Antibody-dependent SARS coronavirus infection is mediated by antibodies against spike proteins

Efficient signal sequence of mRNA vaccines enhances the antigen expression to expand the immune protection against viral infection

The signal sequence played a crucial role in the efficacy of mRNA vaccines against virus pandemic by influencing antigen translation. However, limited research had been conducted to compare and analyze the specific mechanisms involved. In this study, a novel approach was introduced by substituting the signal sequence of the mRNA antigen to enhance its immune response. Computational simulations demonstrated that various signal peptides differed in their binding capacities with the signal recognition particle (SRP) 54 M subunit, which positively correlated with antigen translation efficiency. Our data revealed that the signal sequences of tPA and IL-6-modified receptor binding domain (RBD) mRNA vaccines sequentially led to higher antigen expression and elicited more robust humoral and cellular immune protection against the SARS-CoV-2 compared to the original signal sequence. By highlighting the importance of the signal sequence, this research provided a foundational and safe approach for ongoing modifications in signal sequence-antigen design, aiming to optimize the efficacy of mRNA vaccines.

Immune Response to an Inactivated Vaccine of SARS-CoV-2 (CoronaVac) in an Indigenous Brazilian Population: A Cohort Study

INTRODUCTION

Although the adaptive immune responses to the CoronaVac vaccine are known, their dynamics in indigenous communities remain unclear. In this study, we assessed the humoral and cellular immune responses to CoronaVac (Sinovac Biotech Life Sciences, 2021 NCT05225285, Beijing, China), in immunized Brazilian indigenous individuals.

METHODS

We conducted a prospective cohort study on indigenous Brazilian people between February 2021 and June 2021. Analyses of immune responses were carried out before (T1) and after a vaccination schedule was completed (T2). Demographic data were collected using a questionnaire.

RESULTS

We initially included 328 patients; among them, 120 (36.6%) had no SARS-CoV-2 antibodies. Peripheral blood mononuclear cells (PBMCs) were collected from 106 patients during follow-up visits, of which 91 samples were analyzed by immunophenotyping assay to detect SARS-CoV-2-specific memory T-cell response. Post-vaccination, the levels of memory B-cells and Natural Killer T-lymphocytes increased. Bororó village residents, females, and Terena ethnic group members had higher levels of anti-spike IgG antibodies post-vaccination, whereas alcohol and tobacco users had lower concentrations.

CONCLUSIONS

To our best knowledge, this was the first comprehensive assessment of antibody and T-cell responses against CoronaVac vaccination in indigenous patients. Our findings showed that antibody response and T-cell immunity against SARS-CoV-2 were present in most patients following the vaccination schedule.

Function and mechanism of bispecific antibodies targeting SARS-CoV-2

As the dynamic evolution of SARS-CoV-2 led to reduced efficacy in monoclonal neutralizing antibodies and emergence of immune escape, the role of bispecific antibodies becomes crucial in bolstering antiviral activity and suppressing immune evasion. This review extensively assesses a spectrum of representative bispecific antibodies targeting SARS-CoV-2, delving into their characteristics, design formats, mechanisms of action, and associated advantages and limitations. The analysis encompasses factors influencing the selection of parental antibodies and strategies for incorporating added benefits in bispecific antibody design. Furthermore, how different classes of parental antibodies contribute to augmenting the broad-spectrum neutralization capability within bispecific antibodies is discussed. In summary, this review presents analyses and discussions aimed at offering valuable insights for shaping future strategies in bispecific antibody design to effectively confront the challenges posed by SARS-CoV-2 and propel advancements in antiviral therapeutic development.

Immunoglobulin A response to SARS-CoV-2 infection and immunity

The novel coronavirus disease (COVID-19) and its infamous "Variants" of the etiological agent termed Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) has proven to be a global health concern. The three antibodies, IgA, IgM, and IgG, perform their dedicated role as main workhorses of the host adaptive immune system in virus neutralization. Immunoglobulin-A (IgA), also known as "Mucosal Immunoglobulin", has been under keen interest throughout the viral infection cycle. Its importance lies because IgA is predominant mucosal antibody and SARS family viruses primarily infect the mucosal surfaces of human respiratory tract. Therefore, IgA can be considered a diagnostic and prognostic marker and an active infection biomarker for SARS CoV-2 infection. Along with molecular analyses, serological tests, including IgA detection tests, are gaining ground in application as an early detectable marker and as a minimally invasive detection strategy. In the current review, it was emphasized the role of IgA response in diagnosis, host defense strategies, treatment, and prevention of SARS-CoV-2 infection. The data analysis was performed through almost 100 published peer-reviewed research reports and comprehended the importance of IgA in antiviral immunity against SARS-CoV-2 and other related respiratory viruses. Taken together, it is concluded that secretory IgA- Abs can serve as a promising detection tool for respiratory viral diagnosis and treatment parallel to IgG-based therapeutics and diagnostics. Vaccine candidates that target and trigger mucosal immune response may also be employed in future dimensions of research against other respiratory viruses.

Passive antibody therapy in emerging infectious diseases

The epidemic of corona virus disease 2019 (COVID-19) caused by severe acute respiratory syndrome Coronavirus 2 and its variants of concern (VOCs) has been ongoing for over 3 years. Antibody therapies encompassing convalescent plasma, hyperimmunoglobulin, and neutralizing monoclonal antibodies (mAbs) applied in passive immunotherapy have yielded positive outcomes and played a crucial role in the early COVID-19 treatment. In this review, the development path, action mechanism, clinical research results, challenges, and safety profile associated with the use of COVID-19 convalescent plasma, hyperimmunoglobulin, and mAbs were summarized. In addition, the prospects of applying antibody therapy against VOCs was assessed, offering insights into the coping strategies for facing new infectious disease outbreaks.

Immunosenescence and Inflammaging in COVID-19

Despite knowledge gaps in understanding the full spectrum of the hyperinflammatory phase caused by SARS-CoV-2, according to the World Health Organization (WHO), COVID-19 is still the leading cause of death worldwide. Susceptible people to severe COVID-19 are those with underlying medical conditions or those with dysregulated and senescence-associated immune responses. As the immune system undergoes aging in the elderly, such drastic changes predispose them to various diseases and affect their responsiveness to infections, as seen in COVID-19. At-risk groups experience poor prognosis in terms of disease recovery. Changes in the quantity and quality of immune cell function have been described in numerous literature sites. Impaired immune cell function along with age-related metabolic changes can lead to features such as hyperinflammatory response, immunosenescence, and inflammaging in COVID-19. Inflammaging is related to the increased activity of the most inflammatory factors and is the main cause of age-related diseases and tissue failure in the elderly. Since hyperinflammation is a common feature of most severe cases of COVID-19, this pathway, which is not fully understood, leads to immunosenescence and inflammaging in some individuals, especially in the elderly and those with comorbidities. In this review, we shed some light on the age-related abnormalities of innate and adaptive immune cells and how hyperinflammatory immune responses contribute to the inflammaging process, leading to clinical deterioration. Further, we provide insights into immunomodulation-based therapeutic approaches, which are potentially important considerations in vaccine design for elderly populations.

Modeling the emergence of viral resistance for SARS-CoV-2 during treatment with an anti-spike monoclonal antibody

The COVID-19 pandemic has led to over 760 million cases and 6.9 million deaths worldwide. To mitigate the loss of lives, emergency use authorization was given to several anti-SARS-CoV-2 monoclonal antibody (mAb) therapies for the treatment of mild-to-moderate COVID-19 in patients with a high risk of progressing to severe disease. Monoclonal antibodies used to treat SARS-CoV-2 target the spike protein of the virus and block its ability to enter and infect target cells. Monoclonal antibody therapy can thus accelerate the decline in viral load and lower hospitalization rates among high-risk patients with susceptible variants. However, viral resistance has been observed, in some cases leading to a transient viral rebound that can be as large as 3-4 orders of magnitude. As mAbs represent a proven treatment choice for SARS-CoV-2 and other viral infections, evaluation of treatment-emergent mAb resistance can help uncover underlying pathobiology of SARS-CoV-2 infection and may also help in the development of the next generation of mAb therapies. Although resistance can be expected, the large rebounds observed are much more difficult to explain. We hypothesize replenishment of target cells is necessary to generate the high transient viral rebound. Thus, we formulated two models with different mechanisms for target cell replenishment (homeostatic proliferation and return from an innate immune response anti-viral state) and fit them to data from persons with SARS-CoV-2 treated with a mAb. We showed that both models can explain the emergence of resistant virus associated with high transient viral rebounds. We found that variations in the target cell supply rate and adaptive immunity parameters have a strong impact on the magnitude or observability of the viral rebound associated with the emergence of resistant virus. Both variations in target cell supply rate and adaptive immunity parameters may explain why only some individuals develop observable transient resistant viral rebound. Our study highlights the conditions that can lead to resistance and subsequent viral rebound in mAb treatments during acute infection.

In Vitro Antibody-Dependent Enhancement of SARS-CoV-2 Infection Could Be Abolished by Adding Human IgG

Evidence of antibody-dependent enhancement (ADE) of other viruses has raised concerns about the safety of SARS-CoV-2 vaccines and antibody therapeutics. In vitro studies have shown ADE of SARS-CoV-2 infection. In this study, we also found that vaccination/convalescent sera and some approved monoclonal antibodies can enhance SARS-CoV-2 infection of FcR-expressing B cells in vitro. However, the enhancement of SARS-CoV-2 infection can be prevented by blocking Fc-FcR interaction through the addition of human serum/IgG or the introduction of mutations in the Fc portion of the antibody. It should be noted that ADE activity observed on FcR-expressing cells in vitro may not necessarily reflect the situation in vivo; therefore, animal and clinical data should be included for ADE evaluation.

Refinement of an ovine-based immunoglobulin therapy against SARS-CoV-2, with comparison of whole IgG versus F(ab')2 fragments

The development of new therapies against SARS-CoV-2 is required to extend the toolkit of intervention strategies to combat the global pandemic. In this study, hyperimmune plasma from sheep immunised with whole spike SARS-CoV-2 recombinant protein has been used to generate candidate products. In addition to purified IgG, we have refined candidate therapies by removing non-specific IgG via affinity binding along with fragmentation to eliminate the Fc region to create F(ab')2 fragments. These preparations were evaluated for in vitro activity and demonstrated to be strongly neutralising against a range of SARS-CoV-2 strains, including Omicron B2.2. In addition, their protection against disease manifestations and viral loads were assessed using a hamster SARS-CoV-2 infection model. Results demonstrated protective effects of both IgG and F(ab')2, with the latter requiring sequential dosing to maintain in vivo activity due to rapid clearance from the circulation.

Antibody-Dependent Enhancement with a Focus on SARS-CoV-2 and Anti-Glycan Antibodies

Antibody-dependent enhancement (ADE) is a phenomenon where virus-specific antibodies paradoxically cause enhanced viral replication and/or excessive immune responses, leading to infection exacerbation, tissue damage, and multiple organ failure. ADE has been observed in many viral infections and is supposed to complicate the course of COVID-19. However, the evidence is insufficient. Since no specific laboratory markers have been described, the prediction and confirmation of ADE are very challenging. The only possible predictor is the presence of already existing (after previous infection) antibodies that can bind to viral epitopes and promote the disease enhancement. At the same time, the virus-specific antibodies are also a part of immune response against a pathogen. These opposite effects of antibodies make ADE research controversial. The assignment of immunoglobulins to ADE-associated or virus neutralizing is based on their affinity, avidity, and content in blood. However, these criteria are not clearly defined. Another debatable issue (rather terminological, but no less important) is that in most publications about ADE, all immunoglobulins produced by the immune system against pathogens are qualified as pre-existing antibodies, thus ignoring the conventional use of this term for natural antibodies produced without any stimulation by pathogens. Anti-glycan antibodies (AGA) make up a significant part of the natural immunoglobulins pool, and there is some evidence of their antiviral effect, particularly in COVID-19. AGA have been shown to be involved in ADE in bacterial infections, but their role in the development of ADE in viral infections has not been studied. This review focuses on pros and cons for AGA as an ADE trigger. We also present the results of our pilot studies, suggesting that AGAs, which bind to complex epitopes (glycan plus something else in tight proximity), may be involved in the development of the ADE phenomenon.

RDE Treatment Prevents Non-Specific Detection of SARS-CoV-2- and Influenza-Specific IgG Antibodies in Heat-Inactivated Serum Samples

Assessing the levels of serum IgG antibodies is widely used to measure immunity to influenza and the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after natural infection or vaccination with specific vaccines, as well as to study immune responses to these viruses in animal models. For safety reasons, sometimes serum specimens collected from infected individuals are subjected to heat inactivation at 56 °C to reduce the risk of infecting personnel during serological studies. However, this procedure may affect the level of virus-specific antibodies, making the results of antibody immunoassays uninterpretable. Here, we evaluated the effect of the heat inactivation of human, ferret and hamster serum samples on the binding of IgG antibodies to the influenza and SARS-CoV-2 antigens. For this, serum samples of naive and immune hosts were analyzed in three variants: (i) untreated sera, (ii) heated at 56 °C for 1 h, and (iii) treated with receptor-destroying enzyme (RDE). The samples were studied through an in-house enzyme-linked immunosorbent assay (ELISA) using whole influenza virus or recombinant proteins corresponding to nucleocapsid (N) protein and the receptor-binding domain of SARS-CoV-2 Spike (RBD) as antigens. We demonstrated that the heat inactivation of the naive serum samples of various hosts can lead to false-positive results, while RDE treatment abolished the effect of the non-specific binding of IgG antibodies to the viral antigens. Furthermore, RDE also significantly decreased the level of virus-specific IgG antibodies in SARS-CoV-2 and influenza-immune sera of humans and animals, although it is unknown whether it actually removes true virus-specific IgG antibodies or only non-specifically binding artifacts. Nevertheless, we suggest that the RDE treatment of human and animal sera may be useful in preventing false-positive results in various immunoassays, while also neutralizing infectious virus, since the standard protocol for the use of RDE also includes heating the sample at 56 °C.

Serological Evaluation of Antibody Titers After Vaccination Against COVID-19 in 18-44-Year-Old Individuals at a Tertiary Care Center

Background The evaluation of the effectiveness of the vaccines (ChAdOx1-nCOV; Covishield and BBV-152; Covaxin) against coronavirus disease 2019 (COVID-19) is necessary to assess their efficacy. Because most antibodies that neutralize the coronavirus are directed against the receptor binding domain within the spike protein of the virus, these antibodies serve as markers for viral neutralizers and, in turn, for vaccine response. The present study aimed to evaluate the anti-neutralizing antibody (receptor binding domain (RBD)) and immunoglobulin G2 (IgG2) titers following the completion of the vaccination schedule (both vaccines) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methodology In this longitudinal prospective study, conducted in a tertiary care center, 30 sequentially (two doses) vaccinated study participants between the ages of 18 and 44 years were sampled for estimation of anti-RBD antibody titer and IgG2. All statistical analysis was done using SPSS version 20 (IBM Corp., Armonk, NY, USA). P-values less than 0.05 were considered significant. Results There was a statistically significant increase in the neutralizing antibody titer after one month of the second dose (z = -4.597, p < 0.001), while a significant decrease was seen in the IgG2 levels (z = -3.075, p = 0.002). The results showed a significant neutralizing effect of the vaccines being used, with Covishield being more effective than Covaxin. The levels of neutralizing antibodies were independent of all demographic variables such as age, sex, and body mass index. Conclusions This study evaluating the efficacy of the two vaccines, namely, Covishield and Covaxin, is the first of its kind in the state of Chhattisgarh. The results of this study are similar to previous studies conducted in India and outside India, concluding that Covishield is a more effective vaccine.

Neutralizing and Enhancing Epitopes of the SARS-CoV-2 Receptor-Binding Domain (RBD) Identified by Nanobodies

Engineered nanobodies (VHs) to the SARS-CoV-2 receptor-binding domain (RBD) were generated using phage display technology. A recombinant Wuhan RBD served as bait in phage panning to fish out nanobody-displaying phages from a VH/VHH phage display library. Sixteen phage-infected E. coli clones produced nanobodies with 81.79-98.96% framework similarity to human antibodies; thus, they may be regarded as human nanobodies. Nanobodies of E. coli clones 114 and 278 neutralized SARS-CoV-2 infectivity in a dose-dependent manner; nanobodies of clones 103 and 105 enhanced the virus's infectivity by increasing the cytopathic effect (CPE) in an infected Vero E6 monolayer. These four nanobodies also bound to recombinant Delta and Omicron RBDs and native SARS-CoV-2 spike proteins. The neutralizing VH114 epitope contains the previously reported VYAWN motif (Wuhan RBD residues 350-354). The linear epitope of neutralizing VH278 at Wuhan RBD 319RVQPTESIVRFPNITN334 is novel. In this study, for the first time, we report SARS-CoV-2 RBD-enhancing epitopes, i.e., a linear VH103 epitope at RBD residues 359NCVADVSVLYNSAPFFTFKCYG380, and the VH105 epitope, most likely conformational and formed by residues in three RBD regions that are spatially juxtaposed upon the protein folding. Data obtained in this way are useful for the rational design of subunit SARS-CoV-2 vaccines that should be devoid of enhancing epitopes. VH114 and VH278 should be tested further for clinical use against COVID-19.

Design and Immunogenicity of SARS-CoV-2 DNA Vaccine Encoding RBD-PVXCP Fusion Protein

The potential of immune-evasive mutation accumulation in the SARS-CoV-2 virus has led to its rapid spread, causing over 600 million confirmed cases and more than 6.5 million confirmed deaths. The huge demand for the rapid development and deployment of low-cost and effective vaccines against emerging variants has renewed interest in DNA vaccine technology. Here, we report the rapid generation and immunological evaluation of novel DNA vaccine candidates against the Wuhan-Hu-1 and Omicron variants based on the RBD protein fused with the Potato virus X coat protein (PVXCP). The delivery of DNA vaccines using electroporation in a two-dose regimen induced high-antibody titers and profound cellular responses in mice. The antibody titers induced against the Omicron variant of the vaccine were sufficient for effective protection against both Omicron and Wuhan-Hu-1 virus infections. The PVXCP protein in the vaccine construct shifted the immune response to the favorable Th1-like type and provided the oligomerization of RBD-PVXCP protein. Naked DNA delivery by needle-free injection allowed us to achieve antibody titers comparable with mRNA-LNP delivery in rabbits. These data identify the RBD-PVXCP DNA vaccine platform as a promising solution for robust and effective SARS-CoV-2 protection, supporting further translational study.

Convalescent plasma for people with COVID-19: a living systematic review

BACKGROUND

Convalescent plasma may reduce mortality in patients with viral respiratory diseases, and is being investigated as a potential therapy for coronavirus disease 2019 (COVID-19). A thorough understanding of the current body of evidence regarding benefits and risks of this intervention is required.

OBJECTIVES

To assess the effectiveness and safety of convalescent plasma transfusion in the treatment of people with COVID-19; and to maintain the currency of the evidence using a living systematic review approach.

SEARCH METHODS

To identify completed and ongoing studies, we searched the World Health Organization (WHO) COVID-19 Global literature on coronavirus disease Research Database, MEDLINE, Embase, Cochrane COVID-19 Study Register, and the Epistemonikos COVID-19 L*OVE Platform. We searched monthly until 03 March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) evaluating convalescent plasma for COVID-19, irrespective of disease severity, age, gender or ethnicity. We excluded studies that included populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)), as well as studies evaluating standard immunoglobulin.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess bias in included studies we used RoB 2. We used the GRADE approach to rate the certainty of evidence for the following outcomes: all-cause mortality at up to day 28, worsening and improvement of clinical status (for individuals with moderate to severe disease), hospital admission or death, COVID-19 symptoms resolution (for individuals with mild disease), quality of life, grade 3 or 4 adverse events, and serious adverse events.

MAIN RESULTS

In this fourth review update version, we included 33 RCTs with 24,861 participants, of whom 11,432 received convalescent plasma. Of these, nine studies are single-centre studies and 24 are multi-centre studies. Fourteen studies took place in America, eight in Europe, three in South-East Asia, two in Africa, two in western Pacific and three in eastern Mediterranean regions and one in multiple regions. We identified a further 49 ongoing studies evaluating convalescent plasma, and 33 studies reporting as being completed. Individuals with a confirmed diagnosis of COVID-19 and moderate to severe disease 29 RCTs investigated the use of convalescent plasma for 22,728 participants with moderate to severe disease. 23 RCTs with 22,020 participants compared convalescent plasma to placebo or standard care alone, five compared to standard plasma and one compared to human immunoglobulin. We evaluate subgroups on detection of antibodies detection, symptom onset, country income groups and several co-morbidities in the full text. Convalescent plasma versus placebo or standard care alone Convalescent plasma does not reduce all-cause mortality at up to day 28 (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.92 to 1.03; 220 per 1000; 21 RCTs, 19,021 participants; high-certainty evidence). It has little to no impact on need for invasive mechanical ventilation, or death (RR 1.03, 95% CI 0.97 to 1.11; 296 per 1000; 6 RCTs, 14,477 participants; high-certainty evidence) and has no impact on whether participants are discharged from hospital (RR 1.00, 95% CI 0.97 to 1.02; 665 per 1000; 6 RCTs, 12,721 participants; high-certainty evidence). Convalescent plasma may have little to no impact on quality of life (MD 1.00, 95% CI -2.14 to 4.14; 1 RCT, 483 participants; low-certainty evidence). Convalescent plasma may have little to no impact on the risk of grades 3 and 4 adverse events (RR 1.17, 95% CI 0.96 to 1.42; 212 per 1000; 6 RCTs, 2392 participants; low-certainty evidence). It has probably little to no effect on the risk of serious adverse events (RR 1.14, 95% CI 0.91 to 1.44; 135 per 1000; 6 RCTs, 3901 participants; moderate-certainty evidence). Convalescent plasma versus standard plasma We are uncertain whether convalescent plasma reduces or increases all-cause mortality at up to day 28 (RR 0.73, 95% CI 0.45 to 1.19; 129 per 1000; 4 RCTs, 484 participants; very low-certainty evidence). We are uncertain whether convalescent plasma reduces or increases the need for invasive mechanical ventilation, or death (RR 5.59, 95% CI 0.29 to 108.38; 311 per 1000; 1 study, 34 participants; very low-certainty evidence) and whether it reduces or increases the risk of serious adverse events (RR 0.80, 95% CI 0.55 to 1.15; 236 per 1000; 3 RCTs, 327 participants; very low-certainty evidence). We did not identify any study reporting other key outcomes. Convalescent plasma versus human immunoglobulin Convalescent plasma may have little to no effect on all-cause mortality at up to day 28 (RR 1.07, 95% CI 0.76 to 1.50; 464 per 1000; 1 study, 190 participants; low-certainty evidence). We did not identify any study reporting other key outcomes. Individuals with a confirmed diagnosis of SARS-CoV-2 infection and mild disease We identified two RCTs reporting on 536 participants, comparing convalescent plasma to placebo or standard care alone, and two RCTs reporting on 1597 participants with mild disease, comparing convalescent plasma to standard plasma. Convalescent plasma versus placebo or standard care alone We are uncertain whether convalescent plasma reduces all-cause mortality at up to day 28 (odds ratio (OR) 0.36, 95% CI 0.09 to 1.46; 8 per 1000; 2 RCTs, 536 participants; very low-certainty evidence). It may have little to no effect on admission to hospital or death within 28 days (RR 1.05, 95% CI 0.60 to 1.84; 117 per 1000; 1 RCT, 376 participants; low-certainty evidence), on time to COVID-19 symptom resolution (hazard ratio (HR) 1.05, 95% CI 0.85 to 1.30; 483 per 1000; 1 RCT, 376 participants; low-certainty evidence), on the risk of grades 3 and 4 adverse events (RR 1.29, 95% CI 0.75 to 2.19; 144 per 1000; 1 RCT, 376 participants; low-certainty evidence) and the risk of serious adverse events (RR 1.14, 95% CI 0.66 to 1.94; 133 per 1000; 1 RCT, 376 participants; low-certainty evidence). We did not identify any study reporting other key outcomes. Convalescent plasma versus standard plasma We are uncertain whether convalescent plasma reduces all-cause mortality at up to day 28 (OR 0.30, 95% CI 0.05 to 1.75; 2 per 1000; 2 RCTs, 1597 participants; very low-certainty evidence). It probably reduces admission to hospital or death within 28 days (RR 0.49, 95% CI 0.31 to 0.75; 36 per 1000; 2 RCTs, 1595 participants; moderate-certainty evidence). Convalescent plasma may have little to no effect on initial symptom resolution at up to day 28 (RR 1.12, 95% CI 0.98 to 1.27; 1 RCT, 416 participants; low-certainty evidence). We did not identify any study reporting other key outcomes. This is a living systematic review. We search monthly for new evidence and update the review when we identify relevant new evidence.

AUTHORS' CONCLUSIONS

For the comparison of convalescent plasma versus placebo or standard care alone, our certainty in the evidence that convalescent plasma for individuals with moderate to severe disease does not reduce mortality and has little to no impact on clinical improvement or worsening is high. It probably has little to no effect on SAEs. For individuals with mild disease, we have very-low to low certainty evidence for most primary outcomes and moderate certainty for hospital admission or death. There are 49 ongoing studies, and 33 studies reported as complete in a trials registry. Publication of ongoing studies might resolve some of the uncertainties around convalescent plasma therapy for people with asymptomatic or mild disease.

Incorporation of SARS-CoV-2 spike NTD to RBD protein vaccine improves immunity against viral variants

Emerging SARS-CoV-2 variants pose a threat to human health worldwide. SARS-CoV-2 receptor binding domain (RBD)-based vaccines are suitable candidates for booster vaccines, eliciting a focused antibody response enriched for virus neutralizing activity. Although RBD proteins are manufactured easily, and have excellent stability and safety properties, they are poorly immunogenic compared to the full-length spike protein. We have overcome this limitation by engineering a subunit vaccine composed of an RBD tandem dimer fused to the N-terminal domain (NTD) of the spike protein. We found that inclusion of the NTD (1) improved the magnitude and breadth of the T cell and anti-RBD response, and (2) enhanced T follicular helper cell and memory B cell generation, antibody potency, and cross-reactive neutralization activity against multiple SARS-CoV-2 variants, including B.1.1.529 (Omicron BA.1). In summary, our uniquely engineered RBD-NTD-subunit protein vaccine provides a promising booster vaccination strategy capable of protecting against known SARS-CoV-2 variants of concern.

Liver injury in COVID-19 patients with non-alcoholic fatty liver disease: an update

The coronavirus disease 2019 (COVID-19) pandemic has revolutionized the priorities of the medical society worldwide. Although most patients infected with SARS-CoV-2 exhibit respiratory symptoms, other organs may also be involved, including the liver, often resulting in liver injury. Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, and its prevalence is expected to increase together with the epidemics of type 2 diabetes and obesity. Data about liver injury during COVID-19 are numerous, while overviews of this infection in patients with NAFLD, both in terms of respiratory and liver, are emerging. In this review, we summarise the current research focusing on COVID-19 in NAFLD patients and discuss the association between liver injury in COVID-19 subjects and non-alcoholic fatty liver disease.

Convalescent plasma for people with COVID-19: a living systematic review

BACKGROUND

Convalescent plasma may reduce mortality in patients with viral respiratory diseases, and is being investigated as a potential therapy for coronavirus disease 2019 (COVID-19). A thorough understanding of the current body of evidence regarding benefits and risks of this intervention is required.

OBJECTIVES

To assess the effectiveness and safety of convalescent plasma transfusion in the treatment of people with COVID-19; and to maintain the currency of the evidence using a living systematic review approach.

SEARCH METHODS

To identify completed and ongoing studies, we searched the World Health Organization (WHO) COVID-19 Global literature on coronavirus disease Research Database, MEDLINE, Embase, Cochrane COVID-19 Study Register, and the Epistemonikos COVID-19 L*OVE Platform. We searched monthly until 03 March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) evaluating convalescent plasma for COVID-19, irrespective of disease severity, age, gender or ethnicity. We excluded studies that included populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)), as well as studies evaluating standard immunoglobulin.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess bias in included studies we used RoB 2. We used the GRADE approach to rate the certainty of evidence for the following outcomes: all-cause mortality at up to day 28, worsening and improvement of clinical status (for individuals with moderate to severe disease), hospital admission or death, COVID-19 symptoms resolution (for individuals with mild disease), quality of life, grade 3 or 4 adverse events, and serious adverse events.

MAIN RESULTS

In this fourth review update version, we included 33 RCTs with 24,861 participants, of whom 11,432 received convalescent plasma. Of these, nine studies are single-centre studies and 24 are multi-centre studies. Fourteen studies took place in America, eight in Europe, three in South-East Asia, two in Africa, two in western Pacific and three in eastern Mediterranean regions and one in multiple regions. We identified a further 49 ongoing studies evaluating convalescent plasma, and 33 studies reporting as being completed. Individuals with a confirmed diagnosis of COVID-19 and moderate to severe disease 29 RCTs investigated the use of convalescent plasma for 22,728 participants with moderate to severe disease. 23 RCTs with 22,020 participants compared convalescent plasma to placebo or standard care alone, five compared to standard plasma and one compared to human immunoglobulin. We evaluate subgroups on detection of antibodies detection, symptom onset, country income groups and several co-morbidities in the full text. Convalescent plasma versus placebo or standard care alone Convalescent plasma does not reduce all-cause mortality at up to day 28 (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.92 to 1.03; 220 per 1000; 21 RCTs, 19,021 participants; high-certainty evidence). It has little to no impact on need for invasive mechanical ventilation, or death (RR 1.03, 95% CI 0.97 to 1.11; 296 per 1000; 6 RCTs, 14,477 participants; high-certainty evidence) and has no impact on whether participants are discharged from hospital (RR 1.00, 95% CI 0.97 to 1.02; 665 per 1000; 6 RCTs, 12,721 participants; high-certainty evidence). Convalescent plasma may have little to no impact on quality of life (MD 1.00, 95% CI -2.14 to 4.14; 1 RCT, 483 participants; low-certainty evidence). Convalescent plasma may have little to no impact on the risk of grades 3 and 4 adverse events (RR 1.17, 95% CI 0.96 to 1.42; 212 per 1000; 6 RCTs, 2392 participants; low-certainty evidence). It has probably little to no effect on the risk of serious adverse events (RR 1.14, 95% CI 0.91 to 1.44; 135 per 1000; 6 RCTs, 3901 participants; moderate-certainty evidence). Convalescent plasma versus standard plasma We are uncertain whether convalescent plasma reduces or increases all-cause mortality at up to day 28 (RR 0.73, 95% CI 0.45 to 1.19; 129 per 1000; 4 RCTs, 484 participants; very low-certainty evidence). We are uncertain whether convalescent plasma reduces or increases the need for invasive mechanical ventilation, or death (RR 5.59, 95% CI 0.29 to 108.38; 311 per 1000; 1 study, 34 participants; very low-certainty evidence) and whether it reduces or increases the risk of serious adverse events (RR 0.80, 95% CI 0.55 to 1.15; 236 per 1000; 3 RCTs, 327 participants; very low-certainty evidence). We did not identify any study reporting other key outcomes. Convalescent plasma versus human immunoglobulin Convalescent plasma may have little to no effect on all-cause mortality at up to day 28 (RR 1.07, 95% CI 0.76 to 1.50; 464 per 1000; 1 study, 190 participants; low-certainty evidence). We did not identify any study reporting other key outcomes. Individuals with a confirmed diagnosis of SARS-CoV-2 infection and mild disease We identified two RCTs reporting on 536 participants, comparing convalescent plasma to placebo or standard care alone, and two RCTs reporting on 1597 participants with mild disease, comparing convalescent plasma to standard plasma. Convalescent plasma versus placebo or standard care alone We are uncertain whether convalescent plasma reduces all-cause mortality at up to day 28 (odds ratio (OR) 0.36, 95% CI 0.09 to 1.46; 8 per 1000; 2 RCTs, 536 participants; very low-certainty evidence). It may have little to no effect on admission to hospital or death within 28 days (RR 1.05, 95% CI 0.60 to 1.84; 117 per 1000; 1 RCT, 376 participants; low-certainty evidence), on time to COVID-19 symptom resolution (hazard ratio (HR) 1.05, 95% CI 0.85 to 1.30; 483 per 1000; 1 RCT, 376 participants; low-certainty evidence), on the risk of grades 3 and 4 adverse events (RR 1.29, 95% CI 0.75 to 2.19; 144 per 1000; 1 RCT, 376 participants; low-certainty evidence) and the risk of serious adverse events (RR 1.14, 95% CI 0.66 to 1.94; 133 per 1000; 1 RCT, 376 participants; low-certainty evidence). We did not identify any study reporting other key outcomes. Convalescent plasma versus standard plasma We are uncertain whether convalescent plasma reduces all-cause mortality at up to day 28 (OR 0.30, 95% CI 0.05 to 1.75; 2 per 1000; 2 RCTs, 1597 participants; very low-certainty evidence). It probably reduces admission to hospital or death within 28 days (RR 0.49, 95% CI 0.31 to 0.75; 36 per 1000; 2 RCTs, 1595 participants; moderate-certainty evidence). Convalescent plasma may have little to no effect on initial symptom resolution at up to day 28 (RR 1.12, 95% CI 0.98 to 1.27; 1 RCT, 416 participants; low-certainty evidence). We did not identify any study reporting other key outcomes. This is a living systematic review. We search monthly for new evidence and update the review when we identify relevant new evidence.

AUTHORS' CONCLUSIONS

For the comparison of convalescent plasma versus placebo or standard care alone, our certainty in the evidence that convalescent plasma for individuals with moderate to severe disease does not reduce mortality and has little to no impact on clinical improvement or worsening is high. It probably has little to no effect on SAEs. For individuals with mild disease, we have low certainty evidence for our primary outcomes. There are 49 ongoing studies, and 33 studies reported as complete in a trials registry. Publication of ongoing studies might resolve some of the uncertainties around convalescent plasma therapy for people with asymptomatic or mild disease.

Inhalable neutralizing antibodies - promising approach to combating respiratory viral infections

Monoclonal antibodies represent an exciting class of therapeutics against respiratory viral infections. Notwithstanding their specificity and affinity, the conventional parenteral administration is suboptimal in delivering antibodies for neutralizing activity in the airways due to the poor distribution of macromolecules to the respiratory tract. Inhaled therapy is a promising approach to overcome this hurdle in a noninvasive manner, while advances in antibody engineering have led to the development of unique antibody formats which exhibit properties desirable for inhalation. In this Opinion, we examine the major challenges surrounding the development of inhaled antibodies, identify knowledge gaps that need to be addressed and provide strategies from a drug delivery perspective to enhance the efficacy and safety of neutralizing antibodies against respiratory viral infections.

Hyperimmune immunoglobulin for people with COVID-19

BACKGROUND

Hyperimmune immunoglobulin (hIVIG) contains polyclonal antibodies, which can be prepared from large amounts of pooled convalescent plasma or prepared from animal sources through immunisation. They are being investigated as a potential therapy for coronavirus disease 2019 (COVID-19). This review was previously part of a parent review addressing convalescent plasma and hIVIG for people with COVID-19 and was split to address hIVIG and convalescent plasma separately.

OBJECTIVES

To assess the benefits and harms of hIVIG therapy for the treatment of people with COVID-19, and to maintain the currency of the evidence using a living systematic review approach.

SEARCH METHODS

To identify completed and ongoing studies, we searched the World Health Organization (WHO) COVID-19 Research Database, the Cochrane COVID-19 Study Register, the Epistemonikos COVID-19 L*OVE Platform and Medline and Embase from 1 January 2019 onwards. We carried out searches on 31 March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that evaluated hIVIG for COVID-19, irrespective of disease severity, age, gender or ethnicity. We excluded studies that included populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)), as well as studies that evaluated standard immunoglobulin.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess bias in included studies, we used RoB 2. We rated the certainty of evidence, using the GRADE approach, for the following outcomes: all-cause mortality, improvement and worsening of clinical status (for individuals with moderate to severe disease), quality of life, adverse events, and serious adverse events.

MAIN RESULTS

We included five RCTs with 947 participants, of whom 688 received hIVIG prepared from humans, 18 received heterologous swine glyco-humanised polyclonal antibody, and 241 received equine-derived processed and purified F(ab')2 fragments. All participants were hospitalised with moderate-to-severe disease, most participants were not vaccinated (only 12 participants were vaccinated). The studies were conducted before or during the emergence of several SARS-CoV-2 variants of concern. There are no data for people with COVID-19 with no symptoms (asymptomatic) or people with mild COVID-19. We identified a further 10 ongoing studies evaluating hIVIG. Benefits of hIVIG prepared from humans We included data on one RCT (579 participants) that assessed the benefits and harms of hIVIG 0.4 g/kg compared to saline placebo. hIVIG may have little to no impact on all-cause mortality at 28 days (risk ratio (RR) 0.79, 95% confidence interval (CI) 0.43 to 1.44; absolute effect 77 per 1000 with placebo versus 61 per 1000 (33 to 111) with hIVIG; low-certainty evidence). The evidence is very uncertain about the effect on worsening of clinical status at day 7 (RR 0.85, 95% CI 0.58 to 1.23; very low-certainty evidence). It probably has little to no impact on improvement of clinical status on day 28 (RR 1.02, 95% CI 0.97 to 1.08; moderate-certainty evidence). We did not identify any studies that reported quality-of-life outcomes, so we do not know if hIVIG has any impact on quality of life. Harms of hIVIG prepared from humans hIVIG may have little to no impact on adverse events at any grade on day 1 (RR 0.98, 95% CI 0.81 to 1.18; 431 per 1000; 1 study 579 participants; low-certainty evidence). Patients receiving hIVIG probably experience more adverse events at grade 3-4 severity than patients who receive placebo (RR 4.09, 95% CI 1.39 to 12.01; moderate-certainty evidence). hIVIG may have little to no impact on the composite outcome of serious adverse events or death up to day 28 (RR 0.72, 95% CI 0.45 to 1.14; moderate-certainty evidence). We also identified additional results on the benefits and harms of other dose ranges of hIVIG, not included in the summary of findings table, but summarised in additional tables. Benefits of animal-derived polyclonal antibodies We included data on one RCT (241 participants) to assess the benefits and harms of receptor-binding domain-specific polyclonal F(ab´)2 fragments of equine antibodies (EpAbs) compared to saline placebo. EpAbs may reduce all-cause mortality at 28 days (RR 0.60, 95% CI 0.26 to 1.37; absolute effect 114 per 1000 with placebo versus 68 per 1000 (30 to 156) ; low-certainty evidence). EpAbs may reduce worsening of clinical status up to day 28 (RR 0.67, 95% CI 0.38 to 1.18; absolute effect 203 per 1000 with placebo versus 136 per 1000 (77 to 240); low-certainty evidence). It may have some effect on improvement of clinical status on day 28 (RR 1.06, 95% CI 0.96 to 1.17; low-certainty evidence). We did not identify any studies that reported quality-of-life outcomes, so we do not know if EpAbs have any impact on quality of life. Harms of animal-derived polyclonal antibodies EpAbs may have little to no impact on the number of adverse events at any grade up to 28 days (RR 0.99, 95% CI 0.74 to 1.31; low-certainty evidence). Adverse events at grade 3-4 severity were not reported. Individuals receiving EpAbs may experience fewer serious adverse events than patients receiving placebo (RR 0.67, 95% CI 0.38 to 1.19; low-certainty evidence). We also identified additional results on the benefits and harms of other animal-derived polyclonal antibody doses, not included in the summary of findings table, but summarised in additional tables.

AUTHORS' CONCLUSIONS

We included data from five RCTs that evaluated hIVIG compared to standard therapy, with participants with moderate-to-severe disease. As the studies evaluated different preparations (from humans or from various animals) and doses, we could not pool them. hIVIG prepared from humans may have little to no impact on mortality, and clinical improvement and worsening. hIVIG may increase grade 3-4 adverse events. Studies did not evaluate quality of life. RBD-specific polyclonal F(ab´)2 fragments of equine antibodies may reduce mortality and serious adverse events, and may reduce clinical worsening. However, the studies were conducted before or during the emergence of several SARS-CoV-2 variants of concern and prior to widespread vaccine rollout. As no studies evaluated hIVIG for participants with asymptomatic infection or mild disease, benefits for these individuals remains uncertain. This is a living systematic review. We search monthly for new evidence and update the review when we identify relevant new evidence.

A novel heterologous receptor-binding domain dodecamer universal mRNA vaccine against SARS-CoV-2 variants

There are currently approximately 4,000 mutations in the SARS-CoV-2 S protein gene and emerging SARS-CoV-2 variants continue to spread rapidly worldwide. Universal vaccines with high efficacy and safety urgently need to be developed to prevent SARS-CoV-2 variants pandemic. Here, we described a novel self-assembling universal mRNA vaccine containing a heterologous receptor-binding domain (HRBD)-based dodecamer (HRBDdodecamer) against SARS-CoV-2 variants, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (B.1.1.28.1), Delta (B.1.617.2) and Omicron (B.1.1.529). HRBD containing four heterologous RBD (Delta, Beta, Gamma, and Wild-type) can form a stable dodecameric conformation under T4 trimerization tag (Flodon, FD). The HRBDdodecamer -encoding mRNA was then encapsulated into the newly-constructed LNPs consisting of a novel ionizable lipid (4N4T). The obtained universal mRNA vaccine (4N4T-HRBDdodecamer) presented higher efficiency in mRNA transfection and expression than the approved ALC-0315 LNPs, initiating potent immune protection against the immune escape of SARS-CoV-2 caused by evolutionary mutation. These findings demonstrated the first evidence that structure-based antigen design and mRNA delivery carrier optimization may facilitate the development of effective universal mRNA vaccines to tackle SARS-CoV-2 variants pandemic.

Beyond neutralization: Fc-dependent antibody effector functions in SARS-CoV-2 infection

Neutralizing antibodies are known to have a crucial role in protecting against SARS-CoV-2 infection and have been suggested to be a useful correlate of protection for vaccine clinical trials and for population-level surveys. In addition to neutralizing virus directly, antibodies can also engage immune effectors through their Fc domains, including Fc receptor-expressing immune cells and complement. The outcome of these interactions depends on a range of factors, including antibody isotype-Fc receptor combinations, Fc receptor-bearing cell types and antibody post-translational modifications. A growing body of evidence has shown roles for these Fc-dependent antibody effector functions in determining the outcome of SARS-CoV-2 infection. However, measuring these functions is more complicated than assays that measure antibody binding and virus neutralization. Here, we examine recent data illuminating the roles of Fc-dependent antibody effector functions in the context of SARS-CoV-2 infection, and we discuss the implications of these data for the development of next-generation SARS-CoV-2 vaccines and therapeutics.

SARS-CoV-2 vaccines: A double-edged sword throughout rapid evolution of COVID-19

After more than 2 years of the coronavirus disease 2019 pandemic caused by severe acute respiratory syndrome coronavirus 2, several questions have remained unanswered that affected our daily lives. Although substantial vaccine development could resist this challenge, emerging new variants in different countries could be considered as potent concerns regarding the adverse effects of reinfection or postvaccination. Precisely, these concerns address some significant and probable outcomes in vaccinated or reinfected models, followed by some virus challenges, such as antibody-dependent enhancement and cytokine storm. Therefore, the importance of evaluating the effectiveness of neutralizing antibodies (nAbs) elicited by vaccination and the rise of new variants must be addressed.

SARS-CoV-2 infection of phagocytic immune cells and COVID-19 pathology: Antibody-dependent as well as independent cell entry

Our review summarizes the evidence that COVID-19 can be complicated by SARS-CoV-2 infection of immune cells. This evidence is widespread and accumulating at an increasing rate. Research teams from around the world, studying primary and established cell cultures, animal models, and analyzing autopsy material from COVID-19 deceased patients, are seeing the same thing, namely that some immune cells are infected or capable of being infected with the virus. Human cells most vulnerable to infection include both professional phagocytes, such as monocytes, macrophages, and dendritic cells, as well as nonprofessional phagocytes, such as B-cells. Convincing evidence has accumulated to suggest that the virus can infect monocytes and macrophages, while data on infection of dendritic cells and B-cells are still scarce. Viral infection of immune cells can occur directly through cell receptors, but it can also be mediated or enhanced by antibodies through the Fc gamma receptors of phagocytic cells. Antibody-dependent enhancement (ADE) most likely occurs during the primary encounter with the pathogen through the first COVID-19 infection rather than during the second encounter, which is characteristic of ADE caused by other viruses. Highly fucosylated antibodies of vaccinees seems to be incapable of causing ADE, whereas afucosylated antibodies of persons with acute primary infection or convalescents are capable. SARS-CoV-2 entry into immune cells can lead to an abortive infection followed by host cell pyroptosis, and a massive inflammatory cascade. This scenario has the most experimental evidence. Other scenarios are also possible, for which the evidence base is not yet as extensive, namely productive infection of immune cells or trans-infection of other non-immune permissive cells. The chance of a latent infection cannot be ruled out either.

COVID-19-induced liver injury in adult patients: A brief overview

Coronavirus disease has spread worldwide since 2019, causing important pandemic issues and various social health problems to date. Little is known about the origin of this virus and the effects it has on extra-pulmonary organs. The different mechanisms of the virus and the influence it has on humans are still being studied, with hopes of finding a cure for the disease and the pathologies associated with the infection. Liver damage caused by coronavirus disease 2019 (COVID-19) is sometimes underestimated and has been of important clinical interest in the past few years. Hepatic dysfunctions can manifest in different forms which can sometimes be mild and without specific signs and symptoms or be severe with important clinical implications. There are several studies that have tried to explain the mechanism of entry (hepatotropism) of the virus into hepatocytes and the effects the virus has on this important organ. What clearly emerges from the current literature is that hepatic injury represents an important clinical aspect in the management of patients infected with COVID-19, especially in frail patients and those with comorbidities. The aim of our brief overview is to summarize the current literature regarding the forms of hepatic damage, complications, mechanisms of pathology, clinical features of liver injury, influence of comorbidities and clinical management in patients with COVID-19 infection.

The role of IL-6 in coronavirus, especially in COVID-19

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infects both people and animals and may cause significant respiratory problems, including lung illness: Corona Virus Disease 2019 (COVID-19). Swabs taken from the throat and nose of people who have the illness or are suspected of having it have shown this pathogenic virus. When SARS-CoV-2 infects the upper and lower respiratory tracts, it may induce moderate to severe respiratory symptoms, as well as the release of pro-inflammatory cytokines including interleukin 6 (IL-6). COVID-19-induced reduction of IL-6 in an inflammatory state may have a hitherto undiscovered therapeutic impact. Many inflammatory disorders, including viral infections, has been found to be regulated by IL-6. In individuals with COVID-19, one of the primary inflammatory agents that causes inflammatory storm is IL-6. It promotes the inflammatory response of virus infection, including the virus infection caused by SARS-CoV-2, and provides a new diagnostic and therapeutic strategy. In this review article, we highlighted the functions of IL-6 in the coronavirus, especially in COVID-19, showing that IL-6 activation plays an important function in the progression of coronavirus and is a rational therapeutic goal for inflammation aimed at coronavirus.

A self-amplifying RNA vaccine against COVID-19 with long-term room-temperature stability

mRNA vaccines were the first to be authorized for use against SARS-CoV-2 and have since demonstrated high efficacy against serious illness and death. However, limitations in these vaccines have been recognized due to their requirement for cold storage, short durability of protection, and lack of access in low-resource regions. We have developed an easily-manufactured, potent self-amplifying RNA (saRNA) vaccine against SARS-CoV-2 that is stable at room temperature. This saRNA vaccine is formulated with a nanostructured lipid carrier (NLC), providing stability, ease of manufacturing, and protection against degradation. In preclinical studies, this saRNA/NLC vaccine induced strong humoral immunity, as demonstrated by high pseudovirus neutralization titers to the Alpha, Beta, and Delta variants of concern and induction of bone marrow-resident antibody-secreting cells. Robust Th1-biased T-cell responses were also observed after prime or homologous prime-boost in mice. Notably, the saRNA/NLC platform demonstrated thermostability when stored lyophilized at room temperature for at least 6 months and at refrigerated temperatures for at least 10 months. Taken together, this saRNA delivered by NLC represents a potential improvement in RNA technology that could allow wider access to RNA vaccines for the current COVID-19 and future pandemics.

Neutralizing antibodies from the rare convalescent donors elicited antibody-dependent enhancement of SARS-CoV-2 variants infection

Currently, neutralizing antibody and vaccine strategies have been developed by targeting the SARS-CoV-2 strain identified during the early phase of the pandemic. Early studies showed that the ability of SARS-CoV-2 RBD or NTD antibodies to elicit infection enhancement in vivo is still controversial. There are growing concerns that the plasma and neutralizing antibodies from convalescent patients or people receiving vaccines mediate ADE of SARS-CoV-2 variants infections in immune cells. Here, we constructed engineered double-mutant variants containing an RBD mutation and D614G in the spike (S) protein and natural epidemic variants to gain insights into the correlation between the mutations in S proteins and the ADE activities and tested whether convalescent plasma and TOP10 neutralizing antibodies in our laboratory mediated the ADE effects of these SARS-CoV-2 variants. We found that one out of 29 convalescent plasma samples caused the ADE effect of pandemic variant B.1.1.7 and that the ADE effect of wild-type SARS-CoV-2 was not detected for any of these plasma samples. Only one antibody, 55A8, from the same batch of convalescent patients mediated the ADE effects of multiple SARS-CoV-2 variants in vitro, including six double-mutant variants and four epidemic variants, suggesting that ADE activities may be closely related to the antibody itself and the SARS-CoV-2 variants' S proteins. Moreover, the ADE activity of 55A8 depended on FcγRII on immune cells, and the introduction of LALA mutations at the Fc end of 55A8 eliminated the ADE effects in vitro, indicating that 55A8LALA may be a clinical drug used to prevent SARS-CoV-2 variants. Altogether, ADE may occur in rare convalescent patients or vaccinees with ADE-active antibodies who are then exposed to a SARS-CoV-2 variant. These data suggested that potential neutralizing antibodies may need to undergo ADE screening tests for SARS-CoV-2 variants, which should aid in the future design of effective antibody-based therapies.

Does potential antibody-dependent enhancement occur during SARS-CoV-2 infection after natural infection or vaccination? A meta-analysis

Coronavirus disease 2019 (COVID-19) continues to constitute an international public health emergency. Vaccination is a prospective approach to control this pandemic. However, apprehension about the safety of vaccines is a major obstacle to vaccination. Amongst health professionals, one evident concern is the risk of antibody-dependent enhancement (ADE), which may increase the severity of COVID-19. To explore whether ADE occurs in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and increase confidence in the safety of vaccination, we conducted a meta-analysis to investigate the relationship between post-immune infection and disease severity from a population perspective. Databases, including PubMed, EMBASE, Chinese National Knowledge Infrastructure, SinoMed, Scopus, Science Direct, and Cochrane Library, were searched for articles on SARS-CoV-2 reinfection published until 25 October 2021. The papers were reviewed for methodological quality, and a random effects model was used to analyse the results. Heterogeneity was assessed using the I2 statistic. Publication bias was evaluated using a funnel plot and Egger's test. Eleven studies were included in the final meta-analysis. The pooled results indicated that initial infection and vaccination were protective factors against severe COVID-19 during post-immune infection (OR = 0.55, 95%CI = 0.31-0.98). A subgroup (post-immune infection after natural infection or vaccination) analysis showed similar results. Primary SARS-CoV-2 infection and vaccination provide adequate protection against severe clinical symptoms after post-immune infection. This finding demonstrates that SARS-CoV-2 may not trigger ADE at the population level.

SARS-CoV-2 induced hepatic injuries and liver complications

Background

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which is resilient, highly pathogenic, and rapidly transmissible. COVID-19 patients have been reported to have underlying chronic liver abnormalities linked to hepatic dysfunction.

Discussion

Viral RNAs are detectable in fecal samples by RT-PCR even after negative respiratory samples, which suggests that SARS-CoV-2 can affect the gastrointestinal tract and the liver. The case fatality rates are higher among the elderly and those with underlying comorbidities such as hypertension, diabetes, liver abnormality, and heart disease. There is insufficient research on signaling pathways. Identification of molecular mechanisms involved in SARS-CoV-2-induced damages to hepatocytes is challenging. Herein, we demonstrated the multifactorial effects of SARS-CoV-2 on liver injury such as psychological stress, immunopathogenesis, systemic inflammation, ischemia and hypoxia, drug toxicity, antibody-dependent enhancement (ADE) of infection, and several others which can significantly damage the liver.

Conclusion

During the COVID-19 pandemic, it is necessary for clinicians across the globe to pay attention to SARS-CoV-2-mediated liver injury to manage the rising burden of hepatocellular carcinoma. To face the challenges during the resumption of clinical services for patients with pre-existing liver abnormalities and HCC, the impact of SARS-CoV-2 on hepatocytes should be investigated both in vitro and in vivo.

Preclinical study of a DNA vaccine targeting SARS-CoV-2

To fight against the worldwide COVID-19 pandemic, the development of an effective and safe vaccine against SARS-CoV-2 is required. As potential pandemic vaccines, DNA/RNA vaccines, viral vector vaccines and protein-based vaccines have been rapidly developed to prevent pandemic spread worldwide. In this study, we designed plasmid DNA vaccine targeting the SARS-CoV-2 Spike glycoprotein (S protein) as pandemic vaccine, and the humoral, cellular, and functional immune responses were characterized to support proceeding to initial human clinical trials. After intramuscular injection of DNA vaccine encoding S protein with alum adjuvant (three times at 2-week intervals), the humoral immunoreaction, as assessed by anti-S protein or anti-receptor-binding domain (RBD) antibody titers, and the cellular immunoreaction, as assessed by antigen-induced IFNγ expression, were up-regulated. In IgG subclass analysis, IgG2b was induced as the main subclass. Based on these analyses, DNA vaccine with alum adjuvant preferentially induced Th1-type T cell polarization. We confirmed the neutralizing action of DNA vaccine-induced antibodies by a binding assay of RBD recombinant protein with angiotensin-converting enzyme 2 (ACE2), a receptor of SARS-CoV-2, and neutralization assays using pseudo-virus, and live SARS-CoV-2. Further B cell epitope mapping analysis using a peptide array showed that most vaccine-induced antibodies recognized the S2 and RBD subunits. Finally, DNA vaccine protected hamsters from SARS-CoV-2 infection. In conclusion, DNA vaccine targeting the spike glycoprotein of SARS-CoV-2 might be an effective and safe approach to combat the COVID-19 pandemic.

Vaccine-associated enhanced disease in humans and animal models: Lessons and challenges for vaccine development

The fight against infectious diseases calls for the development of safe and effective vaccines that generate long-lasting protective immunity. In a few situations, vaccine-mediated immune responses may have led to exacerbated pathology upon subsequent infection with the pathogen targeted by the vaccine. Such vaccine-associated enhanced disease (VAED) has been reported, or at least suspected, in animal models, and in a few instances in humans, for vaccine candidates against the respiratory syncytial virus (RSV), measles virus (MV), dengue virus (DENV), HIV-1, simian immunodeficiency virus (SIV), feline immunodeficiency virus (FIV), severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1), and the Middle East respiratory syndrome coronavirus (MERS-CoV). Although alleviated by clinical and epidemiological evidence, a number of concerns were also initially raised concerning the short- and long-term safety of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is causing the ongoing COVID-19 pandemic. Although the mechanisms leading to this phenomenon are not yet completely understood, the individual and/or collective role of antibody-dependent enhancement (ADE), complement-dependent enhancement, and cell-dependent enhancement have been highlighted. Here, we review mechanisms that may be associated with the risk of VAED, which are important to take into consideration, both in the assessment of vaccine safety and in finding ways to define models and immunization strategies that can alleviate such concerns.

Antibody-Dependent Enhancement: ″Evil″ Antibodies Favorable for Viral Infections

The pandemics caused by emerging viruses such as severe acute respiratory syndrome coronavirus 2 result in severe disruptions to public health. Vaccines and antibody drugs play essential roles in the control and prevention of emerging infectious diseases. However, in contrast with the neutralizing antibodies (NAbs), sub- or non-NAbs may facilitate the virus to enter the cells and enhance viral infection, which is termed antibody-dependent enhancement (ADE). The ADE of most virus infections is mediated by the Fc receptors (FcRs) expressed on the myeloid cells, while others are developed by other mechanisms, such as complement receptor-mediated ADE. In this review, we comprehensively analyzed the characteristics of the viruses inducing FcRs-mediated ADE and the new molecular mechanisms of ADE involved in the virus entry, immune response, and transcription modulation, which will provide insights into viral pathogenicity and the development of safer vaccines and effective antibody drugs against the emerging viruses inducing ADE.

High viral loads: what drives fatal cases of COVID-19 in vaccinees? - an autopsy study

The rate of SARS-CoV-2 infections in vaccinees has become a relevant serious issue. This study aimed to determine the causes of death, histological organ alteration, and viral spread in relation to demographic, clinical-pathological, viral variants, and vaccine types for deceased individuals with proven SARS-CoV-2 infection after vaccination who died between January and November 2021. Twenty-nine consecutively collected cases were analyzed and compared to 141 nonvaccinated control cases. Autopsies were performed on 16 partially and 13 fully vaccinated individuals. Most patients were elderly and suffered from several relevant comorbidities. Real-time RT-PCR (RT-qPCR) identified a significantly increased rate of generalized viral dissemination within organ systems in vaccinated cases versus nonvaccinated cases (45% vs. 16%, respectively; P = 0.008) mainly with Ct-values of higher than 25 in non-respiratory samples. However, vaccinated cases also showed high viral loads, reaching Ct-values below 10, especially in the upper airways and lungs. This was accompanied by high rates of pulmonal bacterial or mycotic superinfections and the occurrence of immunocompromising factors, such as malignancies, immunosuppressive drug intake, or decreased immunoglobulin levels. All these findings were particularly accentuated in partially vaccinated patients compared to fully vaccinated individuals. The virus dissemination observed in our case study may indicate that patients with an impaired immune system have a decreased ability to eliminate the virus. However, the potential role of antibody-dependent enhancement must also be ruled out in future studies. Fatal cases of COVID-19 in vaccinees were rare and often associated with severe comorbidities or other immunosuppressive conditions.

Liver dysfunction during COVID-19 pandemic: Contributing role of associated factors in disease progression and severity

In December 2019, a new strain of coronavirus was discovered in China, and the World Health Organization declared it a pandemic in March 2020. The majority of people with coronavirus disease 19 (COVID-19) exhibit no or only mild symptoms such as fever, cough, anosmia, and headache. Meanwhile, approximately 15% develop a severe lung infection over the course of 10 d, resulting in respiratory failure, which can lead to multi-organ failure, coagulopathy, and death. Since the beginning of the pandemic, it appears that there has been consideration that pre-existing chronic liver disease may predispose to deprived consequences in conjunction with COVID-19. Furthermore, extensive liver damage has been linked to immune dysfunction and coagulopathy, which leads to a more severe COVID-19 outcome. Besides that, people with COVID-19 frequently have abnormal liver function, with more significant elevations in alanine aminotransferase and aspartate aminotransferase in patients with severe COVID-19 compared to those with mild/moderate disease. This review focuses on the pathogenesis of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in the liver, as well as the use of liver chemistry as a prognostic tool during COVID-19. We also evaluate the findings for viral infection of hepatocytes, and look into the potential mechanisms behind SARS-CoV-2-related liver damage.

IgG targeting distinct seasonal coronavirus- conserved SARS-CoV-2 spike subdomains correlates with differential COVID-19 disease outcomes

Despite SARS-CoV-2 being a "novel" virus, early detection of anti-spike IgG in severe COVID-19 patients may be caused by the amplification of humoral memory responses against seasonal coronaviruses. Here, we examine this phenomenon by characterizing anti-spike IgG responses in non-hospitalized convalescent individuals across a spectrum of COVID-19 severity. We observe that disease severity positively correlates with anti-spike IgG levels, IgG cross-reactivity against other betacoronaviruses (β-CoVs), and FcγR activation. Analysis of IgG targeting β-CoV-conserved and non-conserved immunodominant epitopes within the SARS-CoV-2 spike protein revealed epitope-specific relationships: IgG targeting the conserved heptad repeat (HR) 2 region significantly correlates with milder disease, while targeting the conserved S2'FP region correlates with more severe disease. Furthermore, a lower HR2-to-S2'FP IgG-binding ratio correlates with greater disease severity, with ICU-hospitalized COVID-19 patients showing the lowest HR2/S2'FP ratios. These findings suggest that HR2/S2'FP IgG profiles may predict disease severity and offer insight into protective versus deleterious humoral recall responses.

The Role of Antibodies in the Treatment of SARS-CoV-2 Virus Infection, and Evaluating Their Contribution to Antibody-Dependent Enhancement of Infection

Antibodies play a crucial role in the immune response, in fighting off pathogens as well as helping create strong immunological memory. Antibody-dependent enhancement (ADE) occurs when non-neutralising antibodies recognise and bind to a pathogen, but are unable to prevent infection, and is widely known and is reported as occurring in infection caused by several viruses. This narrative review explores the ADE phenomenon, its occurrence in viral infections and evaluates its role in infection by SARS-CoV-2 virus, which causes coronavirus disease 2019 (COVID-19). As of yet, there is no clear evidence of ADE in SARS-CoV-2, though this area is still subject to further study.

How effective is rescue therapeutic plasma exchange in treatment of SARS-Coronavirus-2?

INTRODUCTION

After the FDA gave emergency approval for the use of therapeutic plasma exchange in treatment for SARS-Coronoavirus-2, we analyzed its efficacy in patients who had failed all other known therapies.

METHODS

This was a prospective observational study of 42 patients with SARS-Coronoavirus-2 who had failed conventional therapy and were treated with therapeutic plasma exchange. Pre- and postexchange clinical and laboratory parameters were monitored. The patients were then also compared with a group of 147 patients with SARS-Coronoavirus-2 who were referred for stage 3 acute renal failure and dialysis from SARS-Coronoavirus-2.

RESULTS

After therapeutic plasma exchange, there were significant improvements in some clinical parameters but mortality remained high; although better than the renal failure group (43.9% vs. 50.7%, p = 0.004).

CONCLUSION

SARS-CoV-2 patients who failed all other therapies had significant mortality with therapeutic plasma exchange; however, their survival was better than SARS-CoV-2 patients with stage 3 acute renal failure.

Humoral, Cellular and Cytokine Immune Responses Against SARS-CoV-2 Variants in COVID-19 Convalescent and Confirmed Patients With Different Disease Severities

Objectives

To assess humoral and cellular immune responses against SARS-CoV-2 variants in COVID-19 convalescent and confirmed patients, to explore the correlation between disease severity, humoral immunity, and cytokines/chemokines in confirmed patients, and to evaluate the ADE risk of SARS-CoV-2.

Methods

Anti-RBD IgG were quantified using an ELISA. Neutralization potency was measured using pseudovirus and real virus. Cellular immunity was measured using ELISpot. Cytokine/chemokine levels were detected using multiplex immunoassays. In vitro ADE assays were performed using Raji cells.

Results

One-month alpha convalescents exhibited spike-specific antibodies and T cells for alpha and delta variants. Notably, the RBD-specific IgG towards the delta variant decreased by 2.5-fold compared to the alpha variant. Besides, serum from individuals recently experienced COVID-19 showed suboptimal neutralizing activity against the delta and omicron variants. Humoral immune response, IL-6, IP-10 and MCP-1 levels were greater in patients with severe disease. Moreover, neither SARS-CoV-1 nor SARS-CoV-2 convalescent sera significantly enhanced SARS-CoV-2 pseudovirus infection.

Conclusions

Significant resistance of the delta and omicron variants to the humoral immune response generated by individuals who recently experienced COVID-19. Furthermore, there was a significant correlation among disease severity, humoral immune response, and specific cytokines/chemokine levels. No evident ADE was observed for SARS-CoV-2.

The role of antigen-presenting cells in the pathogenesis of COVID-19

Coronavirus Disease 2019 (COVID-19) is one of the three lethal coronavirus outbreaks in the recent two decades and a serious threat to global health all over the world. The principal feature of the COVID-19 infection is the so-called "cytokine storm" exaggerated molecular response to virus distribution, which plays massive tissue and organ injury roles. Immunological treatments, including monoclonal antibodies and vaccines, have been suggested as the main approaches in treating and preventing this disease. Therefore, a proper investigation of the roles of antigen-presenting cells (APCs) in the aforementioned immunological responses appears essential. The present review will provide detailed information about APCs' role in the infection and pathogenesis of SARS-CoV-2 and the effect of monoclonal antibodies in diagnosis and treatment.

Passive Immunotherapy Against SARS-CoV-2: From Plasma-Based Therapy to Single Potent Antibodies in the Race to Stay Ahead of the Variants

The COVID-19 pandemic is now approaching 2 years old, with more than 440 million people infected and nearly six million dead worldwide, making it the most significant pandemic since the 1918 influenza pandemic. The severity and significance of SARS-CoV-2 was recognized immediately upon discovery, leading to innumerable companies and institutes designing and generating vaccines and therapeutic antibodies literally as soon as recombinant SARS-CoV-2 spike protein sequence was available. Within months of the pandemic start, several antibodies had been generated, tested, and moved into clinical trials, including Eli Lilly's bamlanivimab and etesevimab, Regeneron's mixture of imdevimab and casirivimab, Vir's sotrovimab, Celltrion's regdanvimab, and Lilly's bebtelovimab. These antibodies all have now received at least Emergency Use Authorizations (EUAs) and some have received full approval in select countries. To date, more than three dozen antibodies or antibody combinations have been forwarded into clinical trials. These antibodies to SARS-CoV-2 all target the receptor-binding domain (RBD), with some blocking the ability of the RBD to bind human ACE2, while others bind core regions of the RBD to modulate spike stability or ability to fuse to host cell membranes. While these antibodies were being discovered and developed, new variants of SARS-CoV-2 have cropped up in real time, altering the antibody landscape on a moving basis. Over the past year, the search has widened to find antibodies capable of neutralizing the wide array of variants that have arisen, including Alpha, Beta, Gamma, Delta, and Omicron. The recent rise and dominance of the Omicron family of variants, including the rather disparate BA.1 and BA.2 variants, demonstrate the need to continue to find new approaches to neutralize the rapidly evolving SARS-CoV-2 virus. This review highlights both convalescent plasma- and polyclonal antibody-based approaches as well as the top approximately 50 antibodies to SARS-CoV-2, their epitopes, their ability to bind to SARS-CoV-2 variants, and how they are delivered. New approaches to antibody constructs, including single domain antibodies, bispecific antibodies, IgA- and IgM-based antibodies, and modified ACE2-Fc fusion proteins, are also described. Finally, antibodies being developed for palliative care of COVID-19 disease, including the ramifications of cytokine release syndrome (CRS) and acute respiratory distress syndrome (ARDS), are described.

Th2-Oriented Immune Serum After SARS-CoV-2 Vaccination Does Not Enhance Infection In Vitro

The relatively lower protection rate of the alum-adjuvanted inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines reminds us of the antibody-dependent enhancement (ADE) phenomenon observed in preclinical studies during the development of vaccines for Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1). In this study, using the S1 segment of the SARS-CoV-2 spike protein or inactivated whole SARS-CoV-2 virus as an antigen and aluminum as an adjuvant, the risk of ADE of infection with T helper 2 (Th2)-oriented immune serum from mice (N=6) and humans (N=5) was examined in immune cell lines, which show different expression patterns of Fc receptors. Neither the immune serum from alum-adjuvanted S1 subunit vaccines nor inactivated SARS-CoV-2 vaccination enhanced SARS-CoV-2 S pseudotyped virus infection in any of the tested cell lines in vitro. Because both of these Th2-oriented immune sera could block SARS-CoV-2 infection without ADE of infection, we speculate that the lower protection rate of the inactivated SARS-CoV-2 vaccine may be attributed to the lower neutralizing antibody titers induced or the pulmonary eosinophilic immunopathology accompanied by eosinophilic infiltration in the lungs upon virus exposure. Adjustment of the immunization schedule to elevate the neutralizing antibody levels and skew adjuvants toward Th1-oriented responses may be considered to increase the efficacies of both inactivated and spike protein-based subunit SARS-CoV-2 vaccines.

Critically Ill Pediatric Patient and SARS-CoV-2 Infection

In December 2019 SARS-CoV-2 initiated a worldwide COVID-19 pandemic, which is still ongoing in 2022. Although adult elderly patients with chronic preexisting diseases had been identified as the most vulnerable group, COVID-19 has also had a significant impact on pediatric intensive care. Early in 2020, a new disease presentation, multisystemic inflammatory syndrome, was described in children. Despite the vaccination that is available for all age categories, due to its selection process, new viral mutations and highly variable vaccination rate, COVID-19 remains a significant clinical challenge in adult and pediatric intensive care in 2022.

Microfluidic Antibody Affinity Profiling Reveals the Role of Memory Reactivation and Cross-Reactivity in the Defense Against SARS-CoV-2

Recent efforts in understanding the course and severity of SARS-CoV-2 infections have highlighted both potentially beneficial and detrimental effects of cross-reactive antibodies derived from memory immunity. Specifically, due to a significant degree of sequence similarity between SARS-CoV-2 and other members of the coronavirus family, memory B-cells that emerged from previous infections with endemic human coronaviruses (HCoVs) could be reactivated upon encountering the newly emerged SARS-CoV-2, thus prompting the production of cross-reactive antibodies. Determining the affinity and concentration of these potentially cross-reactive antibodies to the new SARS-CoV-2 antigens is therefore particularly important when assessing both existing immunity against common HCoVs and adverse effects like antibody-dependent enhancement (ADE) in COVID-19. However, these two fundamental parameters cannot easily be disentangled by surface-based assays like enzyme-linked immunosorbent assays (ELISAs), which are routinely used to assess cross-reactivity. Here, we have used microfluidic antibody affinity profiling (MAAP) to quantitatively evaluate the humoral immune response in COVID-19 convalescent patients by determining both antibody affinity and concentration against spike antigens of SARS-CoV-2 directly in nine convalescent COVID-19 patient and three pre-pandemic sera that were seropositive for common HCoVs. All 12 sera contained low concentrations of high-affinity antibodies against spike antigens of HCoV-NL63 and HCoV-HKU1, indicative of past exposure to these pathogens, while the affinity against the SARS-CoV-2 spike protein was lower. These results suggest that cross-reactivity as a consequence of memory reactivation upon an acute SARS-CoV-2 infection may not be a significant factor in generating immunity against SARS-CoV-2.

SARS-CoV-2 and Influenza Viruses: Strategies to Cope with Co-infection and Bioinformatics Perspective

Almost a century after the devastating pandemic of the Spanish flu, humankind is facing the relatively comparable global outbreak of COVID‐19. COVID‐19 is an infectious disease caused by SARS‐CoV‐2 with an unprecedented transmission pattern. In the face of the recent repercussions of COVID‐19, many have argued that the clinical experience with influenza through the last century may have tremendous implications in the containment of this newly emerged viral disease. During the last 2 years, from the emergence of COVID‐19, tremendous advances have been made in diagnosing and treating coinfections. Several approved vaccines are available now for the primary prevention of COVID‐19 and specific treatments exist to alleviate symptoms. The present review article aims to discuss the pathophysiology, diagnosis, and treatment of SARS‐CoV‐2 and influenza A virus coinfection while delivering a bioinformatics‐based insight into this subject matter.

Therapeutic strategies for COVID-19 patients: An update

The novel coronavirus SARS-coV-2, which emerged in Wuhan in November 2019, has increasingly spread causing a global pandemic that infected more than 444 million people, resulting in severe social and economic ramifications, and claimed more than 6,010,000 lives by March 5, 2022. The pandemic attracted global attention with consequential multiple economic, social, and clinical studies. Among causes of poor clinical outcome of the disease are therapeutic challenges, leading to spirals of studies in search for better therapeutic alternatives. Despite the worsening circumstances of the pandemic, no drug has yet shown remarkable efficacy in the clinical management of COVID-19 patients in large-scale trials. Many potential therapeutic strategies, including the use of nucleotide analogs, chloroquine phosphate, arbidol, protease inhibitors (lopinavir/ritonavir), plasma, monoclonal antibodies, plastic antibodies based on Molecularly Imprinted Polymers (MIPs), traditional Chinese medicine (TCM), nanomaterials, vaccine, and mesenchymal stem cells (MSCs), have emerged with various degrees of successes. Remdesivir and dexamethasone have now been licensed based on the results of randomized controlled trials. Baricitinib, the Janus kinase (JAK) 1/2 inhibitor, is also an attractive candidate due to its properties as a potent anti-inflammatory agent and its hypothesized off-target antiviral effects against SARS-CoV-2. Besides, human plasma from recovered COVID-19 patients is theoretically expected to be safe and effective for both therapy and post-exposure prophylaxis. In light of the literature, the correlation between the reduction of C5aR1/C5aR2 and IL6-IL6R axis, using the available anti-IL6R mAb would be crucial. More, MSCs are a potential therapeutic choice for patients with COVID-19 pneumonia. The coronavirus spike (S) protein that mediates the process of the infection via binding of host cells to the virus receptor is an essential focus for vaccine development. Importantly, with the number of patients increasing daily, there is an urgent need for effective therapeutic intervention. In this review, we expatiated on several strategies deployed for the treatment of COVID-19 infection.

Multisystem inflammatory syndrome in adults (MIS-A) following COVID-19 requiring venoarterial extracorporeal membrane oxygenation

The SARS-CoV-2 virus has caused a global pandemic with serious impact around the world. Patients most commonly present with severe lung involvement and acute respiratory failure; however, multisystem inflammatory syndrome in adults (MIS-A) is a known-although rare-complication. We present a case of a 49-year-old patient who presented with combined cardiogenic and vasodilatory shock and was diagnosed with MIS-A. He initially required venoarterial extracorporeal membrane oxygenation and Impella for haemodynamic support but was able to be weaned off these devices with complete recovery of left ventricular systolic function. This case demonstrates that MIS-A may present as haemodynamic collapse in adults, but complete recovery is possible with proper haemodynamic support.

An engineered bispecific human monoclonal antibody against SARS-CoV-2

The global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic requires effective therapies against coronavirus disease 2019 (COVID-19), and neutralizing antibodies are a promising therapy. A noncompeting pair of human neutralizing antibodies (B38 and H4) blocking SARS-CoV-2 binding to its receptor, ACE2, have been described previously. Here, we develop bsAb15, a bispecific monoclonal antibody (bsAb) based on B38 and H4. bsAb15 has greater neutralizing efficiency than these parental antibodies, results in less selective pressure and retains neutralizing ability to most SARS-CoV-2 variants of concern (with more potent neutralizing activity against the Delta variant). We also selected for escape mutants of the two parental mAbs, a mAb cocktail and bsAb15, demonstrating that bsAb15 can efficiently neutralize all single-mAb escape mutants. Furthermore, prophylactic and therapeutic application of bsAb15 reduced the viral titer in infected nonhuman primates and human ACE2 transgenic mice. Therefore, this bsAb is a feasible and effective strategy to treat and prevent severe COVID-19.