 patients, including upper respiratory distress and fever, the heterogeneity of manifestations is surprising. This review focuses on direct and indirect causes of myocardial injury in COVID-19 patients and highlights current knowledge, treatment strategies, and outstanding questions in the field.

Recent Findings

Data are emerging that highlight the extent of cardiovascular involvement in COVID-19 patients, including evidence that SARS-CoV-2 causes myocarditis and increases cardiac risk. The incidence of cardiac injury is much greater in patients with severe disease presentation and those in intensive care.

Summary

During the past year, COVID-19 patient mortality rates have improved due to tailored pharmacological treatments and patient management strategies that address the unique presentation of symptoms, which will hopefully also reduce the incidence of cardiac injury.

Immunological imprint of COVID-19 on human peripheral blood leukocyte populations

Background

SARS‐CoV‐2 has triggered a pandemic that is now claiming many lives. Several studies have investigated cellular immune responses in COVID‐19‐infected patients during disease but little is known regarding a possible protracted impact of COVID‐19 on the adaptive and innate immune system in COVID‐19 convalescent patients.

Methods

We used multiparametric flow cytometry to analyze whole peripheral blood samples and determined SARS‐CoV‐2‐specific antibody levels against the S‐protein, its RBD‐subunit, and viral nucleocapsid in a cohort of COVID‐19 convalescent patients who had mild disease ~10 weeks after infection (n = 109) and healthy control subjects (n = 98). Furthermore, we correlated immunological changes with clinical and demographic parameters.

Results

Even ten weeks after disease COVID‐19 convalescent patients had fewer neutrophils, while their cytotoxic CD8⁺ T cells were activated, reflected as higher HLA‐DR and CD38 expression. Multiparametric regression analyses showed that in COVID‐19‐infected patients both CD3⁺CD4⁺ and CD3⁺CD8⁺ effector memory cells were higher, while CD25⁺Foxp3⁺ T regulatory cells were lower. In addition, both transitional B cell and plasmablast levels were significantly elevated in COVID‐19‐infected patients. Fever (duration, level) correlated with numbers of central memory CD4⁺ T cells and anti‐S and anti‐RBD, but not anti‐NC antibody levels. Moreover, a “young immunological age” as determined by numbers of CD3⁺CD45RA⁺CD62L⁺CD31⁺ recent thymic emigrants was associated with a loss of sense of taste and/or smell.

Conclusion

Acute SARS‐CoV‐2 infection leaves protracted beneficial (ie, activation of T cells) and potentially harmful (ie, reduction of neutrophils) imprints in the cellular immune system in addition to induction of specific antibody responses.

SARS-CoV-2 mediated neuroinflammation and the impact of COVID-19 in neurological disorders

SARS-CoV-2 is a novel coronavirus that severely affects the respiratory system, is the cause of the COVID-19 pandemic, and is projected to result in the deaths of 2 million people worldwide. Recent reports suggest that SARS-CoV-2 also affects the central nervous system along with other organs. COVID-19-associated complications are observed in older people with underlying neurological conditions like stroke, Alzheimer's disease, and Parkinson's disease. Hence, we discuss SARS-CoV-2 viral replication and its inflammation-mediated infection. This review also focuses on COVID-19 associated neurological complications in individuals with those complications as well as other groups of people. Finally, we also briefly discuss the current therapies available to treat patients, as well as ongoing available treatments and vaccines for effective cures with a special focus on the therapeutic potential of a small 5 amino acid peptide (PHSCN), ATN-161, that inhibits SARS-CoV-2 spike protein binding to both integrin α5β1 and α5β1/hACE2.

Heme Oxygenase-1 Deficiency and Oxidative Stress: A Review of 9 Independent Human Cases and Animal Models

Since Yachie et al. reported the first description of human heme oxygenase (HO)-1 deficiency more than 20 years ago, few additional human cases have been reported in the literature. A detailed analysis of the first human case of HO-1 deficiency revealed that HO-1 is involved in the protection of multiple tissues and organs from oxidative stress and excessive inflammatory reactions, through the release of multiple molecules with anti-oxidative stress and anti-inflammatory functions. HO-1 production is induced in vivo within selected cell types, including renal tubular epithelium, hepatic Kupffer cells, vascular endothelium, and monocytes/macrophages, suggesting that HO-1 plays critical roles in these cells. In vivo and in vitro studies have indicated that impaired HO-1 production results in progressive monocyte dysfunction, unregulated macrophage activation and endothelial cell dysfunction, leading to catastrophic systemic inflammatory response syndrome. Data from reported human cases of HO-1 deficiency and numerous studies using animal models suggest that HO-1 plays critical roles in various clinical settings involving excessive oxidative stress and inflammation. In this regard, therapy to induce HO-1 production by pharmacological intervention represents a promising novel strategy to control inflammatory diseases.

Immune system response during viral Infections: Immunomodulators, cytokine storm (CS) and Immunotherapeutics in COVID-19

Coronaviruses are non-segmented and single stranded positive-sense RNA (+ssRNA) viruses. To date, 06 human coronaviruses (HCoVs) are reported; α-CoVs (HCoVs-NL63 and HCoVs-229E) and β-CoVs (HCoVs-OC43, HCoVs-HKU1, SARS-CoV, MERS-CoV). While, novel coronavirus (SARS-CoV-2) is the most recent member. The genome sequence of SARS-CoV-2 is 82% similar to SARS-COV-1. The compelling evidences link the progression of viral infection of SARS-CoV-2 with excessive inflammation as a result of the exaggerated immune response and elevated production of "immunocytokines" resulting in cytokine storm (CS); followed by a series of events, like acute organ damage, acute respiratory distress syndrome (ARDS) as well as death. Hence attempts to reduce cytokine storm are now being considered as a new paradigm shift in the clinical management of SARS-CoV-2. Tocilizumab (IL-6 blocker), Baricitinib (JAKs and AAK1 inhibitor), TNFα inhibitors (Infliximab, Adalimumab, Certolizumab) are currently being evaluated for possible block of the CS. Hence, rationalizing anti-inflammatory therapeutics would be the most judicious approach for significant reduction in COVID-19 mortality. In order to elucidate optimized and rationaled use of different therapeutics in COVID-19, we collated latest available information from emerging scientific evidences, integrated previous attempts as well as clinical successes, and various adopted approaches to mitigate past outbreaks with of SARS-CoV and MERS CoV.

Pancytopenia and Profound Neutropenia as a Sequela of Severe SARS-CoV-2 Infection (COVID-19) With Concern for Bone Marrow Involvement

Pancytopenia and neutropenia due to coronavirus disease 2019 (COVID-19) are rare. Here we report a case of neutropenia as a sequela of COVID-19 with concern for bone marrow infiltration. The patient was successfully treated with granulocyte colony-stimulating factor.

An integrative look at SARS‑CoV‑2 (Review)

SARS‑CoV‑2 is a newly discovered member of the betacoronaviruses and the etiological agent of the disease COVID‑19. SARS‑CoV‑2 is responsible for the worldwide pandemic which has been taking place in 2020, and is causing a markedly higher number of infections and deaths compared to previous coronaviruses, such as SARS‑CoV or MERS‑CoV. Based on updated scientific literature, the present review compiles the most relevant knowledge of SARS‑CoV‑2, COVID‑19 and the clinical and typical responses that patients have exhibited against this virus, discussing current and future therapies, and proposing strategies with which to combat the disease and prevent a further global threat. The aggressiveness of SARS‑CoV‑2 arises from its capacity to infect, and spread easily and rapidly through its tight interaction with the human angiotensin‑converting enzyme 2 (ACE‑2) receptor. While not all patients respond in a similar manner and may even be asymptomatic, a wide range of manifestations associated with COVID‑19 have been described, particularly in vulnerable population groups, such as the elderly or individuals with other underlying conditions. The proper function of the immune system plays a key role in an individual's favorable response to SARS‑CoV‑2 infection. A hyperactivated response, on the contrary, could account for the more severe cases of COVID‑19, and this may finally lead to respiratory insufficiency and other complications, such as thrombotic or thromboembolic events. The development of novel therapies and vaccines designed to control and regulate a proper immune system response will be key to clinical management, prevention measures and effective population screening to attenuate the transmission of this novel RNA virus.

Pattern of circulating SARS-CoV-2-specific antibody-secreting and memory B-cell generation in patients with acute COVID-19

Objectives

To predict the spread of coronavirus disease (COVID‐19), information regarding the immunological memory for disease‐specific antigens is necessary. The possibility of reinfection, as well as the efficacy of vaccines for COVID‐19 that are currently under development, will largely depend on the quality and longevity of immunological memory in patients. To elucidate the process of humoral immunity development, we analysed the generation of plasmablasts and virus receptor‐binding domain (RBD)‐specific memory B (Bmem) cells in patients during the acute phase of COVID‐19.

Methods

The frequencies of RBD‐binding plasmablasts and RBD‐specific antibody‐secreting cells (ASCs) in the peripheral blood samples collected from patients with COVID‐19 were measured using flow cytometry and the ELISpot assay.

Results

The acute phase of COVID‐19 was characterised by the transient appearance of total as well as RBD‐binding plasmablasts. ELISpot analysis indicated that most patients exhibited a spontaneous secretion of RBD‐specific ASCs in the circulation with good correlation between the IgG and IgM subsets. IL‐21/CD40L stimulation of purified B cells induced the activation and proliferation of Bmem cells, which led to the generation of plasmablast phenotypic cells as well as RBD‐specific ASCs. No correlation was observed between the frequency of Bmem cell‐derived and spontaneous ASCs, suggesting that the two types of ASCs were weakly associated with each other.

Conclusion

Our findings reveal that SARS‐CoV‐2‐specific Bmem cells are generated during the acute phase of COVID‐19. These findings can serve as a basis for further studies on the longevity of SARS‐CoV‐2‐specific B‐cell memory.

Transient Anti-Phospholipid Antibodies in Two Patients With COVID-19

We report two cases of coronavirus disease 2019 (COVID-19) in patients who developed pulmonary embolism and transient anti-phospholipid antibodies. At the time of presentation with acute pulmonary embolism, both patients had leukocytosis and increased levels of anti-cardiolipin antibodies, which resolved at testing 12 weeks after initial presentation. Studying cases of pulmonary embolism and increased anti-phospholipid antibodies in the context of COVID-19 could be one of the factors for elucidating the possible connection between severe acute respiratory syndrome coronavirus 2 infection, anti-phospholipid antibodies, and thrombosis.

Calming the Storm: Natural Immunosuppressants as Adjuvants to Target the Cytokine Storm in COVID-19

The COVID-19 pandemic has caused a global health crisis, with no specific antiviral to treat the infection and the absence of a suitable vaccine to prevent it. While some individuals contracting the SARS-CoV-2 infection exhibit a well coordinated immune response and recover, others display a dysfunctional immune response leading to serious complications including ARDS, sepsis, MOF; associated with morbidity and mortality. Studies revealed that in patients with a dysfunctional immune response, there is a massive cytokine and chemokine release, referred to as the 'cytokine storm'. As a result, such patients exhibit higher levels of pro-inflammatory/modulatory cytokines and chemokines like TNFα, INFγ, IL-1β, IL-2, IL-4, IL-6, IL-7, IL-9, IL-10, IL-12, IL-13, IL-17, G-CSF, GM-CSF, MCSF, HGF and chemokines CXCL8, MCP1, IP10, MIP1α and MIP1β. Targeting this cytokine storm is a novel, promising treatment strategy to alleviate this excess influx of cytokines observed at the site of infection and their subsequent disastrous consequences. Natural immunosuppressant compounds, derived from plant sources like curcumin, luteolin, piperine, resveratrol are known to inhibit the production and release of pro-inflammatory cytokines and chemokines. This inhibitory effect is mediated by altering signal pathways like NF-κB, JAK/STAT, MAPK/ERK that are involved in the production and release of cytokines and chemokines. The use of these natural immunosuppressants as adjuvants to ameliorate the cytokine storm; in combination with antiviral agents and other treatment drugs currently in use presents a novel, synergistic approach for the treatment and effective cure of COVID-19. This review briefly describes the immunopathogenesis of the cytokine storm observed in SARS-CoV-2 infection and details some natural immunosuppressants that can be used as adjuvants in treating COVID-19 disease.

The Nucleocapsid protein triggers the main humoral immune response in COVID-19 patients

In order to control the COVID-19 pandemic caused by SARS-CoV-2 infection, serious progress has been made to identify infected patients and to detect patients with a positive immune response against the virus. Currently, attempts to generate a vaccine against the coronavirus are ongoing. To understand SARS-CoV-2 immunoreactivity, we compared the IgG antibody response against SARS-CoV-2 in infected versus control patients by dot blot using recombinant viral particle proteins: N (Nucleocapsid), M (Membrane) and S (Spike). In addition, we used different protein fragments of the N and S protein to map immune epitopes. Most of the COVID-19 patients presented a specific immune response against the full length and fragments of the N protein and, to lesser extent, against a fragment containing amino acids 300-685 of the S protein. In contrast, immunoreactivity against other S protein fragments or the M protein was low. This response is specific for COVID-19 patients as very few of the control patients displayed immunoreactivity, likely reflecting an immune response against other coronaviruses. Altogether, our results may help develop method(s) for measuring COVID-19 antibody response, selectivity of methods detecting such SARS-CoV-2 antibodies and vaccine development.

COVID-19: Characteristics and Therapeutics

Novel coronavirus (COVID-19 or 2019-nCoV or SARS-CoV-2), which suddenly emerged in December 2019 is still haunting the entire human race and has affected not only the healthcare system but also the global socioeconomic balances. COVID-19 was quickly designated as a global pandemic by the World Health Organization as there have been about 98.0 million confirmed cases and about 2.0 million confirmed deaths, as of January 2021. Although, our understanding of COVID-19 has significantly increased since its outbreak, and multiple treatment approaches and pharmacological interventions have been tested or are currently under development to mitigate its risk-factors. Recently, some vaccine candidates showed around 95% clinical efficacy, and now receiving emergency use approvals in different countries. US FDA recently approved BNT162 and mRNA-1273 vaccines developed by Pfizer/BioNTech and Moderna Inc. for emergency use and vaccination in the USA. In this review, we present a succinct overview of the SARS-CoV-2 virus structure, molecular mechanisms of infection, COVID-19 epidemiology, diagnosis, and clinical manifestations. We also systematize different treatment strategies and clinical trials initiated after the pandemic outbreak, based on viral infection and replication mechanisms. Additionally, we reviewed the novel pharmacological intervention approaches and vaccine development strategies against COVID-19. We speculate that the current pandemic emergency will trigger detailed studies of coronaviruses, their mechanism of infection, development of systematic drug repurposing approaches, and novel drug discoveries for current and future pandemic outbreaks.

Immunoinformatics prediction of overlapping CD8+ T-cell, IFN-γ and IL-4 inducer CD4+ T-cell and linear B-cell epitopes based vaccines against COVID-19 (SARS-CoV-2)

At the beginning of the year 2020, the world was struck with a global pandemic virus referred to as SARS-CoV-2 (COVID-19) which has left hundreds of thousands of people dead. To control this virus, vaccine design becomes imperative. In this study, potential epitopes-based vaccine candidates were explored. Six hundred (600) genomes of SARS-CoV-2 were retrieved from the viPR database to generate CD8⁺ T-cell, CD4+ T-cell and linear B-cell epitopes which were screened for antigenicity, immunogenicity and non-allergenicity. The results of this study provide 19 promising candidate CD8⁺ T-cell epitopes that strongly overlap with 8 promising B-cells epitopes. Another 19 CD4⁺ T-cell epitopes were also identified that can induce IFN-γ and IL-4 cytokines. The most conserved MHC-I and MHC-II for both CD8⁺ and CD4⁺ T-cell epitopes are HLA-A*02:06 and HLA-DRB1*01:01 respectively. These epitopes also bound to Toll-like receptor 3 (TLR3). The population coverage of the conserved Major Histocompatibility Complex Human Leukocyte Antigen (HLA) for both CD8⁺ T-cell and CD4⁺ T-cell ranged from 65.6% to 100%. The detailed analysis of the potential epitope-based vaccine and their mapping to the complete COVID-19 genome reveals that they are predominantly found in the location of the surface (S) and membrane (M) glycoproteins suggesting the potential involvement of these structural proteins in the immunogenic response and antigenicity of the virus. Since the majority of the potential epitopes are located on M protein, the design of multi-epitope vaccine with the structural protein is highly promising though the whole M protein could also serve as a viable epitope for the development of an attenuated vaccine. Our findings provide a baseline for the experimental design of a suitable vaccine against SARS-CoV-2.

HIV/SARS-CoV-2 co-infection: T cell profile, cytokine dynamics and role of exhausted lymphocytes

OBJECTIVES

The aim was to investigate if there is synergy in HIV infection and COVID-19 in their influence on human immunity, if there is an exacerbation of HIV patients' immune status caused by SARS-CoV-2; and if HIV infection without antiretroviral therapy (ART) leads to a more serious COVID-19 course than HIV infection with ART.

DESIGN

Anonymised blood samples and clinical data were collected in 47 hospitals, clinics and medical centres in six Russian cities/regions in the period from 20 March to 15 June 2020. Three hundred and seventy-six HIV/COVID-19 patients were studied (171 without ART and 205 with ART). The control group consisted of 382 SARS-CoV-2-positive patients without HIV infection. Lymphocyte and cytokine amounts were measured by flow cytometry and ELISA. This work is a retrospective study.

RESULTS

COVID-19 led to rapid augmentation of the process of T-cell exhaustion initially caused by HIV, and this T cell degradation was most pronounced in patients without ART. A rise in IL-10 and TGFβ serum concentrations was observed. Diminishing CD4+/CD8+ cell and Th1/Th2 cell ratios characteristic for HIV progression were accompanied by a surge in exhausted T cell count with simultaneous exacerbation of COVID-19-related respiratory distress.

CONCLUSIONS

HIV infection without ART may be a very serious comorbidity of COVID-19, whereas immunity of HIV/COVID-19 patients with proper ART is not generally affected by SARS-CoV-2. HIV-1 and SARS-CoV-2 are likely to exhibit a synergic effect, and exhausted T lymphocyte dynamics may be its effective marker.

T-cell responses and therapies against SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2, a novel coronavirus strain. Some studies suggest that COVID-19 could be an immune-related disease, and failure of effective immune responses in initial stages of viral infection could contribute to systemic inflammation and tissue damage, leading to worse disease outcomes. T cells can act as a double-edge sword with both pro- and anti-roles in the progression of COVID-19. Thus, better understanding of their roles in immune responses to SARS-CoV-2 infection is crucial. T cells primarily react to the spike protein on the coronavirus to initiate antiviral immunity; however, T-cell responses can be suboptimal, impaired or excessive in severe COVID-19 patients. This review focuses on the multifaceted roles of T cells in COVID-19 pathogenesis and rationalizes their significance in eliciting appropriate antiviral immune responses in COVID-19 patients and unexposed individuals. In addition, we summarize the potential therapeutic approaches related to T cells to treat COVID-19 patients. These include adoptive T-cell therapies, vaccines activating T-cell responses, recombinant cytokines, Th1 activators and Th17 blockers, and potential utilization of immune checkpoint inhibitors alone or in combination with anti-inflammatory drugs to improve antiviral T-cell responses against SARS-CoV-2.

Immune response and possible therapeutics in COVID-19

COVID-19 has emerged as a pandemic affecting about 213 countries in all the continents of the globe, resulting in more than 37.8 million individuals getting infected and over 1.08 million deaths worldwide, jeopardizing global human health and the economy. This presents an urgent need to develop therapies that target the SARS-CoV2 virus specifically. This review aims at presenting the available information on the coronavirus disease 2019 along with various drugs that are having widespread use until a vaccine candidate is available to aid in the development of therapeutic strategies against COVID-19.

Transcriptomic similarities and differences in host response between SARS-CoV-2 and other viral infections

The pandemic 2019 novel coronavirus disease (COVID-19) shares certain clinical characteristics with other acute viral infections. We studied the whole-blood transcriptomic host response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using RNAseq from 24 healthy controls and 62 prospectively enrolled patients with COVID-19. We then compared these data to non-COVID-19 viral infections, curated from 23 independent studies profiling 1,855 blood samples covering six viruses (influenza, respiratory syncytial virus (RSV), human rhinovirus (HRV), severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1), Ebola, dengue). We show gene expression changes in COVID-19 versus non-COVID-19 viral infections are highly correlated (r = 0.74, p < 0.001). However, we also found 416 genes specific to COVID-19. Inspection of top genes revealed dynamic immune evasion and counter host responses specific to COVID-19. Statistical deconvolution of cell proportions maps many cell type proportions concordantly shifting. Discordantly increased in COVID-19 were CD56^bright natural killer cells and M2 macrophages. The concordant and discordant responses mapped out here provide a window to explore the pathophysiology of the host response to SARS-CoV-2.

Reinfection risk of novel coronavirus (COVID-19): A systematic ‎review of current evidence

BACKGROUND

There is recently a concern regarding the reinfection and reactivation of previously reCoVered coronavirus disease 2019 (CoVID-19) patients.

AIM

To summarize the recent findings and reports of CoVID-19 reinfection in patients previously reCoVered from the disease.

METHODS

This study was a systematic review of current evidence conducted in August 2020. The authors studied the probable reinfection risk of novel coronavirus (CoVID-19). We performed a systematic search using the keywords in online databases. The investigation adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist to ensure the reliability and validity of this study and results.

RESULTS

We reviewed 31 studies. Eight studies described reCoVered patients with reinfection. Only one study reported reinfected patients who died. In 26 studies, there was no information about the status of the patients. Several studies indicated that reinfection is not probable and that post-infection immunity is at least temporary and short.

CONCLUSION

Based on our review, we concluded that a positive polymerase chain reaction retest could be due to several reasons and should not always be considered as reinfection or reactivation of the disease. Most relevant studies in positive retest patients have shown relative and probably temporary immunity after the reCoVery of the disease.

Elevated SARS-CoV-2 Antibodies Distinguish Severe Disease in Early COVID-19 Infection

Background

SARS-CoV-2 has caused over 36,000,000 cases and 1,000,000 deaths globally. Comprehensive assessment of the multifaceted anti-viral antibody response is critical for diagnosis, differentiation of severe disease, and characterization of long-term immunity. Initial observations suggest that severe disease is associated with higher antibody levels and greater B cell/plasmablast responses. A multi-antigen immunoassay to define the complex serological landscape and clinical associations is essential.

Methods

We developed a multiplex immunoassay and evaluated serum/plasma from adults with RT-PCR-confirmed SARS-CoV-2 infections during acute illness (N=52) and convalescence (N=69); and pre-pandemic (N=106) and post-pandemic (N=137) healthy adults. We measured IgA, IgG, and/or IgM against SARS-CoV-2 Nucleocapsid (N), Spike domain 1 (S1), receptor binding domain (S1-RBD) and S1-N-terminal domain (S1-NTD).

Results

To diagnose infection, the combined [IgA+IgG+IgM] or IgG for N, S1, and S1-RBD yielded AUC values -0.90 by ROC curves. From days 6-30 post-symptom onset, the levels of antigen-specific IgG, IgA or [IgA+IgG+IgM] were higher in patients with severe/critical compared to mild/moderate infections. Consistent with excessive concentrations of antibodies, a strong prozone effect was observed in sera from severe/critical patients. Notably, mild/moderate patients displayed a slower rise and lower peak in anti-N and anti-S1 IgG levels compared to severe/critical patients, but anti-RBD IgG and neutralization responses reached similar levels at 2-4 months.

Conclusion

This SARS-CoV-2 multiplex immunoassay measures the magnitude, complexity and kinetics of the antibody response against multiple viral antigens. The IgG and combined-isotype SARS-CoV-2 multiplex assay is highly diagnostic of acute and convalescent disease and may prognosticate severity early in illness.

One Sentence Summary

In contrast to patients with moderate infections, those with severe COVID-19 develop prominent, early antibody responses to S1 and N proteins.

Repositioning Vitamin C as a Promising Option to Alleviate Complications associated with COVID-19

Vitamin C, also known as L-ascorbic acid, is an essential vitamin with pleiotropic functions, ranging from antioxidant to anti-microbial functions. Evidence suggests that vitamin C acts against inflammation, oxidative stress, autophagy chaos, and immune dysfunction. The ability to activate and enhance the immune system makes this versatile vitamin a prospective therapeutic agent amid the current situation of coronavirus disease 2019 (COVID-19). Being highly effective against the influenza virus, causing the common cold, vitamin C may also function against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its associated complications. Severe infections need higher doses of the vitamin to compensate for the augmented inflammatory response and metabolic demand that commonly occur during COVID-19. Compelling evidence also suggests that a high dose of vitamin C (1.5 g/kg body weight) in inflammatory conditions can result in effective clinical outcomes and thus can be employed to combat COVID-19. However, further studies are crucial to delineate the mechanism underlying the action of vitamin C against COVID-19. The current review aims to reposition vitamin C as an alternative approach for alleviating COVID-19-associated complications.

Pre-Hospital Management of Critically Ill Patients with SARS-CoV-2 Infection: A Retrospective Multicenter Study

INTRODUCTION

The COVID-19 outbreak had a major impact on healthcare systems worldwide. Our study aims to describe the characteristics and therapeutic emergency mobile service (EMS) management of patients with vital distress due to COVID-19, their in-hospital care pathway and their in-hospital outcome.

METHODS

This retrospective and multicentric study was conducted in the six main centers of the French Greater East region, an area heavily impacted by the pandemic. All patients requiring EMS dispatch and who were admitted straight to the intensive care unit (ICU) were included. Clinical data from their pre-hospital and hospital management were retrieved.

RESULTS

We included a total of 103 patients (78.6% male, median age 68). In the initial stage, patients were in a critical condition (median oxygen saturation was 72% (60-80%)). In the field, 77.7% (CI 95%: 71.8-88.3%) were intubated. Almost half of our population (45.6%, CI 95%: 37.1-56.9%) had clinical Phenotype 1 (silent hypoxemia), while the remaining half presented Phenotype 2 (acute respiratory failure). In the ICU, a great number had ARDS (77.7%, CI 95% 71.8-88.3% with a PaO2/FiO2 < 200). In-hospital mortality was 33% (CI 95%: 24.6-43.3%). The two phenotypes showed clinical and radiological differences (respiratory rate, OR = 0.98, p = 0.02; CT scan lesion extension >50%, OR = 0.76, p < 0.03). However, no difference was found in terms of overall in-hospital mortality (OR = 1.07, p = 0.74).

CONCLUSION

The clinical phenotypes appear to be very distinguishable in the pre-hospital field, yet no difference was found in terms of mortality. This leads us to recommend an identical management in the initial phase, despite the two distinct presentations.

Pharmacogenomics of genetic polymorphism within the genes responsible for SARS-CoV-2 susceptibility and the drug-metabolising genes used in treatment

The ongoing outbreak of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) represents a significant challenge to international health. Pharmacogenomics aims to identify the different genetic variations that exist between individuals and populations in order to determine appropriate treatment protocols to enhance the efficacy of drugs and reduce their side‐effects. This literature review provides an overview of recent studies of genetic polymorphisms in genes that mediate the SARS‐CoV‐2 infection mechanism (ACE1, ACE2, TMPRSS2 and CD26). In addition, genetic variations in the drug‐metabolising enzyme genes of several selected drugs used in the treatment of COVID‐19 are summarised. This may help construct an effective health protocol based on genetic biomarkers to optimise response to treatment. Potentially, pharmacogenomics could contribute to the development of effective high‐throughput assays to improve patient evaluation, but their use will also create ethical, medical, regulatory, and legal issues, which should now be considered in the era of personalised medicine.

Dangerous Pathogens as a Potential Problem for Public Health

Pathogens are various organisms, such as viruses, bacteria, fungi, and protozoa, which can cause severe illnesses to their hosts. Throughout history, pathogens have accompanied human populations and caused various epidemics. One of the most significant outbreaks was the Black Death, which occurred in the 14th century and caused the death of one-third of Europe's population. Pathogens have also been studied for their use as biological warfare agents by the former Soviet Union, Japan, and the USA. Among bacteria and viruses, there are high priority agents that have a significant impact on public health. Bacillus anthracis, Francisella tularensis, Yersinia pestis, Variola virus, Filoviruses (Ebola, Marburg), Arenoviruses (Lassa), and influenza viruses are included in this group of agents. Outbreaks and infections caused by them might result in social disruption and panic, which is why special operations are needed for public health preparedness. Antibiotic-resistant bacteria that significantly impede treatment and recovery of patients are also valid threats. Furthermore, recent events related to the massive spread of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are an example of how virus-induced diseases cannot be ignored. The impact of outbreaks, such as SARS-CoV-2, have had far-reaching consequences beyond public health. The economic losses due to lockdowns are difficult to estimate, but it would take years to restore countries to pre-outbreak status. For countries affected by the 2019 coronavirus disease (COVID-19), their health systems have been overwhelmed, resulting in an increase in the mortality rate caused by diseases or injuries. Furthermore, outbreaks, such as SARS-CoV-2, will induce serious, wide-ranging (and possibly long-lasting) psychological problems among, not only health workers, but ordinary citizens (this is due to isolation, quarantine, etc.). The aim of this paper is to present the most dangerous pathogens, as well as general characterizations, mechanisms of action, and treatments.

Abnormal antibodies to self-carbohydrates in SARS-CoV-2 infected patients

SARS-CoV-2 is a deadly virus that is causing the global pandemic coronavirus disease 2019 (COVID-19). Our immune system plays a critical role in preventing, clearing, and treating the virus, but aberrant immune responses can contribute to deleterious symptoms and mortality. Many aspects of immune responses to SARS-CoV-2 are being investigated, but little is known about immune responses to carbohydrates. Since the surface of the virus is heavily glycosylated, pre-existing antibodies to glycans could potentially recognize the virus and influence disease progression. Furthermore, antibody responses to carbohydrates could be induced, affecting disease severity and clinical outcome. In this study, we used a carbohydrate antigen microarray with over 800 individual components to profile serum anti-glycan antibodies in COVID-19 patients and healthy control subjects. In COVID-19 patients, we observed abnormally high IgG and IgM antibodies to numerous self-glycans, including gangliosides, N -linked glycans, LacNAc-containing glycans, blood group H, and sialyl Lewis X. Some of these anti-glycan antibodies are known to play roles in autoimmune diseases and neurological disorders, which may help explain some of the unusual and prolonged symptoms observed in COVID-19 patients. The detection of antibodies to self-glycans has important implications for using convalescent serum to treat patients, developing safe and effective SARS-CoV-2 vaccines, and understanding the risks of infection. In addition, this study provides new insight into the immune responses to SARS-CoV-2 and illustrates the importance of including host and viral carbohydrate antigens when studying immune responses to viruses.