SARS-CoV-2 viral load and antibody responses: the case for convalescent plasma therapy

Generating the Evidence Base for Convalescent Plasma Use for a New Infectious Disease

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) swept across the world in the waning months of 2019 and emerged as the cause of the coronavirus disease 19 (COVID-19) pandemic in early 2020. The use of convalescent plasma (CP) for prior respiratory pandemics provided a strong biological rationale for the rapid deployment of COVID-19 convalescent plasma (CCP) in early 2020 when no validated treatments or prior immunity existed. CCP is an antiviral agent, with its activity against SARS-CoV-2 stemming from specific antibodies elicited by the virus. Early efforts to investigate the efficacy of CCP in randomized clinical trials (RCTs) that targeted hospitalized patients with COVID-19 did not demonstrate the overall efficacy of CCP despite signals of benefit in certain subgroups, such as those treated earlier in disease. In contrast, studies adhering to the principles of antibody therapy in their study design, choice of patient population, and product qualification, i.e., those that administered high levels of specific antibody during the viral phase of disease in immunocompromised or very early in immunocompetent individuals, demonstrated benefits. In this chapter, we leverage the knowledge gained from clinical studies of CCP for COVID-19 to propose a framework for future studies of CP for a new infectious disease. This framework includes obtaining high-quality CP and designing clinical studies that adhere to the principles of antibody therapy to generate a robust evidence base for using CP.

Single MVA-SARS-2-ST/N Vaccination Rapidly Protects K18-hACE2 Mice against a Lethal SARS-CoV-2 Challenge Infection

The sudden emergence of SARS-CoV-2 demonstrates the need for new vaccines that rapidly protect in the case of an emergency. In this study, we developed a recombinant MVA vaccine co-expressing SARS-CoV-2 prefusion-stabilized spike protein (ST) and SARS-CoV-2 nucleoprotein (N, MVA-SARS-2-ST/N) as an approach to further improve vaccine-induced immunogenicity and efficacy. Single MVA-SARS-2-ST/N vaccination in K18-hACE2 mice induced robust protection against lethal respiratory SARS-CoV-2 challenge infection 28 days later. The protective outcome of MVA-SARS-2-ST/N vaccination correlated with the activation of SARS-CoV-2-neutralizing antibodies (nABs) and substantial amounts of SARS-CoV-2-specific T cells especially in the lung of MVA-SARS-2-ST/N-vaccinated mice. Emergency vaccination with MVA-SARS-2-ST/N just 2 days before lethal SARS-CoV-2 challenge infection resulted in a delayed onset of clinical disease outcome in these mice and increased titers of nAB or SARS-CoV-2-specific T cells in the spleen and lung. These data highlight the potential of a multivalent COVID-19 vaccine co-expressing S- and N-protein, which further contributes to the development of rapidly protective vaccination strategies against emerging pathogens.

Exercise and Experiments of Nature

In this article, we highlight the contributions of passive experiments that address important exercise-related questions in integrative physiology and medicine. Passive experiments differ from active experiments in that passive experiments involve limited or no active intervention to generate observations and test hypotheses. Experiments of nature and natural experiments are two types of passive experiments. Experiments of nature include research participants with rare genetic or acquired conditions that facilitate exploration of specific physiological mechanisms. In this way, experiments of nature are parallel to classical "knockout" animal models among human research participants. Natural experiments are gleaned from data sets that allow population-based questions to be addressed. An advantage of both types of passive experiments is that more extreme and/or prolonged exposures to physiological and behavioral stimuli are possible in humans. In this article, we discuss a number of key passive experiments that have generated foundational medical knowledge or mechanistic physiological insights related to exercise. Both natural experiments and experiments of nature will be essential to generate and test hypotheses about the limits of human adaptability to stressors like exercise. © 2023 American Physiological Society. Compr Physiol 13:4879-4907, 2023.

Potential treatments of COVID-19: Drug repurposing and therapeutic interventions

The coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The infection is caused when Spike-protein (S-protein) present on the surface of SARS-CoV-2 interacts with human cell surface receptor, Angiotensin-converting enzyme 2 (ACE2). This binding facilitates SARS-CoV-2 genome entry into the human cells, which in turn causes infection. Since the beginning of the pandemic, many different therapies have been developed to combat COVID-19, including treatment and prevention. This review is focused on the currently adapted and certain other potential therapies for COVID-19 treatment, which include drug repurposing, vaccines and drug-free therapies. The efficacy of various treatment options is constantly being tested through clinical trials and in vivo studies before they are made medically available to the public.

Therapeutic equine hyperimmune antibodies with high and broad-spectrum neutralizing activity protect rodents against SARS-CoV-2 infection

The emergence of SARS-CoV-2 variants stresses the continued need for broad-spectrum therapeutic antibodies. Several therapeutic monoclonal antibodies or cocktails have been introduced for clinical use. However, unremitting emerging SARS-CoV-2 variants showed reduced neutralizing efficacy by vaccine induced polyclonal antibodies or therapeutic monoclonal antibodies. In our study, polyclonal antibodies and F(ab')₂ fragments with strong affinity produced after equine immunization with RBD proteins produced strong affinity. Notably, specific equine IgG and F(ab')₂ have broad and high neutralizing activity against parental virus, all SARS-CoV-2 variants of concern (VOCs), including B.1.1,7, B.1.351, B.1.617.2, P.1, B.1.1.529 and BA.2, and all variants of interest (VOIs) including B.1.429, P.2, B.1.525, P.3, B.1.526, B.1.617.1, C.37 and B.1.621. Although some variants weaken the neutralizing ability of equine IgG and F(ab')₂ fragments, they still exhibited superior neutralization ability against mutants compared to some reported monoclonal antibodies. Furthermore, we tested the pre-exposure and post-exposure protective efficacy of the equine immunoglobulin IgG and F(ab')₂ fragments in lethal mouse and susceptible golden hamster models. Equine immunoglobulin IgG and F(ab')₂ fragments effectively neutralized SARS-CoV-2 in vitro, fully protected BALB/c mice from the lethal challenge, and reduced golden hamster's lung pathological change. Therefore, equine pAbs are an adequate, broad coverage, affordable and scalable potential clinical immunotherapy for COVID-19, particularly for SARS-CoV-2 VOCs or VOIs.

A Four-Channel Surface Plasmon Resonance Sensor Functionalized Online for Simultaneous Detections of Anti-SARS-CoV-2 Antibody, Free Viral Particles, and Neutralized Viral Particles

Current tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detect either the constituent nucleic acids/proteins of the viral particles or antibodies specific to the virus, but cannot provide information about viral neutralization by an antibody and the efficacy of an antibody. Such information is important about individuals' vulnerability to severe symptoms or their likelihood of showing no symptoms. We immobilized online SARS-CoV-2 spike (S1) protein and angiotensin-converting enzyme 2 (ACE2) into separate surface plasmon resonance (SPR) channels of a tris-nitrilotriacetic acid (tris-NTA) chip to simultaneously detect the anti-S1 antibody and viral particles in serum samples. In addition, with a high-molecular-weight-cutoff filter, we separated the neutralized viral particles from the free antibody molecules and used a sensing channel immobilized with Protein G to determine antibody-neutralized viral particles. The optimal density of probe molecules in each fluidic channel can be precisely controlled through the closure and opening of the specific ports. By utilizing the high surface density of ACE2, multiple assays can be carried out without regenerations. These three species can be determined with a short analysis time (<12 min per assay) and excellent sensor-to-sensor/cycle-to-cycle reproducibility (RSD < 5%). When coupled with an autosampler, continuous assays can be performed in an unattended manner at a single chip for up to 6 days. Such a sensor capable of assaying serum samples containing the three species at different levels provides additional insights into the disease status and immunity of persons being tested, which should be helpful for containing the SARS-CoV-2 spread during the era of incessant viral mutations.

Isolation of SARS-CoV-2-blocking recombinant antibody fragments and characterisation of their binding to variant spike proteins

COVID-19 is a severe acute respiratory disease caused by SARS-CoV-2. From its initial appearance in Wuhan, China in 2019, it developed rapidly into a global pandemic. In addition to vaccines, therapeutic antibodies play an important role in immediately treating susceptible individuals to lessen severity of the disease. In this study, phage display technology was utilised to isolate human scFv antibody fragments that bind the receptor-binding domain (RBD) of SARS-CoV-2 Wuhan-Hu-1 spike protein. Of eight RBD-binding scFvs isolated, two inhibited interaction of RBD with ACE2 protein on VeroE6 cells. Both scFvs also exhibited binding to SARS-CoV-2 Delta variant spike protein but not to Omicron variant spike protein in a Raman spectroscopy immunotest. The study demonstrates the potential of recombinant antibody approaches to rapidly isolate antibody moieties with virus neutralisation potential.

Memory B cells and serum immunoglobulins are associated with disease severity and mortality in patients with COVID-19

PURPOSE OF THE STUDY

The aim of this study was to investigate the relationship of B cell-mediated immunity with disease severity and mortality in patients with COVID-19.

STUDY DESIGN

In this retrospective cohort and single-centre study, 208 patients with laboratory-confirmed COVID-19 were recruited. A COVID-19 severity score, ranging from 0 to 10, was used to evaluate associations between various factors. Serum immunoglobulin levels and the number of cells in B lymphocyte subsets were measured and their association with disease severity and mortality in patients with COVID-19 examined.

RESULTS

The median age of the patients was 50 (35-63) years and 88 (42%) were female. The number of deceased patients was 17. The median COVID-19 severity score was 8 (6-8) in deceased patients and 1 (0-2) in survivors. Deceased patients had significantly lower levels of total B lymphocytes, naive B cells, switched memory B cells, and serum IgA, IgG, IgG1 and IgG2 than recovered patients (all p<0.05). In addition, a significant negative correlation was found between the number of these parameters and COVID-19 severity scores. Decrease in the number of total B cells and switched memory B cells as well as lower serum IgA, IgG and IgG1 levels were independent risk factors for mortality in patients with COVID-19.

CONCLUSION

In the present study, the prognosis of patients with COVID-19 was shown to be associated with the B cell subset and serum immunoglobulin levels.

Dysregulation of immunity in COVID-19 and SLE

The immune response plays a crucial role in preventing diseases, such as infections. There are two types of immune responses, specific and innate immunity, each of which consists of two components: cellular immunity and humoral immunity. Dysfunction in any immune system component increases the risk of developing certain diseases. Systemic lupus erythematosus (SLE), an autoimmune disease in the human body, develops an immune response against its own components. In these patients, due to underlying immune system disorders and receipt of immunosuppressive drugs, the susceptibility to infections is higher than in the general population and is the single largest cause of mortality in this group. COVID-19 infection, which first appeared in late 2019, has caused several concerns in patients with SLE. However, there is no strong proof of additional risk of developing COVID-19 in patients with SLE, and in some cases, studies have shown less severity of the disease in these individuals. This review paper discusses the immune disorders in SLE and COVID-19.

Challenges in the Detection of SARS-CoV-2: Evolution of the Lateral Flow Immunoassay as a Valuable Tool for Viral Diagnosis

SARS-CoV-2 is an emerging infectious disease of zoonotic origin that caused the coronavirus disease in late 2019 and triggered a pandemic that has severely affected human health and caused millions of deaths. Early and massive diagnosis of SARS-CoV-2 infected patients is the key to preventing the spread of the virus and controlling the outbreak. Lateral flow immunoassays (LFIA) are the simplest biosensors. These devices are clinical diagnostic tools that can detect various analytes, including viruses and antibodies, with high sensitivity and specificity. This review summarizes the advantages, limitations, and evolution of LFIA during the SARS-CoV-2 pandemic and the challenges of improving these diagnostic devices.

Early COVID-19 respiratory risk stratification using machine learning

Background

COVID-19 has strained healthcare systems globally. In this and future pandemics, providers with limited critical care experience must distinguish between moderately ill patients and those who will require aggressive care, particularly endotracheal intubation. We sought to develop a machine learning-informed Early COVID-19 Respiratory Risk Stratification (ECoRRS) score to assist in triage, by providing a prediction of intubation within the next 48 hours based on objective clinical parameters.

Methods

Electronic health record data from 3447 COVID-19 hospitalizations, 20.7% including intubation, were extracted. 80% of these records were used as the derivation cohort. The validation cohort consisted of 20% of the total 3447 records. Multiple randomizations of the training and testing split were used to calculate confidence intervals. Data were binned into 4-hour blocks and labeled as cases of intubation or no intubation within the specified time frame. A LASSO (least absolute shrinkage and selection operator) regression model was tuned for sensitivity and sparsity.

Results

Six highly predictive parameters were identified, the most significant being fraction of inspired oxygen. The model achieved an area under the receiver operating characteristic curve of 0.789 (95% CI 0.785 to 0.812). At 90% sensitivity, the negative predictive value was 0.997.

Discussion

The ECoRRS score enables non-specialists to identify patients with COVID-19 at risk of intubation within 48 hours with minimal undertriage and enables health systems to forecast new COVID-19 ventilator needs up to 48 hours in advance.

Level of evidence

IV.

Autoimmune and immunoserological markers of COVID-19 pneumonia: Can they help in the assessment of disease severity

Background

Immune dysregulation and associated inefficient anti-viral immunity during Coronavirus Disease 2019 (COVID-19) can cause tissue and organ damage which shares many similarities with pathogenetic processes in systemic autoimmune diseases. In this study, we investigate wide range autoimmune and immunoserological markers in hospitalized patients with COVID-19.

Methods

Study included 51 patients with confirmed Severe Acute Respiratory Syndrome Coronavirus 2 infection and hospitalized due to COVID-19 pneumonia. Wide spectrum autoantibodies associated with different autoimmune inflammatory rheumatic diseases were analyzed and correlated with clinical and laboratory features and pneumonia severity.

Results

Antinuclear antibodies (ANA) positivity was found in 19.6%, anti-cardiolipin IgG antibodies (aCL IgG) in 15.7%, and anti-cardiolipin IgM antibodies (aCL IgM) in 7.8% of patients. Positive atypical x anti-neutrophil cytoplasmic antibodies (xANCA) were detected in 10.0% (all negative for Proteinase 3 and Myeloperoxidase) and rheumatoid factor was found in 8.2% of patients. None of tested autoantibodies were associated with disease or pneumonia severity, except for aCL IgG being significantly associated with higher pneumonia severity index (p = 0.036). Patients with reduced total serum IgG were more likely to require non-invasive mechanical ventilation (NIMV) (p < 0.0001). Serum concentrations of IgG (p = 0.003) and IgA (p = 0.032) were significantly lower in this group of patients. Higher total serum IgA (p = 0.009) was associated with mortality, with no difference in serum IgG (p = 0.115) or IgM (p = 0.175). Lethal outcome was associated with lower complement C4 (p = 0.013), while there was no difference in complement C3 concentration (p = 0.135).

Conclusion

Increased autoimmune responses are present in moderate and severe COVID-19. Severe pneumonia is associated with the presence of aCL IgG, suggesting their role in disease pathogenesis. Evaluation of serum immunoglobulins and complement concentration could help assess the risk of non-invasive mechanical ventilation NIMV and poor outcome.

Therapeutic monoclonal antibodies for COVID-19 management: an update

BACKGROUND

The first case of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral disease in the world was announced on 31^st December 2019 in Wuhan, China. Since then, this virus has affected more than 440 million people, and today the world is facing different mutant strains of the virus, leading to increased morbidity rates, fatality rates, and surfacing re-infections. Various therapies, such as prophylactic treatments, repurposed drug treatments, convalescent plasma, and polyclonal antibody therapy have been developed to help combat the coronavirus disease 2019 (COVID-19).

AREA COVERED

This review article provides insights into the basic aspects of monoclonal antibodies (mAbs) for the therapy of COVID-19, as well as its advancement in terms of clinical trial and current approval status.

EXPERT OPINION

Monoclonal antibodies represents the most effective and viable therapy and/or prophylaxis option against COVID-19, and have shown a reduction of the viral load, as well as lowering hospitalizations and death rates. In different countries, various mAbs are undergoing different phases of clinical trials, with a few of them having entered phases III and IV. Due to the soaring number of cases worldwide, the FDA has given emergency approval for the mAb combinations bamlanivimab with etesevimab and casirivimab with imdevimab.

Advances in Pathogenesis, Progression, Potential Targets and Targeted Therapeutic Strategies in SARS-CoV-2-Induced COVID-19

As the new year of 2020 approaches, an acute respiratory disease quietly caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as coronavirus disease 2019 (COVID-19) was reported in Wuhan, China. Subsequently, COVID-19 broke out on a global scale and formed a global public health emergency. To date, the destruction that has lasted for more than two years has not stopped and has caused the virus to continuously evolve new mutant strains. SARS-CoV-2 infection has been shown to cause multiple complications and lead to severe disability and death, which has dealt a heavy blow to global development, not only in the medical field but also in social security, economic development, global cooperation and communication. To date, studies on the epidemiology, pathogenic mechanism and pathological characteristics of SARS-CoV-2-induced COVID-19, as well as target confirmation, drug screening, and clinical intervention have achieved remarkable effects. With the continuous efforts of the WHO, governments of various countries, and scientific research and medical personnel, the public's awareness of COVID-19 is gradually deepening, a variety of prevention methods and detection methods have been implemented, and multiple vaccines and drugs have been developed and urgently marketed. However, these do not appear to have completely stopped the pandemic and ravages of this virus. Meanwhile, research on SARS-CoV-2-induced COVID-19 has also seen some twists and controversies, such as potential drugs and the role of vaccines. In view of the fact that research on SARS-CoV-2 and COVID-19 has been extensive and in depth, this review will systematically update the current understanding of the epidemiology, transmission mechanism, pathological features, potential targets, promising drugs and ongoing clinical trials, which will provide important references and new directions for SARS-CoV-2 and COVID-19 research.

Equine immunoglobulin fragment F(ab')2 displays high neutralizing capability against multiple SARS-CoV-2 variants

Neutralizing antibody-based passive immunotherapy could be an important therapeutic option against COVID-19. Herein, we demonstrate that equines hyper-immunized with chemically inactivated SARS-CoV-2 elicited high antibody titers with a strong virus-neutralizing potential, and F(ab')₂ fragments purified from them displayed strong neutralization potential against five different SARS-CoV-2 variants. F(ab')₂ fragments purified from the plasma of hyperimmunized horses showed high antigen-specific affinity. Experiments in rabbits suggested that the F(ab')₂ displays a linear pharmacokinetics with approximate plasma half-life of 47 h. In vitro microneutralization assays using the purified F(ab')₂ displayed high neutralization titers against five different variants of SARS-CoV-2 including the Delta variant, demonstrating its potential efficacy against the emerging viral variants. In conclusion, this study demonstrates that F(ab')₂ generated against SARS-CoV-2 in equines have high neutralization titers and have broad target-range against the evolving variants, making passive immunotherapy a potential regimen against the existing and evolving SARS-CoV-2 variants in combating COVID-19.

Use of Early Donated COVID-19 Convalescent Plasma Is Optimal to Preserve the Integrity of Lymphatic Endothelial Cells

Convalescent plasma therapy (CPT) has gained significant attention since the onset of the coronavirus disease 2019 (COVID-19) pandemic. However, clinical trials designed to study the efficacy of CPT based on antibody concentrations were inconclusive. Lymphatic transport is at the interplay between the immune response and the resolution of inflammation from peripheral tissues, including the artery wall. As vascular complications are a key pathogenic mechanism in COVID-19, leading to inflammation and multiple organ failure, we believe that sustaining lymphatic vessel function should be considered to define optimal CPT. We herein sought to determine what specific COVID-19 convalescent plasma (CCP) characteristics should be considered to limit inflammation-driven lymphatic endothelial cells (LEC) dysfunction. CCP donated 16 to 100 days after the last day of symptoms was characterized and incubated on inflammation-elicited adult human dermal LEC (aHDLEC). Plasma analysis revealed that late donation correlates with higher concentration of circulating pro-inflammatory cytokines. Conversely, extracellular vesicles (EVs) derived from LEC are more abundant in early donated plasma (r = −0.413, p = 0.004). Thus, secretion of LEC-EVs by an impaired endothelium could be an alarm signal that instigate the self-defense of peripheral lymphatic vessels against an excessive inflammation. Indeed, in vitro experiments suggest that CCP obtained rapidly following the onset of symptoms does not damage the aHDLEC junctions as much as late-donated plasma. We identified a particular signature of CCP that would counteract the effects of an excessive inflammation on the lymphatic endothelium. Accordingly, an easy and efficient selection of convalescent plasma based on time of donation would be essential to promote the preservation of the lymphatic and immune system of infected patients.

Characterization of SARS-CoV-2-specific humoral immunity and its potential applications and therapeutic prospects

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an ongoing pandemic that poses a great threat to human health worldwide. As the humoral immune response plays essential roles in disease occurrence and development, understanding the dynamics and characteristics of virus-specific humoral immunity in SARS-CoV-2-infected patients is of great importance for controlling this disease. In this review, we summarize the characteristics of the humoral immune response after SARS-CoV-2 infection and further emphasize the potential applications and therapeutic prospects of SARS-CoV-2-specific humoral immunity and the critical role of this immunity in vaccine development. Notably, serological antibody testing based on the humoral immune response can guide public health measures and control strategies; however, it is not recommended for population surveys in areas with very low prevalence. Existing evidence suggests that asymptomatic individuals have a weaker immune response to SARS-CoV-2 infection, whereas SARS-CoV-2-infected children have a more effective humoral immune response than adults. The correlations between antibody (especially neutralizing antibody) titers and protection against SARS-CoV-2 reinfection should be further examined. In addition, the emergence of cross-reactions among different coronavirus antigens in the development of screening technology and the risk of antibody-dependent enhancement related to SARS-CoV-2 vaccination should be given further attention.

OUP accepted manuscript

Passive antibody immunotherapeutics directed against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are promising countermeasures for protection and treatment of coronavirus disease 2019 (COVID-19). SARS-CoV-2 variants of concern (VOCs) and variants of interest (VOIs) can impact the clinical efficacy of immunotherapeutics. A fully human polyclonal antibody immunotherapeutic purified from plasma of transchromosomic (Tc) bovines hyperimmunized with SARS-CoV-2 WA-1 spike (SAB-185) is being assessed for efficacy in a phase 2/3 clinical trial when different circulating SARS-CoV-2 variants predominated. We evaluated antibody binding, avidity maturation, and SARS-CoV-2 VOCs/VOIs virus-neutralizing capacity of convalescent plasma compared with different lots of SAB-185 and individual Tc bovine sera sequentially obtained after each vaccination against Alpha, Epsilon, Iota, Gamma, Beta, Kappa, and Delta variants. In contrast to convalescent plasma, sera and SAB-185 derived from hyperimmunized Tc bovines demonstrated higher antibody avidity and more potent cross-neutralizing activity of VOCs/VOIs. Thus, SAB-185 is a potential promising therapeutic candidate for the treatment of patients infected with SARS-CoV-2 variants.

Epitope diversity of SARS-CoV-2 hyperimmune intravenous human immunoglobulins and neutralization of variants of concern

Hyperimmune immunoglobulin (hCoV-2IG) generated from SARS-CoV-2 convalescent plasma (CP) are under evaluation in clinical trials. Here we explored the antibody epitope repertoire, and virus neutralizing capacity of six hCoV-2IG batches as well as nine CP against SARS-CoV-2 and emerging variants of concern (VOCs). Epitope-mapping by gene-fragment phage display library spanning the SARS-CoV-2 spike demonstrated broad recognition of multiple antigenic sites spanning the entire spike that was higher for hCoV-2IG than CP, with predominant binding to the fusion peptide. In the pseudovirus neutralization assay and in the wild-type SARS-CoV-2 PRNT assay, hCoV-2IG lots showed higher titers against the WA-1 strain compared with CP. Neutralization of VOCs were reduced to different extent by hCoV-2IG lots but were higher than CP. Significant reduction of hCoV-2IG binding was observed to RBD-E484K followed by RBD-N501Y (but not RBD-K417N). This study suggests that post-exposure treatment with hCoV-2IG could be preferable to CP.

•

SARS-CoV-2 hCoV-2IG demonstrate highly diverse antibody epitope profile

•

SARS-CoV-2 hCoV-2IG lots neutralized SARS-CoV-2 variants better than CP

•

Significant reduction of hCoV-2IG binding to RBD-E484K compared with unmutated RBD

•

Higher hCoV-2IG dose would be required for SARS-CoV-2 variant infected patients

COVID-19 Repeated Convalescent Plasma Collection: Analysis of 149 Donations from 88 French Military Health Workers

BACKGROUND

Passive therapy with convalescent plasma (CP) could be an effective and safe treatment option in COVID-19 patients. Neutralizing antibodies present in CP generated in response to SARS-CoV-2 infection and directed against the receptor-binding domain of the spike protein are considered to play a major role in the viral clearance. CP infusion may also contribute to the modulation of the immune response through its immunomodulatory effect. We describe for the first time the effectiveness of a CP collection protocol from repeated donations in young patients.

MATERIALS AND METHODS

We enrolled health service workers who experienced mild to moderate COVID-19 and from whom several donations have been collected. No minimal severity threshold and no biological cure criteria were required. Donors could return to a second plasma donation 14 days after the first donation. A minimal neutralizing antibody titer of 1:40 was considered for clinical use.

RESULTS

Eighty-eight donors were included (median age 35 [28-48] years, 41 women), and 149 plasma products were collected. COVID-19 were mainly WHO stage 2 infections (96%). Among the 88 first donations, 76% had neutralizing antibody titers higher than or equal to 1:40. Eighty-eight percent of donors who came for a second donation had a neutralizing antibody titer of 1:40. Median durations were 15 (15-19) and 38 (33-46) days from the first to the second donation and from recovery to the second donation, respectively. Sixty-nine percent of donors who came for a third donation had a neutralizing antibody titer of 1:40. Median durations were 16 (13-37) and 54 (49-61) days from the second to the third donation and from recovery to the third donation, respectively. No significant difference was observed between the IgG ratio and the age of the donors or the time between recovery and donation. The average IgG ratio did not significantly vary between donations. When focused on repeated blood donors, no significant differences were observed either.

CONCLUSION

The recruitment of young patients with a mild to moderate CO-VID-19 course is an efficient possibility to collect CP with a satisfactory level of neutralizing antibodies. Repeated donations are a well-tolerated and effective way of CP collection.

Rapid and Flexible Platform To Assess Anti-SARS-CoV-2 Antibody Neutralization and Spike Protein-Specific Antivirals

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is ongoing and has shown the community that flexible methods for rapidly identifying and screening candidate antivirals are needed. Assessing virus-neutralizing activity of human serum to monitor population immunity and response to infection and vaccination is key to pandemic control. We developed a virus neutralization platform strategy that relies only on bioinformatic and genetic information of the virus of interest. The platform uses viral envelope glycoprotein cDNAs to set up an assay that mimics multicycle infection but is safe and, therefore, amenable to biosafety level 2 (BSL2) conditions for viruses that require BSL3 facilities (e.g., SARS-CoV-1 and SARS-CoV-2). As a complement to this platform, we present a new cell-based immunofluorescent (CBI) assay that uses SARS-CoV-2 spike protein (S)-expressing cells to accurately measure the neutralization potential of human sera and is readily adaptable to variants of concern. These methods should be useful additions to the tools for assessing antiviral immunity, whether acquired via natural infection or vaccines.

IMPORTANCE Assays for rapid biosafety level 2 (BSL2) evaluation of neutralizing properties of antibodies acquired via natural infection or through vaccination is urgently needed. Here, we propose a combinatorial approach in which sera are screened for SARS-CoV-2 spike protein (S) binding using a cell-based immunofluorescent (CBI) assay, and positive samples are further evaluated in a pseudotyped viral multicycle infection-mimicking protocol under BSL2 conditions.

Rapid immunoassay and clinical evaluation of the SARS-CoV-2 antibody assay on the real express-6 analyzer

We developed a rapid and simple magnetic chemiluminescence enzyme immunoassay on the Real Express‐6 analyzer, which could simultaneously detect immunoglobulin G and immunoglobulin M antibodies against SARS‐CoV‐2 virus in human blood within 18 min, and which could be used to detect clinical studies to verify its clinical efficacy. We selected blood samples from 185 COVID‐19 patients confirmed by polymerase chain reaction and 271 negative patients to determine the clinical detection sensitivity, specificity, stability, and precision of this method. Meanwhile, we also surveyed the dynamic variance of viral antibodies during SARS‐CoV‐2 infection. This rapid immunoassay test has huge potential benefits for rapid screening of SARS‐CoV‐2 infection and may help clinical drug and vaccine development.

We have developed an immunoluminescencemethod that can detect immunoglobulin G and immunoglobulin M antibodies againstSARS‐CoV‐2 virus.

This detection method cansimultaneously detect IgG and IgM against SARS‐CoV‐2 virus within 18 minutes.

This detection method has highsensitivity, stability and precision, and its specificity is higher than thatof colloidal gold. The dynamic variance of antibodiesdetected by this detection method can be consistent with the clinical CTresults, and can be used as a reference.

COVID-19 is a systemic vascular hemopathy: insight for mechanistic and clinical aspects

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is presenting as a systemic disease associated with vascular inflammation and endothelial injury. Severe forms of SARS-CoV-2 infection induce acute respiratory distress syndrome (ARDS) and there is still an ongoing debate on whether COVID-19 ARDS and its perfusion defect differs from ARDS induced by other causes. Beside pro-inflammatory cytokines (such as interleukin-1 β [IL-1β] or IL-6), several main pathological phenomena have been seen because of endothelial cell (EC) dysfunction: hypercoagulation reflected by fibrin degradation products called D-dimers, micro- and macrothrombosis and pathological angiogenesis. Direct endothelial infection by SARS-CoV-2 is not likely to occur and ACE-2 expression by EC is a matter of debate. Indeed, endothelial damage reported in severely ill patients with COVID-19 could be more likely secondary to infection of neighboring cells and/or a consequence of inflammation. Endotheliopathy could give rise to hypercoagulation by alteration in the levels of different factors such as von Willebrand factor. Other than thrombotic events, pathological angiogenesis is among the recent findings. Overexpression of different proangiogenic factors such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF-2) or placental growth factors (PlGF) have been found in plasma or lung biopsies of COVID-19 patients. Finally, SARS-CoV-2 infection induces an emergency myelopoiesis associated to deregulated immunity and mobilization of endothelial progenitor cells, leading to features of acquired hematological malignancies or cardiovascular disease, which are discussed in this review. Altogether, this review will try to elucidate the pathophysiology of thrombotic complications, pathological angiogenesis and EC dysfunction, allowing better insight in new targets and antithrombotic protocols to better address vascular system dysfunction. Since treating SARS-CoV-2 infection and its potential long-term effects involves targeting the vascular compartment and/or mobilization of immature immune cells, we propose to define COVID-19 and its complications as a systemic vascular acquired hemopathy.

Convalescent Plasma Therapy in the management of COVID-19 patients-The newer dimensions

Background

COVID 19 infection caused by novel coronavirus with no specific established treatment. Convalescent Plasma Therapy has been authorized as an off-label therapeutic procedure. We assessed the outcome of convalescent plasma (CP) units versus standard treatment on the complete recovery, improvement and 28 days’ mortality of COVID 19 patients.

Materials and methods

The present was multi-centric case controlled observational prospective study. The study was conducted for a period of four and half months from July 15 2020 to 30 November 2020 after taking approval from the Expert Committee, Health & Family Welfare Department, Government of Odisha. Plasma therapy was applied on two groups of 1189 serious COVID patients (959 number of pre- critical and 230 number of critical patients) not responding to oxygen therapy. It was compared with non- transfused control group of 1243 patients (996 number of pre-critical and 247 number of critical patients).

Results

Discharge was better in (55.5%) transfused than (43%)in non-transfused pre-critical patients and the mortality was lower (44.3%) in transfused, (48.9%) than non-transfused critical patients respectively. Complete recovery was highest in those who were transfused with CP with neutralizing titer more than 1:160 (52.5%), 18–30 years’ age group (64%), females (53%), ‘O’ Rh D positive blood group (51.5%). There was no adverse reaction due to CP transfusion.

Conclusions

CP is effective in improving the recovery rate with earlier discharge and decrease in the 28 days’ mortality than in the control non-transfused group. CP with neutralizing antibody titer more than 1:160 has the best outcome with complete recovery and decrease in the mortality. It is more effective in treating pre-critical patients when transfused early, in female patients, in younger age group and in blood group ‘O’ Rh D positive.

Impact of convalescent plasma therapy on SARS CoV-2 antibody profile in COVID-19 patients

Convalescent plasma (CP) have been used for treatment of coronavirus disease 2019 (COVID-19), but their effectiveness varies significantly. Moreover, the impact of CP treatment on the composition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in COVID-19 patients and antibody markers that differentiate between those who survive and those who succumb to the COVID-19 disease are not well understood. Herein, we performed longitudinal analysis of antibody profile on 115 sequential plasma samples from 16 hospitalized COVID-19 patients treated with either CP or standard of care, only half of them survived. Differential antibody kinetics was observed for antibody binding, immunoglobulin M/immunoglobulin G/immunoglobulin A (IgM/IgG/IgA) distribution, and affinity maturation in “survived” versus “fatal” COVID-19 patients. Surprisingly, CP treatment did not predict survival. Strikingly, marked decline in neutralization titers was observed in the fatal patients prior to death, and convalescent plasma treatment did not reverse this trend. Furthermore, irrespective of CP treatment, higher antibody affinity to the SARS-CoV-2 prefusion spike was associated with survival outcome. Additionally, sustained elevated IgA response was associated with fatal outcome in these COVID-19 patients. These findings propose that treatment of COVID-19 patients with convalescent plasma should be carefully targeted, and effectiveness of treatment may depend on the clinical and immunological status of COVID-19 patients, as well as the quality of the antibodies in the convalescent plasma.

Use of convalescent plasma for COVID-19 in India: A review & practical guidelines

Convalescent plasma (CP) therapy is one of the promising therapies being tried for COVID-19 patients. This passive immunity mode involves separating preformed antibodies against SARS-CoV-2 from a recently recovered COVID-19 patient and infusing it into a patient with active disease or an exposed individual for prophylaxis. Its advantages include ease of production, rapid deployment, specificity against the target infectious agent, and scalability. In the current pandemic, it has been used on a large scale across the globe and also in India. However, unequivocal proof of efficacy and effectiveness in COVID-19 is still not available. Various CP therapy parameters such as donor selection, antibody quantification, timing of use, and dosing need to be considered before its use. The current review attempts to summarize the available evidence and provide recommendations for setting up CP protocols in clinical and research settings.

Convalescent Plasma for the Prevention and Treatment of COVID-19: A Systematic Review and Quantitative Analysis

BACKGROUND

The COVID-19 pandemic, caused by a novel coronavirus termed SARS-CoV-2, has spread quickly worldwide. Convalescent plasma (CP) obtained from patients following recovery from COVID-19 infection and development of antibodies against the virus is an attractive option for either prophylactic or therapeutic treatment, since antibodies may have direct or indirect antiviral activities and immunotherapy has proven effective in principle and in many clinical reports.

OBJECTIVE

We seek to characterize the latest advances and evidence in the use of CP for COVID-19 through a systematic review and quantitative analysis, identify knowledge gaps in this setting, and offer recommendations and directives for future research.

METHODS

PubMed, Web of Science, and Embase were continuously searched for studies assessing the use of CP for COVID-19, including clinical studies, commentaries, reviews, guidelines or protocols, and in vitro testing of CP antibodies. The screening process and data extraction were performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Quality appraisal of all clinical studies was conducted using a universal tool independent of study designs. A meta-analysis of case-control and randomized controlled trials (RCTs) was conducted using a random-effects model.

RESULTS

Substantial literature has been published covering various aspects of CP therapy for COVID-19. Of the references included in this review, a total of 243 eligible studies including 64 clinical studies, 79 commentary articles, 46 reviews, 19 guidance and protocols, and 35 in vitro testing of CP antibodies matched the criteria. Positive results have been mostly observed so far when using CP for the treatment of COVID-19. There were remarkable heterogeneities in the CP therapy with respect to patient demographics, donor antibody titers, and time and dose of CP administration. The studies assessing the safety of CP treatment reported low incidence of adverse events. Most clinical studies, in particular case reports and case series, had poor quality. Only 1 RCT was of high quality. Randomized and nonrandomized data were found in 2 and 11 studies, respectively, and were included for meta-analysis, suggesting that CP could reduce mortality and increase viral clearance. Despite promising pilot studies, the benefits of CP treatment can only be clearly established through carefully designed RCTs.

CONCLUSIONS

There is developing support for CP therapy, particularly for patients who are critically ill or mechanically ventilated and resistant to antivirals and supportive care. These studies provide important lessons that should inform the planning of well-designed RCTs to generate more robust knowledge for the efficacy of CP in patients with COVID-19. Future research is necessary to fill the knowledge gap regarding prevention and treatment for patients with COVID-19 with CP while other therapeutics are being developed.

Clinical and laboratory evaluation of patients with SARS-CoV-2 pneumonia treated with high-titer convalescent plasma

Here, we report on a phase IIa study to determine the intubation rate, survival, viral clearance, and development of endogenous Abs in patients with COVID-19 pneumonia treated with convalescent plasma (CCP) containing high levels of neutralizing anti-SARS-CoV-2 Abs. Radiographic and laboratory evaluation confirmed all 51 treated patients had COVID-19 pneumonia. Fresh or frozen CCP from donors with high titers of neutralizing Abs was administered. The nonmechanically ventilated patients (n = 36) had an intubation rate of 13.9% and a 30-day survival rate of 88.9%, and the overall survival rate for a comparative group based on network data was 72.5% (1625/2241). Patients had negative nasopharyngeal swab rates of 43.8% and 73.0% on days 10 and 30, respectively. Patients mechanically ventilated had a day-30 mortality rate of 46.7%; the mortality rate for a comparative group based on network data was 71.0% (369/520). All evaluable patients were found to have neutralizing Abs on day 3 (n = 47), and all but 1 patient had Abs on days 30 and 60. The only adverse event was a mild rash. In this study on patients with COVID-19 disease, we show therapeutic use of CCP was safe and conferred transfer of Abs, while preserving endogenous immune response.

The Case for S2: The Potential Benefits of the S2 Subunit of the SARS-CoV-2 Spike Protein as an Immunogen in Fighting the COVID-19 Pandemic

As COVID-19 cases continue to rise, it is imperative to learn more about antibodies and T-cells produced against the causative virus, SARS-CoV-2, in order to guide the rapid development of therapies and vaccines. While much of the current antibody and vaccine research focuses on the receptor-binding domain of S1, a less-recognized opportunity is to harness the potential benefits of the more conserved S2 subunit. Similarities between the spike proteins of both SARS-CoV-2 and HIV-1 warrant exploring S2. Possible benefits of employing S2 in therapies and vaccines include the structural conservation of S2, extant cross-reactive neutralizing antibodies in populations (due to prior exposure to common cold coronaviruses), the steric neutralization potential of antibodies against S2, and the stronger memory B-cell and T-cell responses. More research is necessary on the effect of glycans on the accessibility and stability of S2, SARS-CoV-2 mutants that may affect infectivity, the neutralization potential of antibodies produced by memory B-cells, cross-reactive T-cell responses, antibody-dependent enhancement, and antigen competition. This perspective aims to highlight the evidence for the potential advantages of using S2 as a target of therapy or vaccine design.

Longitudinal antibody repertoire in "mild" versus "severe" COVID-19 patients reveals immune markers associated with disease severity and resolution

Limited knowledge exists on immune markers associated with disease severity or recovery in patients with coronavirus disease 2019 (COVID-19). Here, we elucidated longitudinal evolution of SARS-CoV-2 antibody repertoire in patients with acute COVID-19. Differential kinetics was observed for immunoglobulin M (IgM)/IgG/IgA epitope diversity, antibody binding, and affinity maturation in "severe" versus "mild" COVID-19 patients. IgG profile demonstrated immunodominant antigenic sequences encompassing fusion peptide and receptor binding domain (RBD) in patients with mild COVID-19 who recovered early compared with "fatal" COVID-19 patients. In patients with severe COVID-19, high-titer IgA were observed, primarily against RBD, especially in patients who succumbed to SARS-CoV-2 infection. The patients with mild COVID-19 showed marked increase in antibody affinity maturation to prefusion SARS-CoV-2 spike that associated with faster recovery from COVID-19. This study revealed antibody markers associated with disease severity and resolution of clinical disease that could inform development and evaluation of effective immune-based countermeasures against COVID-19.

Antibody affinity maturation and plasma IgA associate with clinical outcome in hospitalized COVID-19 patients

Hospitalized COVID-19 patients often present with a large spectrum of clinical symptoms. There is a critical need to better understand the immune responses to SARS-CoV-2 that lead to either resolution or exacerbation of the clinical disease. Here, we examine longitudinal plasma samples from hospitalized COVID-19 patients with differential clinical outcome. We perform immune-repertoire analysis including cytokine, hACE2-receptor inhibition, neutralization titers, antibody epitope repertoire, antibody kinetics, antibody isotype and antibody affinity maturation against the SARS-CoV-2 prefusion spike protein. Fatal cases demonstrate high plasma levels of IL-6, IL-8, TNFα, and MCP-1, and sustained high percentage of IgA-binding antibodies to prefusion spike compared with non-ICU survivors. Disease resolution in non-ICU and ICU patients associates with antibody binding to the receptor binding motif and fusion peptide, and antibody affinity maturation to SARS-CoV-2 prefusion spike protein. Here, we provide insight into the immune parameters associated with clinical disease severity and disease-resolution outcome in hospitalized patients that could inform development of vaccine/therapeutics against COVID-19.

SARS-CoV2 infection has been linked to a wide range of clinical severities and the immunopathology is still under intense scrutiny. Here, the authors uncover an association of antibody affinity maturation and plasma IgA levels with clinical outcome in patients with COVID-19 disease.

Optimization of hydroxychloroquine dosing scheme based on COVID-19 patients' characteristics: a review of the literature and simulations

During the recent COVID-19 outbreak hydroxychloroquine (HCQ) has been proposed as a safe and effective therapeutic option. However, a wide variety of dosing schemes has been applied in the clinical practice and tested in clinical studies. An extended literature survey was performed investigating the pharmacokinetics, the efficacy and safety of HCQ in COVID-19 treatment. Population pharmacokinetic models were retrieved from the literature and after evaluation and assessment one was selected in order to perform simulations. The most commonly applied dosing schemes were explored for patients with different weights and different levels of HCQ clearance impairment. Model-based simulations of HCQ concentrations revealed that high initial doses followed by low and sparse doses may offer significant benefits to patients by decreasing the viral load without reaching levels considered to produce adverse effects. For instance, the dosing scheme proposed for a 70 kg adult with moderate COVID-19 symptoms would be 600 mg upon diagnosis, 400 mg after 12 h, 300 mg after 24 h, 200 mg after 36 h, followed by 200 mg BID for 4 d, followed by 200 mg OD for 5 d. Based on the results from simulations performed and the currently published knowledge regarding HCQ in COVID-19 treatment, this study provides evidence that a high loading dose followed by sparse doses could offer significant benefits to the patients.

Correlates of protection against SARS-CoV-2 in rhesus macaques

Recent studies have reported the protective efficacy of both natural1 and vaccine-induced2-7 immunity against challenge with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in rhesus macaques. However, the importance of humoral and cellular immunity for protection against infection with SARS-CoV-2 remains to be determined. Here we show that the adoptive transfer of purified IgG from convalescent rhesus macaques (Macaca mulatta) protects naive recipient macaques against challenge with SARS-CoV-2 in a dose-dependent fashion. Depletion of CD8+ T cells in convalescent macaques partially abrogated the protective efficacy of natural immunity against rechallenge with SARS-CoV-2, which suggests a role for cellular immunity in the context of waning or subprotective antibody titres. These data demonstrate that relatively low antibody titres are sufficient for protection against SARS-CoV-2 in rhesus macaques, and that cellular immune responses may contribute to protection if antibody responses are suboptimal. We also show that higher antibody titres are required for treatment of SARS-CoV-2 infection in macaques. These findings have implications for the development of SARS-CoV-2 vaccines and immune-based therapeutic agents.

The Assessment of Convalescent Plasma Efficacy against COVID-19

Antibody-based therapy for infectious diseases predates modern antibiotics and, in the absence of other therapeutic options, was deployed early in the SARS-CoV-2 pandemic through COVID-19 convalescent plasma (CCP) administration. Although most studies have demonstrated signals of efficacy for CCP, definitive assessment has proved difficult under pandemic conditions, with rapid changes in disease incidence and the knowledge base complicating the design and implementation of randomized controlled trials. Nevertheless, evidence from a variety of studies demonstrates that CCP is as safe as ordinary plasma and strongly suggests that it can reduce mortality if given early and with sufficient antibody content.

COVID-19 treatments and pathogenesis including anosmia in K18-hACE2 mice

The ongoing coronavirus disease 2019 (COVID-19) pandemic is associated with substantial morbidity and mortality. Although much has been learned in the first few months of the pandemic, many features of COVID-19 pathogenesis remain to be determined. For example, anosmia is a common presentation, and many patients with anosmia show no or only minor respiratory symptoms¹. Studies in animals infected experimentally with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of COVID-19, provide opportunities to study aspects of the disease that are not easily investigated in human patients. Although the severity of COVID-19 ranges from asymptomatic to lethal², most experimental infections provide insights into mild disease³. Here, using K18-hACE2 transgenic mice that were originally developed for SARS studies⁴, we show that infection with SARS-CoV-2 causes severe disease in the lung and, in some mice, the brain. Evidence of thrombosis and vasculitis was detected in mice with severe pneumonia. Furthermore, we show that infusion of convalescent plasma from a recovered patient with COVID-19 protected against lethal disease. Mice developed anosmia at early time points after infection. Notably, although pre-treatment with convalescent plasma prevented most signs of clinical disease, it did not prevent anosmia. Thus, K18-hACE2 mice provide a useful model for studying the pathological basis of both mild and lethal COVID-19 and for assessing therapeutic interventions.

Convalescent plasma in the management of moderate covid-19 in adults in India: open label phase II multicentre randomised controlled trial (PLACID Trial)

OBJECTIVE

To investigate the effectiveness of using convalescent plasma to treat moderate coronavirus disease 2019 (covid-19) in adults in India.

DESIGN

Open label, parallel arm, phase II, multicentre, randomised controlled trial.

SETTING

39 public and private hospitals across India.

PARTICIPANTS

464 adults (≥18 years) admitted to hospital (screened 22 April to 14 July 2020) with confirmed moderate covid-19 (partial pressure of oxygen in arterial blood/fraction of inspired oxygen (PaO₂/FiO₂) ratio between 200 mm Hg and 300 mm Hg or a respiratory rate of more than 24/min with oxygen saturation 93% or less on room air): 235 were assigned to convalescent plasma with best standard of care (intervention arm) and 229 to best standard of care only (control arm).

INTERVENTIONS

Participants in the intervention arm received two doses of 200 mL convalescent plasma, transfused 24 hours apart. The presence and levels of neutralising antibodies were not measured a priori; stored samples were assayed at the end of the study.

MAIN OUTCOME MEASURE

Composite of progression to severe disease (PaO₂/FiO₂ <100 mm Hg) or all cause mortality at 28 days post-enrolment.

RESULTS

Progression to severe disease or all cause mortality at 28 days after enrolment occurred in 44 (19%) participants in the intervention arm and 41 (18%) in the control arm (risk difference 0.008 (95% confidence interval -0.062 to 0.078); risk ratio 1.04, 95% confidence interval 0.71 to 1.54).

CONCLUSION

Convalescent plasma was not associated with a reduction in progression to severe covid-19 or all cause mortality. This trial has high generalisability and approximates convalescent plasma use in real life settings with limited laboratory capacity. A priori measurement of neutralising antibody titres in donors and participants might further clarify the role of convalescent plasma in the management of covid-19.

TRIAL REGISTRATION

Clinical Trial Registry of India CTRI/2020/04/024775.

Rapid Antibody-Based COVID-19 Mass Surveillance: Relevance, Challenges, and Prospects in a Pandemic and Post-Pandemic World

The aggressive outbreak of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) as COVID-19 (coronavirus disease-2019) pandemic demands rapid and simplified testing tools for its effective management. Increased mass testing and surveillance are crucial for controlling the disease spread, obtaining better pandemic statistics, and developing realistic epidemiological models. Despite the advantages of nucleic acid- and antigen-based tests such as accuracy, specificity, and non-invasive approaches of sample collection, they can only detect active infections. Antibodies (immunoglobulins) are produced by the host immune system within a few days after infection and persist in the blood for at least several weeks after infection resolution. Antibody-based tests have provided a substitute and effective method of ultra-rapid detection for multiple contagious disease outbreaks in the past, including viral diseases such as SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). Thus, although not highly suitable for early diagnosis, antibody-based methods can be utilized to detect past infections hidden in the population, including asymptomatic ones. In an active community spread scenario of a disease that can provide a bigger window for mass detections and a practical approach for continuous surveillance. These factors encouraged researchers to investigate means of improving antibody-based rapid tests and employ them as reliable, reproducible, sensitive, specific, and economic tools for COVID-19 mass testing and surveillance. The development and integration of such immunoglobulin-based tests can transform the pandemic diagnosis by moving the same out of the clinics and laboratories into community testing sites and homes. This review discusses the principle, technology, and strategies being used in antibody-based testing at present. It also underlines the immense prospect of immunoglobulin-based testing and the efficacy of repeated planned deployment in pandemic management and post-pandemic sustainable screenings globally.

Pharmaco-Immunomodulatory Therapy in COVID-19

The severe acute respiratory syndrome coronavirus 2 associated coronavirus disease 2019 (COVID-19) illness is a syndrome of viral replication in concert with a host inflammatory response. The cytokine storm and viral evasion of cellular immune responses may play an equally important role in the pathogenesis, clinical manifestation, and outcomes of COVID-19. Systemic proinflammatory cytokines and biomarkers are elevated as the disease progresses towards its advanced stages, and correlate with worse chances of survival. Immune modulators have the potential to inhibit cytokines and treat the cytokine storm. A literature search using PubMed, Google Scholar, and ClinicalTrials.gov was conducted through 8 July 2020 using the search terms ‘coronavirus’, ‘immunology’, ‘cytokine storm’, ‘immunomodulators’, ‘pharmacology’, ‘severe acute respiratory syndrome 2’, ‘SARS-CoV-2’, and ‘COVID-19’. Specific immune modulators include anti-cytokines such as interleukin (IL)-1 and IL-6 receptor antagonists (e.g. anakinra, tocilizumab, sarilumab, siltuximab), Janus kinase (JAK) inhibitors (e.g. baricitinib, ruxolitinib), anti-tumor necrosis factor-α (e.g. adalimumab, infliximab), granulocyte–macrophage colony-stimulating factors (e.g. gimsilumab, lenzilumab, namilumab), and convalescent plasma, with promising to negative trials and other data. Non-specific immune modulators include human immunoglobulin, corticosteroids such as dexamethasone, interferons, statins, angiotensin pathway modulators, macrolides (e.g. azithromycin, clarithromycin), hydroxychloroquine and chloroquine, colchicine, and prostaglandin D2 modulators such as ramatroban. Dexamethasone 6 mg once daily (either by mouth or by intravenous injection) for 10 days may result in a reduction in mortality in COVID-19 patients by one-third for patients on ventilators, and by one-fifth for those receiving oxygen. Research efforts should focus not only on the most relevant immunomodulatory strategies but also on the optimal timing of such interventions to maximize therapeutic outcomes. In this review, we discuss the potential role and safety of these agents in the management of severe COVID-19, and their impact on survival and clinical symptoms.

The HMOX1 Pathway as a Promising Target for the Treatment and Prevention of SARS-CoV-2 of 2019 (COVID-19)

The coronavirus disease of 2019 (COVID-19) or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a global pandemic with increasing incidence and mortality rates. Recent evidence based on the cytokine profiles of severe COVID-19 cases suggests an overstimulation of macrophages and monocytes associated with reduced T-cell abundance (lymphopenia) in patients infected with SARS-CoV-2. The SARS-CoV-2 open reading frame 3 a (ORF3a) protein was found to bind to the human HMOX1 protein at a high confidence through high-throughput screening experiments. The HMOX1 pathway can inhibit platelet aggregation, and can have anti-thrombotic and anti-inflammatory properties, amongst others, all of which are critical medical conditions observed in COVID-19 patients. Here, we review the potential of modulating the HMOX1-ORF3a nexus to regulate the innate immune response for therapeutic benefits in COVID-19 patients. We also review other potential treatment strategies and suggest novel synthetic and natural compounds that may have the potential for future development in clinic.

Compassionate use of convalescent plasma for treatment of moderate and severe pneumonia in COVID-19 patients and association with IgG antibody levels in donated plasma

BACKGROUND

We assessed outcome of patients with moderate and severe COVID-19 following treatment with convalescent plasma (CP) and the association with IgG levels in transfused CP.

METHODS

A prospective cohort study. Primary outcome was improvement at day 14 defined as alive, not on mechanical ventilation, and moderate, mild, or recovered from COVID-19. Antibody levels in CP units were unknown at the time of treatment. IgG against the spike protein S1 was subsequently measured by ELISA. Neutralizing antibodies titers were determined in a subset. Outcome was assessed in relation to the mean antibody level transfused to the patients (≤4.0 versus >4.0).

FINDINGS

Of 49 patients, 11 (22.4%) had moderate, 38 (77.6%) had severe disease, 28 were ventilated. At day 14, 24 (49.0%) patients improved, 9 (18.4%) died, and 13 (26.5%) were ventilated. In 14/98 (14.3%) CP units IgG was < 1.1 (cutoff calibration) and in 60 (61.2%) ≤4.0. IgG level and neutralizing antibody titer were correlated (0.85 p < 0.001). In patients receiving ≤4.0 antibody levels, 11/30 improved (36.7%) versus 13/19 (68.4%) in patients receiving >4.0 odds ratio (OR) 0.267 [95% confidence interval (CI) 0.079-0.905], P = 0.030. In patients diagnosed >10 days prior to treatment, 4/14 (22.4%) improved in the ≤4.0 antibody group, versus 6/7 (85.7%) in the >4.0 antibody group, OR 0.048 (95% CI, 0.004-0.520), P = 0.007. No serious adverse events were reported.

INTERPRETATION

Treatment with CP with higher levels of IgG against S1 may benefit patients with moderate and severe COVID-19. IgG against S1 level in CP predicts neutralization antibodies titers.

Potent neutralizing equine antibodies raised against recombinant SARS-CoV-2 spike protein for COVID-19 passive immunization therapy.. [PMID: 0 DOI: 10.1101/2020.08.17.254375]

We used the trimeric spike (S) glycoprotein (residues 1-1208) in the prefusion conformation to immunize horses for production of hyperimmune globulins against SARS-CoV-2. Serum antibody titers measured by anti-spike ELISA were above 1:1,000,000, and neutralizing antibody titer was 1:14,604 (average PRNT90), which is 140-fold higher than the average neutralizing titer of plasma from three convalescent COVID-19 patients analyzed for comparison. Using the same technology routinely used for industrial production of other horse hyperimmune products, plasma from immunized animals was pepsin digested to remove the Fc portion and purified, yielding a F(ab’)2 preparation with PRNT90 titers 150-fold higher than the neutralizing titers in human convalescent plasma. Repeating the hyperimmunization in a second group of horses confirmed the very high neutralizing titers in serum and in a GMP clinical F(ab’)2 lot. Virus-neutralizing activity in samples from mice that received the F(ab’)2 preparation was detected even three days after injection, indicating an appropriate half-life for therapeutic intervention. These results supported the design of a clinical trial (identifier NCT04573855) to evaluate safety and efficacy of this horse F(ab’)2 preparation.

The role of IgG Fc receptors in antibody-dependent enhancement

Antibody-dependent enhancement (ADE) is a mechanism by which the pathogenesis of certain viral infections is enhanced in the presence of sub-neutralizing or cross-reactive non-neutralizing antiviral antibodies. In vitro modelling of ADE has attributed enhanced pathogenesis to Fcγ receptor (FcγR)-mediated viral entry, rather than canonical viral receptor-mediated entry. However, the putative FcγR-dependent mechanisms of ADE overlap with the role of these receptors in mediating antiviral protection in various viral infections, necessitating a detailed understanding of how this diverse family of receptors functions in protection and pathogenesis. Here, we discuss the diversity of immune responses mediated upon FcγR engagement and review the available experimental evidence supporting the role of FcγRs in antiviral protection and pathogenesis through ADE. We explore FcγR engagement in the context of a range of different viral infections, including dengue virus and SARS-CoV, and consider ADE in the context of the ongoing SARS-CoV-2 pandemic.

Antibody-dependent enhancement (ADE) has been described as a mechanism that contributes to the pathogenesis of dengue virus infection. Limited evidence also suggests that it can also occur in other viral infections. Here, the authors explore the history of the ADE phenomenon, discuss the diversity of Fc effector functions and consider its potential relevance in the context of SARS-CoV-2 infection.

K18-hACE2 Mice for Studies of COVID-19 Treatments and Pathogenesis Including Anosmia

The ongoing COVID-19 pandemic is associated with substantial morbidity and mortality. While much has been learned in the first months of the pandemic, many features of COVID-19 pathogenesis remain to be determined. For example, anosmia is a common presentation and many patients with this finding show no or only minor respiratory signs. Studies in animals experimentally infected with SARS-CoV-2, the cause of COVID-19, provide opportunities to study aspects of the disease not easily investigated in human patients. COVID-19 severity ranges from asymptomatic to lethal. Most experimental infections provide insights into mild disease. Here, using K18-hACE2 mice that we originally developed for SARS studies, we show that infection with SARS-CoV-2 causes severe disease in the lung, and in some mice, the brain. Evidence of thrombosis and vasculitis was detected in mice with severe pneumonia. Further, we show that infusion of convalescent plasma (CP) from a recovered COVID-19 patient provided protection against lethal disease. Mice developed anosmia at early times after infection. Notably, while treatment with CP prevented significant clinical disease, it did not prevent anosmia. Thus K18-hACE2 mice provide a useful model for studying the pathological underpinnings of both mild and lethal COVID-19 and for assessing therapeutic interventions.