SARS-CoV-2 Detection in Fecal Sample from a Patient with Typical Findings of COVID-19 Pneumonia on CT but Negative to Multiple SARS-CoV-2 RT-PCR Tests on Oropharyngeal and Nasopharyngeal Swab Samples

The first report on detecting SARS-CoV-2 inside bacteria of the human gut microbiome: A case series on asymptomatic family members and a child with COVID-19

Many studies report the importance of using feces as source sample for detecting SARS-CoV-2 in patients with COVID-19 symptoms but who are negative to oropharyngeal/ nasopharyngeal tests. Here, we report the case of an asymptomatic child whose family members had negative results with the rapid antigen nasopharyngeal swab tests. The 21-month-old child presented with fever, diarrhea, bilateral conjunctivitis, and conspicuous lacrimation. In this study, analysis for the presence of SARS-CoV-2 in fecal samples by using Luminex technology allowed accurate detection of the presence of the viral RNA in the feces of the child and of all her relatives, which thus resulted to be positive but asymptomatic. It is the first time that SARS-CoV-2- is observed inside the bacteria of the human gut microbiome and outside a matrix resembling extracellular bacterial lysates, in agreement with a bacteriophage mechanism with the images obtained by transmission electron microscopy (TEM), post-embedding immunogold, and by fluorescence microscope. In addition to the typical observations of respiratory symptoms, accurate evaluation of clinical gastrointestinal and neurological symptoms, combined with efficient highly sensitive molecular testing on feces, represent an efficient approach for detecting SARS-CoV-2, and for providing the correct therapy in challenging COVID-19 cases, like the one here reported.

Development and characterization of a multimeric recombinant protein using the spike protein receptor binding domain as an antigen to induce SARS-CoV-2 neutralization

BACKGROUND

SARS-CoV2 virus, responsible for the COVID-19 pandemic, has four structural proteins and 16 nonstructural proteins. S-protein is one of the structural proteins exposed on the virus surface and is the main target for producing neutralizing antibodies and vaccines. The S-protein forms a trimer that can bind the angiotensin-converting enzyme 2 (ACE2) through its receptor binding domain (RBD) for cell entry.

AIMS

The goal of this study was to express in HEK293 cells a new RBD recombinant protein in a constitutive and stable manner in order to use it as an alternative immunogen and diagnostic tool for COVID-19.

MATERIALS & METHODS

The protein was designed to contain an immunoglobulin signal sequence, an explanded C-terminal section of the RBD, a region responsible for the bacteriophage T4 trimerization inducer, and six histidines in the pCDNA-3.1 plasmid. Following transformation, the cells were selected with geneticin-G418 and purified from serum-fre culture supernatants using Ni2+-agarand size exclusion chromatography. The protein was structurally identified by cross-linking and circular dichroism experiments, and utilized to immunize mice in conjuction with AS03 or alum adjuvants. The mice sera were examined for antibody recognition, receptor-binding inhibition, and virus neutralization, while spleens were evaluated for γ-interferon production in the presence of RBD.

RESULTS

The protein released in the culture supernatant of cells, and exhibited a molecular mass of 135 kDa with a secondary structure like the monomeric and trimeric RBD. After purification, it formed a multimeric structure comprising trimers and hexamers, which were able to bind the ACE2 receptor. It generated high antibody titers in mice when combined with AS03 adjuvant (up to 1:50,000). The sera were capable of inhibiting binding of biotin-labeled ACE2 to the virus S1 subunit and could neutralize the entry of the Wuhan virus strain into cells at dilutions up to 1:2000. It produced specific IFN-γ producing cells in immunized mouse splenocytes.

DISCUSSION

Our data describe a new RBD containing protein, forming trimers and hexamers, which are able to induce a protective humoral and cellular response against SARS-CoV2.

CONCLUSION

These results add a new arsenal to combat COVID-19, as an alternative immunogen or antigen for diagnosis.

Dry eye symptoms are prevalent in moderate-severe COVID-19, while SARS-COV-2 presence is higher in mild COVID-19: Possible ocular transmission risk of COVID-19

Purpose

To evaluate the correlation between dry eye symptoms and coronavirus disease 2019 (COVID-19) infection and to assess the real-time reverse transcription-polymerase chain reaction (RT‒PCR) of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) from the conjunctival swab.

Methods

A prospective observational case series study was conducted of all suspected and confirmed COVID-19 patients from Dr. Cipto Mangunkusumo Hospital (RSCM) and the Universitas Indonesia Hospital (RSUI). On the first day of the visit (day 0), systemic clinical symptoms and naso-oropharyngeal (NO) RT‒PCR results will classify all subjects as non-, suspected, or confirmed (mild, moderate, and severe) COVID-19. In all patients, we determined the dry eye symptoms based on the Ocular Surface Disease Index (OSDI) and followed up 7(day 7) and 14 days (day 14) after the first visit. When it was technically possible, we also examined the objective dry eye measurements: tear meniscus height (TMH), noninvasive Keratograph® break-up time (NIKBUT), and ocular redness. Additionally, we took conjunctival swab samples for SARS-CoV-2 RT-PCR in all patients.

Results

The OSDI scores for 157 patients decreased across days 0, 7, and 14 (median (interquartile range): 2.3 (0-8), 0 (0-3), and 0 (0-0), p value < 0.0001 (D0 vs D14). The moderate-severe COVID-19 group had a higher OSDI score than the other groups at median D0 (15.6 vs 0-2.3), p value < 0.0001 and this pattern was consistently seen at follow-up D7 and D14. However, dry eye complaints were not correlated with the three objective dry eye measurements in mild-moderate COVID-19 patients. NO RT‒PCR results were positive in 32 (20.4%) patients, namely, 13 and 19 moderate-severe and mild COVID-19 patients, respectively. Positive RT‒PCR results were observed in 7/157 (4.5%) conjunctival swab samples from 1 in non-COVID-19 group and 6 in mild group.

Conclusion

In the early phase of infection, COVID-19 patients experience dry eye symptoms, which have no correlation with objective dry eye measurements. SARS-CoV-2 in conjunctival swab samples can be detected in patients with normal-to-mild COVID-19, which shows the risk of ocular transmission.

A retrospective cohort study on early antibiotic use in vaccinated and unvaccinated COVID-19 patients

The bacteriophage behavior of SARS-CoV-2 during the acute and post-COVID-19 phases appears to be an important factor in the development of the disease. The early use of antibiotics seems to be crucial to inhibit disease progression-to prevent viral replication in the gut microbiome, and control toxicological production from the human microbiome. To study the impact of specific antibiotics on recovery from COVID-19 and long COVID (LC) taking into account: vaccination status, comorbidities, SARS-CoV-2 wave, time of initiation of antibiotic therapy and concomitant use of corticosteroids and nonsteroidal anti-inflammatory drugs (NSAIDs). A total of 211 COVID-19 patients were included in the study: of which 59 were vaccinated with mRNA vaccines against SARS-CoV-2 while 152 were unvaccinated. Patients were enrolled in three waves: from September 2020 to October 2022, corresponding to the emergence of the pre-Delta, Delta, and Omicron variants of the SARS-CoV-2 virus. The three criteria for enrolling patients were: oropharyngeal swab positivity or fecal findings; moderate symptoms with antibiotic intake; and measurement of blood oxygen saturation during the period of illness. The use of antibiotic combinations, such as amoxicillin with clavulanic acid (875 + 125 mg tablets, every 12 h) plus rifaximin (400 mg tablets every 12 h), as first choice, as suggested from the previous data, or azithromycin (500 mg tablets every 24 h), plus rifaximin as above, allows healthcare professionals to focus on the gut microbiome and its implications in COVID-19 disease during patient care. The primary outcome measured in this study was the estimated average treatment effect, which quantified the difference in mean recovery between patients receiving antibiotics and those not receiving antibiotics at 3 and 9 days after the start of treatment. In the analysis, both vaccinated and unvaccinated groups had a median illness duration of 7 days (interquartile range [IQR] 6-9 days for each; recovery crude hazard ratio [HR] = 0.94, p = 0.700). The median illness duration for the pre-Delta and Delta waves was 8 days (IQR 7-10 days), while it was shorter, 6.5 days, for Omicron (IQR 6-8 days; recovery crude HR = 1.71, p < 0.001). These results were confirmed by multivariate analysis. Patients with comorbidities had a significantly longer disease duration: median 8 days (IQR 7-10 days) compared to 7 days (IQR 6-8 days) for those without comorbidities (crude HR = 0.75, p = 0.038), but this result was not confirmed in multivariate analysis as statistical significance was lost. Early initiation of antibiotic therapy resulted in a significantly shorter recovery time (crude HR = 4.74, p < 0.001). Concomitant use of NSAIDs did not reduce disease duration and in multivariate analysis prolonged the disease (p = 0.041). A subgroup of 42 patients receiving corticosteroids for a median of 3 days (IQR 3-6 days) had a longer recovery time (median 9 days, IQR 8-10 days) compared to others (median 7 days, IQR 6-8 days; crude HR = 0.542, p < 0.001), as confirmed also by the adjusted HR. In this study, a statistically significant reduction in recovery time was observed among patients who received early antibiotic treatment. Early initiation of antibiotics played a crucial role in maintaining higher levels of blood oxygen saturation. In addition, it is worth noting that a significant number of patients who received antibiotics in the first 3 days and for a duration of 7 days, during the acute phase did not develop LC.

Detection of recombinant Spike protein in the blood of individuals vaccinated against SARS-CoV-2: Possible molecular mechanisms

PURPOSE

The SARS-CoV-2 pandemic prompted the development and use of next-generation vaccines. Among these, mRNA-based vaccines consist of injectable solutions of mRNA encoding for a recombinant Spike, which is distinguishable from the wild-type protein due to specific amino acid variations introduced to maintain the protein in a prefused state. This work presents a proteomic approach to reveal the presence of recombinant Spike protein in vaccinated subjects regardless of antibody titer.

EXPERIMENTAL DESIGN

Mass spectrometry examination of biological samples was used to detect the presence of specific fragments of recombinant Spike protein in subjects who received mRNA-based vaccines.

RESULTS

The specific PP-Spike fragment was found in 50% of the biological samples analyzed, and its presence was independent of the SARS-CoV-2 IgG antibody titer. The minimum and maximum time at which PP-Spike was detected after vaccination was 69 and 187 days, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The presented method allows to evaluate the half-life of the Spike protein molecule "PP" and to consider the risks or benefits in continuing to administer additional booster doses of the SARS-CoV-2 mRNA vaccine. This approach is of valuable support to complement antibody level monitoring and represents the first proteomic detection of recombinant Spike in vaccinated subjects.

Epidemiology and analysis of SARS-CoV-2 Omicron subvariants BA.1 and 2 in Taiwan

The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), first detected in October 2021, possessed many mutations compared to previous variants. We aimed to identify and analyze SARS-CoV-2 Omicron subvariants among coronavirus disease 2019 (COVID-19) patients between January 2022 and September 2022 in Taiwan. The results revealed that BA.2.3.7, featuring K97E and G1251V in the spike protein compared with BA.2, emerged in March 2022 and persistently dominated between April 2022 and August 2022, resulting in the largest COVID-19 outbreak since 2020. The accumulation of amino acid (AA) variations, mainly AA substitution, in the spike protein was accompanied by increasing severity in Omicron-related COVID-19 between April 2022 and January 2023. Older patients were more likely to have severe COVID-19, and comorbidity was a risk factor for COVID-19-related mortality. The accumulated case fatality rate (CFR) dropped drastically after Omicron variants, mainly BA.2.3.7, entered Taiwan after April 2022, and the CFR was 0.16% in Taiwan, which was lower than that worldwide (0.31%) between April 2021 and January 2023. The relatively low CFR in Omicron-related COVID-19 patients can be attributed to adjustments to public health policies, promotion of vaccination programs, effective antiviral drugs, and the lower severity of the Omicron variant.

COVID-19, Obesity, and GRP78: Unraveling the Pathological Link

The coronavirus disease 2019 (COVID-19) pandemic, driven by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to an unprecedented global surge in infections and fatalities. Notably, obesity has emerged as an important susceptibility factor for COVID-19; however, the pathological mechanisms for this remain poorly understood. Recent studies proposed a role for glucose-regulated protein 78 (GRP78), a protein implicated in both obesity and metabolic syndrome, which may function as a binding partner and/or co-receptor for SARS-CoV-2. Given its crucial involvement in diverse biological processes, GRP78 likely plays a major role in multiple facets of the viral life cycle and the pathology of COVID-19. This perspective review discusses the potential contributions of GRP78 to the dynamics of SARS-CoV-2 infection and pathology, particularly in the context of obesity. The primary objective is to facilitate a deeper understanding of the pathogenesis of COVID-19. Through this exploration, we aim to illuminate the complex interactions underpinning the nexus of COVID-19, obesity, and GRP78, ultimately paving the way for informed therapeutic strategies and preventive measures.

SARS-CoV-2 Burden in Wastewater and its Elimination Using Disinfection

Background

Pathogenic viruses have been abundant and diverse in wastewater, reflecting the pattern of infection in humans. Human feces, urine, and perhaps other washouts that frequently circulate in sewage systems may contaminate wastewater with SARS-CoV-2. It's crucial to effectively disinfect wastewater since poorly handled wastewater could put the population at risk of infection.

Aims

To emphasize the presence and spread of SARS-CoV-2 in sewage (wastewater) through viral shedding from the patients to detect the virus in the population using wastewater-based epidemiology. Also, to effectively manage the transmission of SARS-CoV-2 and reduce the spread of the virus in the population using disinfectants is highlighted.

Methods

We evaluated articles from December 2019 to August 2022 that addressed SARS-CoV-2 shedding in wastewater and surveillance through wastewater-based epidemiology. We included the papers on wastewater disinfection for the elimination of SARS-CoV-2. Google Scholar, PubMed, and Research4Life are the three electronic databases from which all of the papers were retrieved.

Results

It is possible for viral shedding to get into the wastewater. The enumeration of viral RNA from it can be used to monitor virus circulation in the human community. SARS-CoV-2 can be removed from wastewater by using modern disinfection techniques such as sodium hypochlorite, liquid chlorine, chlorine dioxide, peracetic acid, and ultraviolet light.

Conclusion

SARS-CoV-2 burden estimates at the population level can be obtained via longitudinal examination of wastewater, and SARS-CoV-2 can be removed from the wastewater through disinfection.

Comparative analysis of SARS-CoV-2 detection methods using stool, blood, and nasopharyngeal swab samples

Introduction

as a public health policy, the ongoing global coronavirus disease 2019 vaccination drives require continuous tracking, tracing, and testing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Diagnostic testing is important in virus detection and understanding its spread for timely intervention. This is especially important for low-income settings where the majority of the population remains untested. This is well supported by the fact that of about 9% of the Kenyan population had been tested for the virus.

Methods

this was a cross-sectional study conducted at the Kisumu and Siaya Referral Hospitals in Kenya. Here we report on the sensitivity and specificity of the rapid antigen detection test (Ag-RDT) of SARS-CoV-2 compared with the quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) using stool and nasopharyngeal swab samples. Further, the mean Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibody levels among symptomatic and asymptomatic individuals in western Kenya were evaluated.

Results

the sensitivity and specificity of Ag-RDT were 76.3% (95% CI, 59.8-88.6%) and 96.3% (95% CI, 87.3-99.5%) with a negative and positive predictive value of 85% (95% CI, 73.8%-93.0%) and 93% (95% CI, 78.6%-99.2%) respectively. There was substantial agreement of 88% (Kappa value of 0.75, 95% CI, 0.74-0.77) between Ag-RDT and nasopharyngeal swab RT-qPCR, and between stool and nasopharyngeal swab RT-qPCR results (83.7% agreement, Kapa value 0.62, 95% CI 0.45-0.80). The mean IgM and IgG antibody response to SARS-CoV-2 were not different in asymptomatic individuals, 1.11 (95% CI, 0.78-1.44) and 0.88 (95% CI, 0.65-1.11) compared to symptomatic individuals 4.30 (95% CI 3.30-5.31) and 4.16 (95% CI 3.32 -5.00).

Conclusion

the choice of an appropriate SARS-CoV-2 diagnostic, screening, and surveillance test should be guided by the specific study needs and a rational approach for optimal results.

A Pictorial Essay Describing the CT Imaging Features of COVID-19 Cases throughout the Pandemic with a Special Focus on Lung Manifestations and Extrapulmonary Vascular Abdominal Complications

With the Omicron wave, SARS-CoV-2 infections improved, with less lung involvement and few cases of severe manifestations. In this pictorial review, there is a summary of the pathogenesis with particular focus on the interaction of the immune system and gut and lung axis in both pulmonary and extrapulmonary manifestations of COVID-19 and the computed tomography (CT) imaging features of COVID-19 pneumonia from the beginning of the pandemic, describing the typical features of COVID-19 pneumonia following the Delta variant and the atypical features appearing during the Omicron wave. There is also an outline of the typical features of COVID-19 pneumonia in cases of breakthrough infection, including secondary lung complications such as acute respiratory distress disease (ARDS), pneumomediastinum, pneumothorax, and lung pulmonary thromboembolism, which were more frequent during the first waves of the pandemic. Finally, there is a description of vascular extrapulmonary complications, including both ischemic and hemorrhagic abdominal complications.

Effect of SARS-CoV-2 Infection and COVID-19 Vaccination on Oxidative Status of Human Placenta: A Preliminary Study

Infection with SARS-CoV-2 during pregnancy increases the risk of pregnancy complications associated with inflammation, which could lead to oxidative stress in the placenta. Whether vaccination against COVID-19 has any effect is unclear. This study aimed to analyze the effects of SARS-CoV-2 infection and vaccination against COVID-19 during pregnancy on oxidative stress in the placenta and on extracellular DNA (ecDNA) in umbilical cord plasma. Placenta samples from healthy uninfected and unvaccinated control patients who recovered from COVID-19 and women vaccinated against COVID-19 during pregnancy were collected. Biomarkers of oxidative damage and antioxidant capacity were assessed in the placenta homogenates. EcDNA and deoxyribonuclease activity were quantified in umbilical cord plasma using real-time PCR and the single radial enzyme diffusion method, respectively. Markers of oxidative damage to lipids and proteins as well as antioxidant capacity in the placenta did not differ between the study groups. No differences were observed in total, nuclear or mitochondrial ecDNA, or deoxyribonuclease activity in the umbilical cord plasma. Taking into account the limits of a small observational study, our results suggest that the infection with SARS-CoV-2 and vaccination against COVID-19 do not induce any major disturbances in the balance between the production of free radicals and antioxidant activity in the placenta. This is in line with the minor effects on fetal outcomes and ecDNA as a suggested marker of fetal well-being.

A comprehensive overview on the transmission, pathogenesis, diagnosis, treatment, and prevention of SARS-CoV-2

Severe acute respiratory syndrome coronavirus (SARS-CoV) is a single positive-strand RNA virus that is responsible for the current pandemic that the world has been facing since 2019. The primary route of transmission of SARS-CoV-2 is through respiratory tract transmission. However, other transmission routes such as fecal-oral, vertical transmission, and aerosol-eye also exist. In addition, it has been found that the pathogenesis of this virus involves the binding of the virus's S protein to its host cell surface receptor angiotensin-converting enzyme 2, which results in the subsequent membrane fusion that is required for SARS-CoV-2 to replicate and complete its entire life. The clinical symptoms of patients infected with SARS-CoV-2 can range from asymptomatic to severe. The most common symptoms seen include fever, dry cough, and fatigue. Once these symptoms are observed, a nucleic acid test is done using reverse transcription-polymerase chain reaction. This currently serves as the main confirmatory tool for COVID-19. Despite the fact that no cure has been found for SARS-CoV-2, prevention methods such as vaccines, specific facial mask, and social distancing have proven to be quite effective. It is imperative to have a complete understanding of the transmission and pathogenesis of this virus. To effectively develop new drugs as well as diagnostic tools, more knowledge about this virus would be needed.

Analysis of Bacteriophage Behavior of a Human RNA Virus, SARS-CoV-2, through the Integrated Approach of Immunofluorescence Microscopy, Proteomics and D-Amino Acid Quantification

SARS-CoV-2, one of the human RNA viruses, is widely studied around the world. Significant efforts have been made to understand its molecular mechanisms of action and how it interacts with epithelial cells and the human microbiome since it has also been observed in gut microbiome bacteria. Many studies emphasize the importance of surface immunity and also that the mucosal system is critical in the interaction of the pathogen with the cells of the oral, nasal, pharyngeal, and intestinal epithelium. Recent studies have shown how bacteria in the human gut microbiome produce toxins capable of altering the classical mechanisms of interaction of viruses with surface cells. This paper presents a simple approach to highlight the initial behavior of a novel pathogen, SARS-CoV-2, on the human microbiome. The immunofluorescence microscopy technique can be combined with spectral counting performed at mass spectrometry of viral peptides in bacterial cultures, along with identification of the presence of D-amino acids within viral peptides in bacterial cultures and in patients' blood. This approach makes it possible to establish the possible expression or increase of viral RNA viruses in general and SARS-CoV-2, as discussed in this study, and to determine whether or not the microbiome is involved in the pathogenetic mechanisms of the viruses. This novel combined approach can provide information more rapidly, avoiding the biases of virological diagnosis and identifying whether a virus can interact with, bind to, and infect bacteria and epithelial cells. Understanding whether some viruses have bacteriophagic behavior allows vaccine therapies to be focused either toward certain toxins produced by bacteria in the microbiome or toward finding inert or symbiotic viral mutations with the human microbiome. This new knowledge opens a scenario on a possible future vaccine: the probiotics vaccine, engineered with the right resistance to viruses that attach to both the epithelium human surface and gut microbiome bacteria.

Korona Virüs Tanısı ve Biyosensörler

Hızla gelişen teknoloji dünyada dijitalleşme çağında laboratuvar tıbbının da bu gelişime ayak uydurarak sensör tabanlı ölçüm sistemlerinin kullanım alanları genişlemektedir. Biyosensörler kolay kullanımı, portatif olması, hızlı ve kesin sonuç vermesi gibi özelliklerinden dolayı salgın hastalık takibinde önemli rol oynayacaktır. Çin'in Wuhan şehrinde 2019 yılında ortaya çıkan korona virüs hastalığı pandemi haline dönüşmüştür. Pandeminin takibi ve kontrolü için tanı testleri geliştirilmesi ve tanı testlerinde kullanılacak örnek seçimi büyük önem kazanmıştır. Bu derlemede korona virüs hastalığının tanı ve takibinin günümüzde nasıl yapıldığı hakkında bilgi verip biyosensörlerin tanı ve takip amacıyla kullanılabilirliği hakkında bilgiler verilmektedir.

Toxin-like Peptides from the Bacterial Cultures Derived from Gut Microbiome Infected by SARS-CoV-2-New Data for a Possible Role in the Long COVID Pattern

It has been 3 years since the beginning of the SARS-CoV-2 outbreak, however it is as yet little known how to care for the acute COVID-19 and long COVID patients. COVID-19 clinical manifestations are of both pulmonary and extra-pulmonary types. Extra-pulmonary ones include extreme tiredness (fatigue), shortness of breath, muscle aches, hyposmia, dysgeusia, and other neurological manifestations. In other autoimmune diseases, such as Parkinson's disease (PD) or Alzheimer's Disease (AD), it is well known that role of acetylcholine is crucial in olfactory dysfunction. We have already observed the presence of toxin-like peptides in plasma, urine, and faecal samples from COVID-19 patients, which are very similar to molecules known to alter acetylcholine signaling. After observing the production of these peptides in bacterial cultures, we have performed additional proteomics analyses to better understand their behavior and reported the extended data from our latest in vitro experiment. It seems that the gut microbiome continues to produce toxin-like peptides also after the decrease of RNA SARS-CoV-2 viral load at molecular tests. These toxicological interactions between the gut/human microbiome bacteria and the virus suggest a new scenario in the study of the clinical symptoms in long COVID and also in acute COVID-19 patients. It is discussed that in the bacteriophage similar behavior, the presence of toxins produced by bacteria continuously after viral aggression can be blocked using an appropriate combination of certain drugs.

Milder symptoms and shorter course in patients with re-positive COVID-19: A cohort of 180 patients from Northeast China

China experienced another widespread Coronavirus disease 2019 (COVID-19) outbreak recently caused by the Omicron variant, which is less severe but far more contagious than the other COVID-19 variants, leading local governments to focus efforts on eliminating the spread of the disease. Previous studies showed that after "recovering" from the virus, some patients could re-test positive for COVID-19 with nucleic acid tests, challenging the control of disease spread. In this study, we aimed to analyze the clinical and laboratory characteristics of re-positive COVID-19 patients in Northeast China. We retrospectively analyzed data from confirmed reverse transcription polymerase chain reaction (RT-PCR) re-positive COVID-19 patients who were admitted to the First Hospital of Jilin University, Jilin Province, China, from March to June 2022. Detailed clinical symptoms, medical history, anti-Corona Virus (CoV) IgG and IgM levels, and CoV nucleic acid cycle threshold (Ct) values during the re-positive period were collected and analyzed. A total of 180 patients were included in this study, including 62 asymptomatic cases and 118 mild cases. The cohort included 113 men and 67 women, with an average age of 45.73 years. The median time between recovery from the virus and re-positivity was 13 days. Our results showed that the proportion of re-positive patients with symptoms was lower, and the nucleic acid test-positive duration was shorter during the re-positive period. Furthermore, in patients with underlying disease, the proportion of patients with symptoms was higher, anti-CoV IgG levels were lower, and the total disease duration was longer. In conclusion, during the re-positive period, the symptoms were milder, and the CoV nucleic acid test-positive course was shorter. The concomitant underlying disease is an important factor associated with clinical symptoms, and the overall course of COVID-19 re-positive patients may be associated with lower anti-CoV IgG levels. Large-scale and multicenter studies are recommended to better understand the pathophysiology of recurrence in patients with COVID-19.

GRP78, a Novel Host Factor for SARS-CoV-2: The Emerging Roles in COVID-19 Related to Metabolic Risk Factors

The outbreak of coronavirus disease 19 (COVID-19), caused by the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in an unprecedented amount of infection cases and deaths, leading to the global health crisis. Despite many research efforts, our understanding of COVID-19 remains elusive. Recent studies have suggested that cell surface glucose-regulated protein 78 (GRP78) acts as a host co-receptor for SARS-CoV-2 infection and is related to COVID-19 risks, such as older age, obesity, and diabetes. Given its significance in a wide range of biological processes, such as protein homeostasis and cellular signaling, GRP78 might also play an important role in various stages of the viral life cycle and pathology of SARS-CoV-2. In this perspective, we explore the emerging and potential roles of GRP78 in SARS-CoV-2 infection. Additionally, we discuss the association with COVID-19 risks and symptoms. We hope this review article will be helpful to understand COVID-19 pathology and promote attention and study of GRP78 from many clinical and basic research fields.

The STING Ligand and Delivery System Synergistically Enhance the Immunogenicity of an Intranasal Spike SARS-CoV-2 Vaccine Candidate

The respiratory organ serves as a primary target site for SARS-CoV-2. Thus, the vaccine-stimulating immune response of the respiratory tract is significant in controlling SARS-CoV-2 transmission and disease development. In this study, mucoadhesive nanoparticles were used to deliver SARS-CoV-2 spike proteins (S-NPs) into the nasal tracts of mice. The responses in the respiratory organ and the systemic responses were monitored. The administration of S-NPs along with cGAMP conferred a robust stimulation of antibody responses in the respiratory tract, as demonstrated by an increase of IgA and IgG antibodies toward the spike proteins in bronchoalveolar lavages (BALs) and the lungs. Interestingly, the elicited antibodies were able to neutralize both the wild-type and Delta variant strains of SARS-CoV-2. Significantly, the intranasal immunization also stimulated systemic responses. This is evidenced by the increased production of circulating IgG and IgA, which were able to neutralize and bind specifically to the SARS-CoV-2 virion and spike protein. Additionally, this intranasal administration potently activated a splenic T cell response and the production of Th-1 cytokines, suggesting that this vaccine may well activate a cellular response in the respiratory tract. The results demonstrate that STING agonist strongly acts as an adjuvant to the immunogenicity of S-NPs. This platform may be an ideal vaccine against SARS-CoV-2.

SARS-CoV-2: Reinfection after 18 Months of a Previous Case with Multiple Negative Nasopharyngeal Swab Tests and Positive Fecal Molecular Test

This short communication describes the reinfection after nearly 18 months of the same patient who was previously infected with coronavirus disease 2019 (COVID-19) and who showed multiple negative real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) results by nasal swabs for severe acute respiratory syndrome coronavirus (SARS-CoV-2) but positive results on a fecal sample. We previously noted how, in the presence of symptoms suggestive of pneumonia, visible on a chest computed tomography (CT) scan and confirmed by fecal molecular testing, it was possible to draw the diagnosis of SARS-CoV-2 infection. One year later, the same patient was again affected by SARS-CoV-2. This time, the first antigenic nasal swab showed readily positive results. However, the patient’s clinical course appeared to be more attenuated, showing no signs of pulmonary involvement in the radiographic examinations performed. This case shows a novelty in the pulmonary radiological evaluation of new SARS-CoV-2 infection.

Could SARS-CoV-2 Have Bacteriophage Behavior or Induce the Activity of Other Bacteriophages?

SARS-CoV-2 has become one of the most studied viruses of the last century. It was assumed that the only possible host for these types of viruses was mammalian eukaryotic cells. Our recent studies show that microorganisms in the human gastrointestinal tract affect the severity of COVID-19 and for the first time provide indications that the virus might replicate in gut bacteria. In order to further support these findings, in the present work, cultures of bacteria from the human microbiome and SARS-CoV-2 were analyzed by electron and fluorescence microscopy. The images presented in this article, in association with the nitrogen (¹⁵N) isotope-labeled culture medium experiment, suggest that SARS-CoV-2 could also infect bacteria in the gut microbiota, indicating that SARS-CoV-2 could act as a bacteriophage. Our results add new knowledge to the understanding of the mechanisms of SARS-CoV-2 infection and fill gaps in the study of the interactions between SARS-CoV-2 and non-mammalian cells. These findings could be useful in suggesting specific new pharmacological solutions to support the vaccination campaign.

Lymphopenia in patients affected by SARS-CoV-2 infection is caused by margination of lymphocytes in large bowel: an [18F]FDG PET/CT study

BACKGROUND

To investigate the cause of lymphopenia in patients with newly diagnosed COVID-19, we measured [¹⁸F]FDG uptake in several tissues, including the ileum, right colon, and caecum at diagnosis and after recovery and correlated these measurements with haematological parameters.

METHODS

We studied, by [¹⁸F]FDG PET/CT, 18 newly diagnosed patients with COVID-19. Regions of interest were drawn over major organs and in the terminal ileum, caecum, and right colon, where the bowel wall was evaluable. Five patients were re-examined after recovery, and three of them also performed a white blood cell scan with ^99mTc-HMPAO-WBC on both occasions. Complete blood count was performed on both occasions, and peripheral blood lymphocyte subsets were measured at diagnosis. Data were analysed by a statistician.

RESULTS

Patients had moderate severity COVID-19 syndrome. Basal [¹⁸F]FDG PET/CT showed focal lung uptake corresponding to hyperdense areas at CT. We also found high spleen, ileal, caecal, and colonic activity as compared to 18 control subjects. At recovery, hypermetabolic tissues tended to normalize, but activity in the caecum remained higher than in controls. Regression analyses showed an inverse correlation between CD4 + lymphocytes and [¹⁸F]FDG uptake in the caecum and colon and a direct correlation between CD8 + lymphocytes and [¹⁸F]FDG uptake in lungs and bone marrow. WBC scans showed the presence of leukocytes in the caecum and colon that disappeared at recovery.

CONCLUSIONS

These findings indicate that lymphopenia in COVID-19 patients is associated with large bowel inflammation supporting the hypothesis that CD4 + lymphocytes migrate to peripheral lymphoid tissues in the bowel.

Identification and Analysis of SARS-CoV-2 Alpha Variants in the Largest Taiwan COVID-19 Outbreak in 2021

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is believed to have originated in Wuhan City, Hubei Province, China, in December 2019. Infection with this highly dangerous human-infecting coronavirus via inhalation of respiratory droplets from SARS-CoV-2 carriers results in coronavirus disease 2019 (COVID-19), which features clinical symptoms such as fever, dry cough, shortness of breath, and life-threatening pneumonia. Several COVID-19 waves arose in Taiwan from January 2020 to March 2021, with the largest outbreak ever having a high case fatality rate (CFR) (5.95%) between May and June 2021. In this study, we identified five 20I (alpha, V1)/B.1.1.7/GR SARS-CoV-2 (KMUH-3 to 7) lineage viruses from COVID-19 patients in this largest COVID-19 outbreak. Sequence placement analysis using the existing SARS-CoV-2 phylogenetic tree revealed that KMUH-3 originated from Japan and that KMUH-4 to KMUH-7 possibly originated via local transmission. Spike mutations M1237I and D614G were identified in KMUH-4 to KMUH-7 as well as in 43 other alpha/B.1.1.7 sequences of 48 alpha/B.1.1.7 sequences deposited in GISAID derived from clinical samples collected in Taiwan between 20 April and July. However, M1237I mutation was not observed in the other 12 alpha/B.1.1.7 sequences collected between 26 December 2020, and 12 April 2021. We conclude that the largest COVID-19 outbreak in Taiwan between May and June 2021 was initially caused by the alpha/B.1.1.7 variant harboring spike D614G + M1237I mutations, which was introduced to Taiwan by China Airlines cargo crew members. To our knowledge, this is the first documented COVID-19 outbreak caused by alpha/B.1.1.7 variant harboring spike M1237I mutation thus far. The largest COVID-19 outbreak in Taiwan resulted in 13,795 cases and 820 deaths, with a high CFR, at 5.95%, accounting for 80.90% of all cases and 96.47% of all deaths during the first 2 years. The high CFR caused by SARS-CoV-2 alpha variants in Taiwan can be attributable to comorbidities and low herd immunity. We also suggest that timely SARS-CoV-2 isolation and/or sequencing are of importance in real-time epidemiological investigations and in epidemic prevention. The impact of D614G + M1237I mutations in the spike gene on the SARS-CoV-2 virus spreading as well as on high CFR remains to be elucidated.

Therapeutic and prophylactic effect of flavonoids in post-COVID-19 therapy

The high incidence of post-covid symptoms in humans confirms the need for effective treatment. Due to long-term complications across several disciplines, special treatment programs emerge for affected patients, emphasizing multidisciplinary care. For these reasons, we decided to look at current knowledge about possible long-term complications of COVID-19 disease and then present the effect of flavonoids, which could help alleviate or eliminate complications in humans after overcoming the COVID-19 infection. Based on articles published from 2003 to 2021, we summarize the flavonoids-based molecular mechanisms associated with the post-COVID-19 syndrome and simultaneously provide a complex view regarding their prophylactic and therapeutic potential. Review clearly sorts out the outcome of post-COVID-19 syndrome according particular body systems. The conclusion is that flavonoids play an important role in prevention of many diseases. We suggest that flavonoids as critical nutritional supplements, are suitable for the alleviation and shortening of the period associated with the post-COVID-19 syndrome. The most promising flavonoid with noteworthy therapeutic and prophylactic effect appears to be quercetin.

Whole-Genome Sequencing of SARS-CoV-2 Infection in a Cluster of Immunocompromised Children in Indonesia

Background

Thus far, Indonesia has recorded over 4,000,000 confirmed COVID-19 cases and 144,000 fatalities; 12.8% of cases have been in children under 18 years. Whole-genome viral sequencing (WGS) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been demonstrated to help differentiate hospital-acquired infection from community-acquired coronavirus disease 2019 (COVID-19) infection. Our study highlighted the use of WGS to investigate the origin of infection among pediatric oncology patients in Jakarta. The aim of our study was to evaluate clinical and laboratory characteristics and also the efficacy of using WGS to confirm hospital-acquired COVID-19 infection in a cluster of immunocompromised children within a single ward of a tertiary hospital in metropolitan Jakarta based on quasispecies, viral load, and admission dates.

Method

Real-time reverse-transcription polymerase chain reaction (RT-PCR) from nasopharyngeal (NP) swabs was used to diagnose the patients and also guardians and healthcare workers (HCWs) in the ward, followed by WGS of RT-PCR positive cases to establish their phylogenetic relationships.

Result

Using WGS, we showed that SARS-CoV-2 transmission in a cluster of children with underlying malignancy was characterized by high similarity of whole virus genome, which suggests nosocomial transmission.

Diagnostic techniques for COVID-19: A mini-review

COVID-19, a new respiratory infectious disease, was first reported at the end of 2019, in Wuhan, China. Now, COVID-19 is still causing major loss of human life and economic productivity in almost all countries around the world. Early detection, early isolation, and early diagnosis of COVID-19 patients and asymptomatic carriers are essential to blocking the spread of the pandemic. This paper briefly reviewed COVID-19 diagnostic assays for clinical application, including nucleic acid tests, immunological methods, and Computed Tomography (CT) imaging. Nucleic acid tests (NAT) target the virus genome and indicates the existence of the SARS-CoV-2 virus. Currently, real-time quantitative PCR (qPCR) is the most widely used NAT and, basically, is the most used diagnostic assay for COVID-19. Besides qPCR, many novel rapid and sensitive NAT assays were also developed. Serological testing (detection of serum antibodies specific to SARS-CoV-2), which belongs to the immunological methods, is also used in the diagnosis of COVID-19. The positive results of serological testing indicate the presence of antibodies specific to SARS-CoV-2 resulting from being infected with the virus. Viral antigen detection assays are also important immunological methods used mainly for rapid virus detection. However, only a few of these assays had been reported. CT imaging is still an important auxiliary diagnosis tool for COVID-19 patients, especially for symptomatic patients in the early stage, whose viral load is low and different to be identified by NAT. These diagnostic techniques are all good in some way and applying a combination of them will greatly improve the accuracy of COVID-19 diagnostics.

The importance of fecal nucleic acid detection in patients with coronavirus disease(COVID-19):a systematic review and meta-analysis

Pooled data from 2352 hospitalized coronavirus disease 2019 (COVID‐19) patients with viral RNA in feces across 46 studies were analyzed and the pooled prevalence of fecal RNA was 46.8% (95% confidence interval [CI]: 0.383–0.554). The pooled analysis showed that the occurrence of total gastrointestinal (GI) symptoms was 28.5% (95% CI: 0.125–0.44) in COVID‐19 patients with fecal RNA, that of both respiratory and GI symptoms was 21.9% (95% CI: 0.09–0.346), that of only GI symptoms was 19.8% (95% CI: 0.107–0.288), and that of only respiratory symptoms was 50.5%（95% CI: 0.267–0.744). The pooled data showed no significant difference in positive fecal RNA between severe and nonsevere cases (odds ratio = 2.009, p = 0.079, 95% CI: 0.922–4.378). During hospital admission, after samples from the respiratory system tested negative for viral RNA, 55.4% (95% CI: 0.418–0.669) of the patients with positive fecal RNA had persistent shedding of fecal RNA and pooled results from the other 4 studies including 848 discharged patients with nucleic acid‐negative stool samples indicated that the occurrence of repositive stool swabs was 18.1% (95% CI: 0.028–0.335), that of repositive respiratory swabs was 22.8% (95% CI: 0.003–0.452), that of both repositive stool and respiratory swabs was 19.1% (95% CI: 0.019–0.363), and that of only repositive stool swabs was 9.6% (95% CI: 0.010–0.203). The digestive tract may be an important organ involved in COVID‐19 infection and in the excretion of the virus. Because of the potential risk of fecal–oral transmission, giving emphasis on stool swab tests can help increase the detection rate of asymptomatic carriers and reduce missed diagnoses.

Isolation and Identification of a Rare Spike Gene Double-Deletion SARS-CoV-2 Variant From the Patient With High Cycle Threshold Value

Coronavirus disease 2019 (COVID-19) is an emerging life-threatening pulmonary disease caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in Wuhan, Hubei Province, China, in December 2019. COVID-19 develops after close contact via inhalation of respiratory droplets containing SARS-CoV-2 during talking, coughing, or sneezing by asymptomatic, presymptomatic, and symptomatic carriers. This virus evolved over time, and numerous genetic variants have been reported to have increased disease severity, mortality, and transmissibility. Variants have also developed resistance to antivirals and vaccination and can escape the immune response of humans. Reverse transcription polymerase chain reaction (RT-PCR) is the method of choice among diagnostic techniques, including nucleic acid amplification tests (NAATs), serological tests, and diagnostic imaging, such as computed tomography (CT). The limitation of RT-PCR is that it cannot distinguish fragmented RNA genomes from live transmissible viruses. Thus, SARS-CoV-2 isolation by using cell culture has been developed and makes important contributions in the field of diagnosis, development of antivirals, vaccines, and SARS-CoV-2 virology research. In this research, two SARS-CoV-2 strains were isolated from four RT-PCR-positive nasopharyngeal swabs using VERO E6 cell culture. One isolate was cultured successfully with a blind passage on day 3 post inoculation from a swab with a Ct > 35, while the cells did not develop cytopathic effects without a blind passage until day 14 post inoculation. Our results indicated that infectious SARS-CoV-2 virus particles existed, even with a Ct > 35. Cultivable viruses could provide additional consideration for releasing the patient from quarantine. The results of the whole genome sequencing and bioinformatic analysis suggested that these two isolates contain a spike 68-76del+spike 675-679del double-deletion variation. The double deletion was confirmed by amplification of the regions spanning the spike gene deletion using Sanger sequencing. Phylogenetic analysis revealed that this double-deletion variant was rare (one per million in public databases, including GenBank and GISAID). The impact of this double deletion in the spike gene on the SARS-CoV-2 virus itself as well as on cultured cells and/or humans remains to be further elucidated.

Could Small Neurotoxins-Peptides be Expressed during SARS-CoV-2 Infection?

SARS-CoV-2 pathogenesis has been recently extended to human central nervous system (CNS), in addition to nasopharyngeal truck, eye, lung and gut. The recent literature highlights that some SARS-CoV-2 spike glycoprotein regions homologous to neurotoxin-like peptides might bind to human nicotinic Acetyl-Choline Receptors (nAChRs). Spike-nAChR interaction can probably cause dysregulation of CNS and cholinergic anti-inflammatory pathways and uncontrolled immune-response, both associated to a severe COVID-19 pathophysiology. Herein, we hypothesize that inside the Open Reading Frame (ORF) region of spike glycoprotein, the RNA polymerase can translate small neurotoxic peptides by means of a "jumping mechanism" already demonstrated in other coronaviruses. These small peptides can bind the snAChRs instead of Spike glycoproteins. A striking homology occurred between these small peptides observed by sequence retrieval and proteins alignment. Acting as nAChRs antagonists, these small peptides (conotoxins) could be the explanation for the extrapulmonary clinical manifestations (neurological, hemorrhagic and thrombotic expressions, the prolonged apnea, the cardiocirculatory collapse, the heart arrhythmias, the ventricular tachycardia, the body temperature alteration, the electrolyte K+ imbalance and finally the significant reduction of butyryl cholinesterase (BuChE) plasma levels, as observed in COVID-19 patients. Several factors might induce the expression of these small peptides, including microbiota. The main hypothesis regarding the presence of these small peptides opens a new scenario on the etiology of COVID-19 clinical symptoms observed so far, including the neurological manifestations.

COVID-19 Pneumonia in Vaccinated Population: A Six Clinical and Radiological Case Series

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) and its related disease (COVID-19) continue to represent a challenge for humans. To date, vaccination programs have represented an opportunity to navigate the pandemic. However, the advent of new genetic COVID-19 variants has increased more attention representing a worrying threat not only for not vaccinated but also for vaccinated people as virus infections have been shown also in the last ones. Herein, we report different clinical cases and radiological findings of COVID-19 pneumonia in six fully vaccinated patients. Two patients had a history of Rituximab therapy for follicular lymphoma and with persistent positivity for SARS-CoV-2 on nasopharyngeal/oropharyngeal (NP/OP) swabs and with moderate pneumonia on the chest computed tomography (CT). One patient who resulted to be positive to delta variant 8 days after the second vaccination dose, died shortly after. Two patients were hospitalized due to the worsening of fever and dyspnea in presence of mild pneumonia on CT. In one patient mild pneumonia was found on the chest-CT performed after a lipothymic episode associated with chest pain and positive NP/OP swab tested for SARS-CoV-2. These data suggested that in fully vaccinated people, caution should be preserved, and the use of masks and social distancing should be continued in all closed environments. However, further clinical trials should be done to better understand how various factors can influence vaccine immunogenicity as the presence of virus mutations, age factors, and the presence of an immunocompromised state.

[Efficacy and Safety of Fecal Microbiota Transplantation and Prospect of Microbe-based Therapies for Inflammatory Bowel Disease]

The use of 5-ASA, immunomodulators, biologics, and small molecule drugs are the main treatment for inflammatory bowel disease (IBD), however, fecal microbiota transplantation (FMT) is also drawing attention as a treatment to improve intestinal dysbiosis by transplantaing normal human stool into patients with IBD. FMT demonstrates relatively good effects in inducing clinical remission in IBD, but unlike Clostridium difficile infection, multiple FMT can enhance the clinical effect. There are no reports of the long-term effectiveness and safety of FMT conducted in IBD yet, therefore, well-designed, prospective studies will be needed. Gut microbiota can affect inflammatory response, intestinal barrier function, and host metabolism, so microbe-based therapies are likely to be a new treatment option for IBD. The deeper the understanding of microbe products or effectors, the more likely it is to provide personalized therapy in IBD.

Increase of SARS-CoV-2 RNA load in faecal samples prompts for rethinking of SARS-CoV-2 biology and COVID-19 epidemiology

Background Scientific evidence for the involvement of human microbiota in the development of COVID-19 disease has been reported recently. SARS-CoV-2 RNA presence in human faecal samples and SARS-CoV-2 activity in faeces from COVID-19 patients have been observed. Methods Starting from these observations, an experimental design was developed to cultivate in vitro faecal microbiota from infected individuals, to monitor the presence of SARS-CoV-2, and to collect data on the relationship between faecal bacteria and the virus. Results Our results indicate that SARS-CoV-2 replicates in vitro in bacterial growth medium, that the viral replication follows bacterial growth and it is influenced by the administration of specific antibiotics. SARS-CoV-2-related peptides have been detected in 30-day bacterial cultures and characterised. Discussion Our observations are compatible with a 'bacteriophage-like' behaviour of SARS-CoV-2, which, to our knowledge has not been observed or described before. These results are unexpected and hint towards a novel hypothesis on the biology of SARS-CoV-2 and on the COVID-19 epidemiology. The discovery of possible new modes of action of SARS-CoV-2 has far-reaching implications for the prevention and the treatment of the disease.

Increase of SARS-CoV-2 RNA load in faecal samples prompts for rethinking of SARS-CoV-2 biology and COVID-19 epidemiology

Background Scientific evidence for the involvement of human microbiota in the development of COVID-19 disease has been reported recently. SARS-CoV-2 RNA presence in human faecal samples and SARS-CoV-2 activity in faeces from COVID-19 patients have been observed. Methods Starting from these observations, an experimental design was developed to cultivate in vitro faecal microbiota from infected individuals, to monitor the presence of SARS-CoV-2, and to collect data on the relationship between faecal bacteria and the virus. Results Our results indicate that SARS-CoV-2 replicates in vitro in bacterial growth medium, that the viral replication follows bacterial growth and it is influenced by the administration of specific antibiotics. SARS-CoV-2-related peptides have been detected in 30-day bacterial cultures and characterised. Discussion Our observations are compatible with a 'bacteriophage-like' behaviour of SARS-CoV-2, which, to our knowledge has not been observed or described before. These results are unexpected and hint towards a novel hypothesis on the biology of SARS-CoV-2 and on the COVID-19 epidemiology. The discovery of possible new modes of action of SARS-CoV-2 has far-reaching implications for the prevention and the treatment of the disease.

Increase of SARS-CoV-2 RNA load in faecal samples prompts for rethinking of SARS-CoV-2 biology and COVID-19 epidemiology

Background Scientific evidence for the involvement of human microbiota in the development of COVID-19 disease has been reported recently. SARS-CoV-2 RNA presence in human faecal samples and SARS-CoV-2 activity in faeces from COVID-19 patients have been observed. Methods Starting from these observations, an experimental design was developed to cultivate in vitro faecal microbiota from infected individuals, to monitor the presence of SARS-CoV-2, and to collect data on the relationship between faecal bacteria and the virus. Results Our results indicate that SARS-CoV-2 replicates in vitro in bacterial growth medium, that the viral replication follows bacterial growth and it is influenced by the administration of specific antibiotics. SARS-CoV-2-related peptides have been detected in 30-day bacterial cultures and characterised. Discussion Our observations are compatible with a 'bacteriophage-like' behaviour of SARS-CoV-2, which, to our knowledge has not been observed or described before. These results are unexpected and hint towards a novel hypothesis on the biology of SARS-CoV-2 and on the COVID-19 epidemiology. The discovery of possible new modes of action of SARS-CoV-2 has far-reaching implications for the prevention and the treatment of the disease.

Review of Current COVID-19 Diagnostics and Opportunities for Further Development

Diagnostic testing plays a critical role in addressing the coronavirus disease 2019 (COVID-19) pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Rapid and accurate diagnostic tests are imperative for identifying and managing infected individuals, contact tracing, epidemiologic characterization, and public health decision making. Laboratory testing may be performed based on symptomatic presentation or for screening of asymptomatic people. Confirmation of SARS-CoV-2 infection is typically by nucleic acid amplification tests (NAAT), which requires specialized equipment and training and may be particularly challenging in resource-limited settings. NAAT may give false-negative results due to timing of sample collection relative to infection, improper sampling of respiratory specimens, inadequate preservation of samples, and technical limitations; false-positives may occur due to technical errors, particularly contamination during the manual real-time polymerase chain reaction (RT-PCR) process. Thus, clinical presentation, contact history and contemporary phyloepidemiology must be considered when interpreting results. Several sample-to-answer platforms, including high-throughput systems and Point of Care (PoC) assays, have been developed to increase testing capacity and decrease technical errors. Alternatives to RT-PCR assay, such as other RNA detection methods and antigen tests may be appropriate for certain situations, such as resource-limited settings. While sequencing is important to monitor on-going evolution of the SARS-CoV-2 genome, antibody assays are useful for epidemiologic purposes. The ever-expanding assortment of tests, with varying clinical utility, performance requirements, and limitations, merits comparative evaluation. We herein provide a comprehensive review of currently available COVID-19 diagnostics, exploring their pros and cons as well as appropriate indications. Strategies to further optimize safety, speed, and ease of SARS-CoV-2 testing without compromising accuracy are suggested. Access to scalable diagnostic tools and continued technologic advances, including machine learning and smartphone integration, will facilitate control of the current pandemic as well as preparedness for the next one.