Survey of the current status of subclinical coronavirus disease 2019 (COVID-19)

The Proportion of Long-term Response to Anti-N IgG Antibody after 12 Months for COVID-19 Subclinical Infections and a Longitudinal Survey for COVID-19 Subclinical Infections in 2021

Objective To examine the continuation of antibody prevalence status after 12 months and background factors in antibody-positive subjects following asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods We initially determined the SARS-CoV-2 anti-nucleocapsid protein immunoglobulin G (anti-N IgG) antibody prevalence in 1,603 patients, doctors, and nurses at 65 medical institutions in Kanagawa Prefecture, Japan. We then obtained consent from 33 of the 39 subjects who tested positive and performed follow-up for 12 months. Results Follow-up for up to 12 months showed that a long-term response of the anti-N IgG antibody could be detected in 6 of the 33 participants (18.2%). The proportions with hypertension, using an angiotensin-receptor blocker, and without a drinking habit were higher among the participants with a long-term anti-N IgG antibody response for up to 12 months than among those without a long-term antibody response. Conclusions The proportion of individuals with subclinical COVID-19 who continuously had a positive result for the anti-N IgG antibody at 12 months was low.

Clinical course, viral etiology, and the diagnostic workup for patients with suspected myocarditis: a single-center prospective study

BACKGROUND

Myocarditis is a highly heterogeneous disorder with a challenging diagnostic work-up. We aimed to focus on the possible diagnostic workup for this condition in settings where endomyocardial biopsy as a gold standard is not always feasible, detect the etiologic cardiotropic viruses in our locality, and follow the clinical course in patients admitted with clinically suspected myocarditis.

METHODS

This is a prospective observational study. We recruited patients with clinically suspected myocarditis presenting at a university hospital from October 1st, 2020 until March 31st, 2021. All Patients had a diagnostic coronary angiography and were included only if they had a non-obstructive coronary artery disease. All patients also had cardiac magnetic resonance imaging (CMR) with contrast. Sera were obtained from all suspected patients for detection of antibodies against viruses using enzyme-linked immunosorbent assay, and viral genomes using polymerase chain reaction (PCR), and reverse transcription-PCR. Endomyocardial biopsy was done for patients with a typical CMR picture of myocarditis.

RESULTS

Out of 2163 patients presenting to the hospital within the 6 months, only 51 met the inclusion criteria. Males represented 73%, with a mean age of 39 ± 16 years. CMR showed an ischemic pattern in 4 patients and thus they were excluded. We classified patients into two categories based on CMR results: group A (CMR-positive myocarditis), 12 patients (25.5%), and group B (CMR-negative myocarditis), 35 (74.5%) patients. On serological analysis, 66% of patients (n = 31/47) showed antibodies against the common cardiotropic viruses. Parvovirus B19 IgM in 22 patients (47%) and coxsackievirus IgM in 16 (34%) were the most observed etiologies. Regarding the outcome, 42.5% of patients recovered left ventricular ejection fraction and three patients died at 6 months' clinical follow-up.

CONCLUSION

Patients with Clinically suspected myocarditis represented 2.2% of total hospital admissions in 6 months. CMR is only a good positive test for the diagnosis of acute myocarditis. Parvovirus B19 and coxsackievirus were the most common pathogens in our locality.

TRIAL REGISTRATION

Clinical trial registration no., NCT04312490; first registration: 18/03/2020. First recruited case 01/10/2020. URL: https://register.

CLINICALTRIALS

gov/prs/app/action/SelectProtocol?sid=S0009O3D&selectaction=Edit&uid=U0002DVP&ts=2&cx=9zdfin .

Study on Continuation of Antibody Prevalence Six Months after Detection of Subclinical Severe Acute Respiratory Syndrome Coronavirus 2 Infections

Objective To examine the continuation of antibody prevalence and background factors in antibody-positive subjects after asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods A study was carried out to investigate the SARS-CoV-2 antibody (IgG) prevalence. SARS-CoV-2 antibodies (IgG) were measured and analyzed with immunochromatographic tests. Patients Among 1,603 subjects, comprising patients, physicians, and nurses at 65 medical institutes in Kanagawa, Japan, 39 antibody-positive subjects received follow-up for 6 months. Results Of the 33 subjects who consented to the follow-up (23 patients and 10 medical professionals), continued positivity of IgG antibodies was confirmed in 11 of 32 cases (34.4%) after 2 months, 8 of 33 (24.2%) after 4 months, and 8 of 33 (24.2%) after 6 months. A significant difference was found in the sleeping time, drinking habits, hypertension, and use of angiotensin-receptor blockers on comparing subject background characteristics among three groups: patients with antibody production that continued for six months after the first detection of positivity, patients in whom antibody production stopped at four months, and patients in whom antibody production stopped at two months. Conclusion The continuation rate of IgG antibody prevalence was 24.2% at 6 months after the first detection of antibody positivity in cases with asymptomatic coronavirus disease 2019 (COVID-19) infections. This percentage is low compared with the antibody continuation rate in patients who have recovered from symptomatic COVID-19 infection.

Effect of BCG vaccination against SARS-CoV-2 infection

Based on previous studies, we found that Bacillus Calmette-Guérin(BCG) vaccination may have a role in preventing SARS-CoV-2 infection. Thus, we conducted this meta-analysis to investigate this protective effect. We searched in Embase, PubMed, Web of Science, Cochrane Library, BioRxiv, and MedRxiv databases for studies that evaluated the relationship between BCG vaccination and SARS-CoV-2 infection or COVID-19 disease. The quality of all included studies was assessed through the Risk of Bias in Non-randomized Studies - of Interventions and the Agency for Healthcare Research and Quality. Review Manager (Version 5.3) was used for conducting all data analyses. A total of 8 studies were ultimately included in our meta-analysis. Our primary analysis found significantly lower SARS-CoV-2 infection rate in the BCG vaccination group compared to the control group, with a odds ratio (OR) of 0.61, (95% confidence interval (CI) 0.39 to 0.95, P = 0.03; I² = 31%, and P = 0.21 for heterogeneity). Our study indicated that BCG vaccination can protect against SARS-CoV-2 infection. However, there is insufficient evidence that BCG vaccination can reduce the severity of COVID-19.

A rapid lateral flow immunoassay strip for detection of SARS-CoV-2 antigen using latex microspheres

Background

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a highly infectious and concealed virus that causes pneumonia, severe acute respiratory syndrome, and even death. Although the epidemic has been controlled since the development of vaccines and quarantine measures, many people are still infected, particularly in third‐world countries. Several methods have been developed for detection of SARS‐CoV‐2, but owing to its price and efficiency, the immune strip could be a better method for the third‐world countries.

Methods

In this study, two antibodies were linked to latex microspheres, using 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride and N‐hydroxysuccinimide, as the bridge to decrease the cost further and improve the detection performance. The specificity of the lateral flow immunoassay strip (LFIA) was tested by several common viruses and respiratory bacterial infections. Besides, the reproducibility and stability of the LFIAs were tested on the same batch of test strips. Under optimal conditions, the sensitivity of LFIA was determined by testing different dilutions of the positive specimens.

Results

The proposed LFIAs were highly specific, and the limit of detection was as low as 25 ng/mL for SARS‐CoV‐2 antigens. The clinical applicability was evaluated with 659 samples (230 positive and 429 negative samples) by using both LFIA and rRT‐PCR. Youden’s index (J) was used to assess the performance of these diagnostic tests. The sensitivity and specificity were 98.22% and 97.93%, respectively, and J is 0.9615. The sensitivity and specificity were 98.22% and 97.93%, respectively, and J is 0.9615. In addition, the consistency of our proposed LFIA was analyzed using Cohen's kappa coefficient (κ = 0.9620).

Conclusion

We found disease stage, age, gender, and clinical manifestations have only a slight influence on the diagnosis. Therefore, the lateral flow immunoassay SARS‐CoV‐2 antigen test strip is suitable for point‐of‐care detection and provides a great application for SARS‐CoV‐2 epidemic control in the third‐world countries.

COVID-19 Subclinical Infection and Immunity: A Review

The aetiologic agent of COVID-19 is a novel coronavirus, SARS-CoV-2. Like other coronaviruses, it generally induces enteric and respiratory diseases in animals and humans. COVID-19 may be subclinical, and symptomatic, ranging from mild-to-severe disease. The spectrum of presentation is the result of several factors ranging from the inoculum size, inherent host susceptibility, possible cross-reacting circulating antibodies. Subclinical viral infections are associated with widespread community transmission and in some cases like Polio, herd immunity. An understanding of the biology and immune behavior in subclinical coronavirus disease 2019 (COVID-19) might be useful in the quest for vaccine development as well as the current control efforts against the COVID-19 pandemic. We carried out a narrative review of the available literature on the biology, etiopathogenesis, clinical manifestation of SARS-CoV-2 viral infection, focusing on our current understanding of the disease mechanisms and its clinical manifestation, and the host immune response to the infection. We also highlighted some of the research gaps regarding subclinical infection in COVID-19 and its potential application for vaccine development and other preventive efforts toward containing the current COVID-19 pandemic.

Prevalence of SARS-CoV-2 antibodies among nurses: A systematic review and meta-analysis

Aims and Objectives

This systematic review and meta‐analysis reports the seroprevalence of SARS‐CoV‐2 antibodies among nurses.

Background

With a growing body of literature reporting the positive serology for SARS‐CoV‐2 antibodies among healthcare workers, it remains unclear whether staff at the point of direct patient care are more prone to developing and transmitting the virus. Given nurses make up the majority of the global health workforce, outbreaks among these workers could severely undermine a health system’s capability to manage the pandemic. We aimed to summarise and report the seroprevalence of SARS‐CoV‐2 antibodies among nurses globally.

Design

Systematic review and meta‐analyses.

Methods

This systematic review was developed, undertaken and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guideline. We searched the electronic medical literature databases: MEDLINE; CINAHL; and EMBASE for studies reporting the seroprevalence of SARS‐CoV‐2 antibodies among nursing staff. Studies that reported nursing specific data were included in this review. Study quality was evaluated using the Joanna Briggs Institute checklist for studies reporting prevalence data. Studies were stratified according to the World Health Organisation region classifications, and results were presented using forest plots and summary prevalence and variance was estimated using a random effects model.

Results

Our electronic search identified 1687 potential studies, of which 1148 were screened for eligibility after duplicates were removed, and 51 of the studies were included in our meta‐analysis. The overall seroprevalence of SARS‐CoV‐2 antibodies among nurses was estimated to be 8.1% (95% CI 6.9%–9.4%) among the 60,571 participants included in the studies. Seropositivity was highest in the African region (48.2%, 95% CI 39.2%–57.3%), followed by the European region (10.3%, 95% CI 8.0%–12.5%), the Region of the Americas (8.4%, 95% CI 6.0%–10.7%), the South‐East Asia region (3.0%, 95% CI 0.00%–6.5%) and the Western Pacific region (0.5%, 95% CI 0.0%–1.0%). Pooled estimates were unable to be calculated in the Eastern Mediterranean region due to insufficient studies.

Conclusion

The seroprevalence of SARS‐CoV‐2 antibodies among nurses is comparable to other healthcare workers, and possibly similar to the general population. Early adoption and adherence to personal protective equipment and social distancing measures could explain these similarities, meaning the majority of staff contracted the virus through community transmission and not in a healthcare setting.

Relevance to clinical practice

Fear and uncertainty have been features of this pandemic, including among nurses. This meta‐analysis should provide some comfort to nurses that risks are similar to community exposure when adequate PPE is available and there is an adherence to infection control measures.

Evaluation of a new point-of-care quantitative reverse transcription polymerase chain test for detecting severe acute respiratory syndrome coronavirus 2

Background

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection is rapidly spreading worldwide, and the resultant disease, coronavirus disease (COVID‐19), has become a global pandemic. Although there are multiple methods for detecting SARS‐CoV‐2, there are some issues with such tests, including long processing time, expense, low sensitivity, complexity, risk of contamination, and user friendly. This study evaluated the reproducibility and usability of a new point‐of‐care test (POCT) using real‐time quantitative reverse transcription polymerase chain reaction (qRT‐PCR) for detecting SARS‐CoV‐2.

Methods

Samples from 96 patients with suspected SARS‐CoV‐2 infection were assessed using the real‐time qRT‐PCR‐based POCT and the conventional real‐time qRT‐PCR method based on the Japanese National Institute of Infectious Diseases guidelines (registration number: jRCT1032200025).

Results

The real‐time qRT‐PCR‐based POCT had a positive agreement rate of 90.0% (18/20), a negative agreement rate of 100% (76/76), and a total agreement rate of 97.9% (94/96), and the significantly high score of questionnaire survey (total score p < 0.0001). In the two cases in which real‐time qRT‐PCR‐based POCT results did not match conventional real‐time qRT‐PCR test results, the SARS‐CoV‐2 RNA copy numbers were 8.0 copies per test in one case and below the detection limit in the other case when quantified using conventional real‐time qRT‐PCR. All patients could be triaged within 1 day using the real‐time qRT‐PCR‐based POCT without invalid reports.

Conclusions

The real‐time qRT‐PCR‐based POCT not only had high reproducibility and useability but also allowed rapid patient triage. Therefore, it may be helpful in clinical settings.

Retrospective of International Serological Studies on the Formation and Dynamics of the Humoral Immune Response to SARS-CoV-2: from 2020 to 2021

Last year the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has started. The new coronavirus is highly contagious and causes severe complications. The mechanisms of humoral immunity and kinetics of SARS-CoV-2 specific antibodies in a population are not well understood. Therefore, we aimed to summarize and analyze numerous global and Russian serological studies for understanding dynamics of the SARSCoV-2 humoral immune response and getting an accurate picture of the seroprevalence to SARS-CoV-2 in the world population. The PubMed and e-library databases were searched from February 2020 to March 2021 using terms “SARSCoV-2”, “antibodies”, “humoral immunity”. At the beginning of the pandemic first studies were cross-sectional by design and were responsible for determination of the seropositivity and for understanding the fundamental humoral immunity parameters of SARS-CoV-2. Since then, longitudinal seroepidemiological studies have been studying antibody kinetics. Seroconversion time for IgM, IgG antibodies varies, but most researchers report the seroconversion of IgM from the 1st to 14th days after the onset of clinical manifestations, and the seroconversion for IgG is around the 14th day with a concentration peak by the 21st day. Regarding seroprevalence we may say about low herd immunity at the COVID-19 pandemic. Thus, global seroprevalence is about 10 %, and more than 20 % for regions with high incidence and among healthcare workers. Seroprevalence studies have to be continued for more accurate monitoring of long-term humoral immunity to SARS-CoV-2, because the majority of the world’s population is still susceptible to SARS-CoV-2 infection. 

Easy Synthesis of Complex Biomolecular Assemblies: Wheat Germ Cell-Free Protein Expression in Structural Biology

Cell-free protein synthesis (CFPS) systems are gaining more importance as universal tools for basic research, applied sciences, and product development with new technologies emerging for their application. Huge progress was made in the field of synthetic biology using CFPS to develop new proteins for technical applications and therapy. Out of the available CFPS systems, wheat germ cell-free protein synthesis (WG-CFPS) merges the highest yields with the use of a eukaryotic ribosome, making it an excellent approach for the synthesis of complex eukaryotic proteins including, for example, protein complexes and membrane proteins. Separating the translation reaction from other cellular processes, CFPS offers a flexible means to adapt translation reactions to protein needs. There is a large demand for such potent, easy-to-use, rapid protein expression systems, which are optimally serving protein requirements to drive biochemical and structural biology research. We summarize here a general workflow for a wheat germ system providing examples from the literature, as well as applications used for our own studies in structural biology. With this review, we want to highlight the tremendous potential of the rapidly evolving and highly versatile CFPS systems, making them more widely used as common tools to recombinantly prepare particularly challenging recombinant eukaryotic proteins.

Development of a cell-free protein synthesis system for practical use

Conventional cell-free protein synthesis systems had been the major platform to study the mechanism behind translating genetic information into proteins, as proven in the central dogma of molecular biology. Albeit being powerful research tools, most of the in vitro methods at the time failed to produce enough protein for practical use. Tremendous efforts were being made to overcome the limitations of in vitro translation systems, though mostly with limited success. While great knowledge was accumulated on the translation mechanism and ribosome structure, researchers rationalized that it may be impossible to fully reconstitute such a complex molecular process in a test tube. This review will examine how we have solved the difficulties holding back progress. Our newly developed cell-free protein synthesis system is based on wheat embryos and has many excellent characteristics, in addition to its high translation activity and robustness. Combined with other novel elementary technologies, we have established cell-free protein synthesis systems for practical use in research and applied sciences.