Why Do Some People Develop Serious COVID-19 Disease After Infection, While Others Only Exhibit Mild Symptoms?

Guardians at the gate: Unraveling Type I interferon's role and challenges posed by anti-interferon antibodies in COVID-19

The intricate interplay involving Type I interferon (IFN), anti-interferon antibodies, and COVID-19 elucidates a complex symphony within the immune system. This chapter thoroughly explores the dynamic landscape of Type I IFN, delineating its pivotal role as the guardian of the immune response. As SARS-CoV-2 engages the host, the delicate balance of IFN induction and signaling pathways is disrupted, resulting in a nuanced impact on the severity and pathogenesis of COVID-19. Clinical studies illuminate a critical link between impaired IFN response and severe outcomes, uncovering genetic factors contributing to susceptibility. Furthermore, the emergence of anti-interferon antibodies proves to be a disruptive force, compromising the immune arsenal and correlating with disease severity. Our chapter encompasses diagnostic and prognostic implications, highlighting the importance of assays in identifying levels of IFN and anti-interferon antibodies. This chapter examines the possible incorporation of interferon-related biomarkers in COVID-19 diagnostics, offering predictive insights into disease progression. On the therapeutic front, efforts to manipulate the IFN pathway undergo scrutiny, encountering complexities in light of anti-interferon antibodies. This chapter concludes by outlining prospective avenues for precision medicine, emphasizing the imperative need for a comprehensive comprehension of the IFN landscape and its intricate interaction with COVID-19.

Pulmonary Myeloid Cells in Mild Cases of COVID-19 Upregulate the Intracellular Fc Receptor TRIM21 and Transcribe Proteasome-Associated Molecules

Much remains to be understood about COVID-19, but the protective role of antibodies (Igs) is widely accepted in SARS-CoV-2 infection. Igs' functions are mainly carried out by receptors that bind to their Fc portion (FcR), and less attention has been dedicated to the cytoplasmic members of this family. In this work, we used single-cell RNA sequencing (scRNA-seq) data to discern cell populations in bronchoalveolar lavage fluid obtained from healthy individuals and patients with mild or severe COVID-19. Then, we evaluated the transcription of neonatal FcR (FcRn, FCGRT gene) and tripartite motif-containing protein 21 (TRIM21) and its downstream signaling components. The TRIM21 pathway is vital for virus infections as it has a dual function, leading opsonized viruses to degradation by proteasomes and the activation of innate inflammatory anti-virus response. The transcriptional level of FCGRT showed no statistical differences in any cell population comparing the three groups of patients. On the other hand, TRIM21 transcription was significantly higher in myeloid cells collected from patients with mild COVID-19. When comparing mild with severe cases, there was no statistical difference in TRIM21 transcription in lung adaptive lymphoid cells and innate lymphoid cells (ILC). Yet, we analyzed the transcription of all downstream signaling molecules in myeloid and, as most cells expressed the receptor, in adaptive lymphoid cells. Moreover, ILCs from mild cases and all cell populations from severe cases were missing most downstream components of the pathway. We observed that members of the ubiquitin-proteasome system (UPS) and other components associated with TRIM21 proteasomal degradation were transcribed in mild cases. Despite the transcription of the danger sensors DDX58 and IFIH1, the transcriptional level of inflammatory IL1B and IL18 was generally very low, along with the NLRP3 danger sensor, members of the NF-κB pathway, and TNF. Therefore, our data suggest that TRIM21 may contribute to SARS-CoV-2 protection by reducing the viral load, while the inflammatory branch of the pathway would be silenced, leading to no pathogenic cytokine production.

FIB-4 Index Can Predict Mortality in Hospitalized Patients with COVID-19 Infection, Independent of CT Severity Score

BACKGROUND

The fibrosis 4 (FIB-4) index is typically used in assessing liver fibrosis, and has shown potential in predicting the outcome in various diseases. This study aims to evaluate the predictive power of the FIB-4 index for mortality in COVID-19 patients admitted to a reference hospital in Tehran, Iran.

METHODS

In this prospective cohort study, 387 patients with COVID-19 without diabetes, were categorized into deceased and surviving groups. We compared anthropometric and demographic data, liver function tests, CT scores, and FIB-4 indices between the groups. Multivariate logistic regression assessed the independent association of FIB-4 with mortality.

RESULTS

Among the 387 patients, (all non-diabetics), 58 (15%) died, with a higher mortality rate observed in patients with a FIB-4 index≥2.6 (63.4%) compared to those with FIB-4<2.6 (29.7%). Deceased patients were considerably older and more likely to be hypertensive (P values<0.001). After adjustment of confounding factors, a FIB-4 index≥2.6 was found to be independently associated with increased mortality (OR: 13.511, 95% CI: 1.356-134.580, P=0.026).

CONCLUSION

The FIB-4 index, calculable by routine laboratory tests, may be a valuable prognostic factor for COVID-19 mortality. This easily obtainable marker could help identify high-risk patients early, potentially allowing for more rapid intervention and treatment prioritization.

Host genetics and COVID-19 severity: increasing the accuracy of latest severity scores by Boolean quantum features

The impact of common and rare variants in COVID-19 host genetics has been widely studied. In particular, in Fallerini et al. (Human genetics, 2022, 141, 147-173), common and rare variants were used to define an interpretable machine learning model for predicting COVID-19 severity. First, variants were converted into sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. After that, the Boolean features, selected by these logistic models, were combined into an Integrated PolyGenic Score (IPGS), which offers a very simple description of the contribution of host genetics in COVID-19 severity.. IPGS leads to an accuracy of 55%-60% on different cohorts, and, after a logistic regression with both IPGS and age as inputs, it leads to an accuracy of 75%. The goal of this paper is to improve the previous results, using not only the most informative Boolean features with respect to the genetic bases of severity but also the information on host organs involved in the disease. In this study, we generalize the IPGS adding a statistical weight for each organ, through the transformation of Boolean features into "Boolean quantum features," inspired by quantum mechanics. The organ coefficients were set via the application of the genetic algorithm PyGAD, and, after that, we defined two new integrated polygenic scores (IPGS p h 1 and IPGS p h 2 ). By applying a logistic regression with both IPGS, (IPGS p h 2 (or indifferently IPGS p h 1 ) and age as inputs, we reached an accuracy of 84%-86%, thus improving the results previously shown in Fallerini et al. (Human genetics, 2022, 141, 147-173) by a factor of 10%.

Association between salivary proteases and protease inhibitors linked with viral infections and oral inflammatory diseases

INTRODUCTION

Despite the role of transmembrane protease, serine 2 (TMPRSS2) in facilitating the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the primary cause of the global COVID-19 pandemic, the interaction of extracellular and intracellular proteases in this process remains poorly elucidated. Thus, we monitored the salivary expression concentration (SEC) of TMPRSS2 and its inhibitor, alpha-1 antitrypsin (A1AT), and investigated whether oral inflammatory diseases affected the SEC of both proteins.

MATERIALS AND METHODS

We collected saliva samples before and after surgical treatment of inflammatory cystic diseases (radicular and inflammatory dentigerous cysts) in 25 patients. The SEC of TMPRSS2 and A1AT was measured using enzyme-linked immunosorbent assay. SEC in multiple patient status groups and subgroups of each status were investigated. Finally, the correlation between TMPRSS2 and A1AT SEC was analyzed.

RESULTS

The TMPRSS2 and A1AT SEC did not significantly change pre- or post-treatment. The TMPRSS2 SEC was significantly higher before and after treatment in patients aged >50 years, patients with radicular cysts, and patients with the basic disease. A1AT SEC was significantly decreased after treatment in the acute inflammation, large-sized, and patients without basic disease groups. No significant correlation was observed between the SEC of either protein before and after treatment.

DISCUSSION

Individual-specific SEC for TMPRSS2 may be influenced by age, lesion type, and basic disease; however, oral inflammatory diseases may not have a direct effect. Moreover, the extent of oral inflammatory diseases and the presence of basic diseases may be associated with A1AT SEC. Furthermore, the SEC between the two proteins may be independent.

HLA-Bw4 in association with KIR3DL1 favors natural killer cell-mediated protection against severe COVID-19

Replicating SARS-CoV-2 has been shown to degrade HLA class I on target cells to evade the cytotoxic T-cell (CTL) response. HLA-I downregulation can be sensed by NK cells to unleash killer cell immunoglobulin-like receptor (KIR)-mediated self-inhibition by the cognate HLA-I ligands. Here, we investigated the impact of HLA and KIR genotypes and HLA-KIR combinations on COVID-19 outcome. We found that the peptide affinities of HLA alleles were not correlated with COVID-19 severity. The predicted poor binders for SARS-CoV-2 peptides belong to HLA-B subtypes that encode KIR ligands, including Bw4 and C1 (introduced by B*46:01), which have a small F pocket and cannot accommodate SARS-CoV-2 CTL epitopes. However, HLA-Bw4 weak binders were beneficial for COVID-19 outcome, and individuals lacking the HLA-Bw4 motif were at higher risk for serious illness from COVID-19. The presence of the HLA-Bw4 and KIR3DL1 combination had a 58.8% lower risk of developing severe COVID-19 (OR = 0.412, 95% CI = 0.187-0.904, p = 0.02). This suggests that HLA-Bw4 alleles that impair their ability to load SARS-CoV-2 peptides will become targets for NK-mediated destruction. Thus, we proposed that the synergistic responsiveness of CTLs and NK cells can efficiently control SARS-CoV-2 infection and replication, and NK-cell-mediated anti-SARS-CoV-2 immune responses being mostly involved in severe infection when the level of ORF8 is high enough to degrade HLA-I. The HLA-Bw4/KIR3DL1 genotype may be particularly important for East Asians undergoing COVID-19 who are enriched in HLA-Bw4-inhibitory KIR interactions and carry a high frequency of HLA-Bw4 alleles that bind poorly to coronavirus peptides.

Impact of SARS-CoV-2 infection on patients with systemic lupus erythematosus in England prior to vaccination: a retrospective observational cohort study

OBJECTIVES

Determine the prevaccination healthcare impact of COVID-19 in patients with systemic lupus erythematosus (SLE) in England.

DESIGN

Retrospective cohort study of adult patients with SLE from 1 May to 31 October 2020.

SETTING

Clinical Practice Research Datalink (CPRD) Aurum and Hospital Episode Statistics (HES) databases from general practitioners across England combining primary care and other health-related data.

PARTICIPANTS

Overall, 6145 adults with confirmed SLE diagnosis ≥1 year prior to 1 May 2020 were included. Most patients were women (91.0%), white (67.1%), and diagnosed with SLE at age <50 (70.8%). Patients were excluded if they had a COVID-19 diagnosis before 1 May 2020.

PRIMARY AND SECONDARY OUTCOME MEASURES

Demographics and clinical characteristics were compared. COVID-19 severity was determined by patient care required and procedure/diagnosis codes. COVID-19 cumulative incidence, hospitalisation rates, lengths of stay and mortality rates were determined and stratified by SLE and COVID-19 severity.

RESULTS

Of 6145 patients, 3927 had mild, 1288 moderate and 930 severe SLE at baseline. The majority of patients with moderate to severe SLE were on oral corticosteroids and antimalarial treatments. Overall, 54/6145 (0.88%) patients with SLE acquired and were diagnosed with COVID-19, with 45 classified as mild, 6 moderate and 3 severe COVID-19. Cumulative incidence was higher in patients with severe SLE (1.4%) compared with patients classified as mild (0.8%) or moderate (0.8%). Ten COVID-19-specific hospital admissions occurred (n=6 moderate; n=4 severe). Regardless of COVID-19 status, hospital admission rates and length of stay increased with SLE severity. Of 54 patients with SLE diagnosed with COVID-19, 1 (1.9%) COVID-19-related death was recorded in a patient with both severe SLE and severe COVID-19.

CONCLUSIONS

SLE severity did not appear to impact COVID-19 outcomes in this study. The COVID-19 pandemic is evolving and follow-up studies are needed to understand the relationship between COVID-19 and SLE.

Clinical analysis of prolonged viral clearance time in patients with lymphoma combined with novel coronavirus infection

Objective: To compare the period of viral clearance and its influencing factors after severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection between patients with lymphoma and lung cancer. Methods: We retrospectively collected the clinical data of patients with lymphoma and lung cancer (118 cases) diagnosed with SARS-CoV-2 infection and hospitalized in the First Affiliated Hospital of Anhui Medical University between 1 December 2022, and 15 March 2023. Finally, 87 patients with prolonged virus clearance times were included and divided into lymphoma (40 cases) and lung cancer (47 cases) groups. We used the Kaplan-Meier method to draw a negative turn curve. We performed a univariate analysis of the prolongation of virus clearance time and a Cox regression model for multivariate analysis. Results: The median times for viral clearance in the lung cancer and lymphoma groups were 18 (95% confidence interval [CI] 15.112-20.888) and 32 (95%CI 27.429-36.571) days, respectively. Log-rank analysis showed a statistically significant difference (p = 0.048), and the lymphocyte count in the lymphoma group was lower than that in the lung cancer group (p = 0.044). We used the Cox regression model to conduct a multivariate analysis, which revealed that in lymphoma patients, the interval between the time of diagnosis and the time of SARS-CoV-2 infection <24 months (hazard ratio [HR]: 0.182, 95%CI: 0.062-0.535, p = 0.02), an interval between the last anti-CD20 monoclonal antibody treatment and the time of SARS-CoV-2 infection of <2 months (HR: 0.101, 95%CI: 0.029-0.358, p < 0.001), and a decrease in peripheral blood lymphocyte levels (HR: 0.380, 95%CI: 0.179-0.808, p = 0.012) were independent risk factors for prolonged viral clearance time. Conclusion: Patients with lymphoma combined with SARS-CoV-2 infection had a longer virus clearance time than did patients with lung cancer. Moreover, the lymphocyte count in the lymphoma group was lower than that in the lung cancer group; therefore, the immune status of patients with lymphoma is lower than that of patients with lung cancer. An interval between lymphoma diagnosis and SARS-CoV-2 infection of <2 years, anti-CD20 monoclonal antibody treatment within the past 2 months, and a decrease in lymphocyte levels in the peripheral blood prolonged the virus clearance time in the patients in this study.

Which vertebral level should be used to calculate sarcopenia in covid-19 patients? A systematic review and meta-analysis

BACKGROUND & AIMS

Evidence shows that CT-derived sarcopenia can predict adverse outcomes in COVID-19 patients. However, discrepancies exist as to which vertebral level can be used to calculate sarcopenia which can effectively serve as a prognostic tool. Thus, we aim to investigate the difference in sarcopenia calculated at the Thoracic and Lumbar vertebral levels.

METHODS

An online literature search was conducted on Electronic databases such as PubMed, Cochrane CENTRAL, and Google scholar. Meta-analysis was performed by using Revman 5.3 software.

RESULTS

A total of 14 articles were selected for meta-analysis. The prevalence of sarcopenia calculated at the Thoracic level was 31% (95%CI 24%-37%; p < 0.00001; I² = 86%), while sarcopenia calculated at the Lumbar vertebral level was 63% (95%CI 51%-75%; p < 0.00001; I² = 88%). Meanwhile, sarcopenia calculated at the Upper thoracic level was a significant predictor of mortality OR 3.47 (95%CI 1.74-6.91; p = 0.0004; I² = 56%)as compared to sarcopenia calculated at the lower thoracic OR 1.74 (95%Cl 0.91-3.33; p = 0.10; I² = 60%)or lumbar level OR 2.49 (95%CI 0.45-13.72; p = 0.30; I² = 57%). In addition to this sarcopenia calculated at the Upper thoracic level was also a significant predictor of severe illness OR 3.92 (95%CI 2.33-6.58; p < 0.00001; I² = 0%) as compared to lower thoracic OR 1.40 (95%CI 0.78-2.53; p = 0.26; I² = 67%) or lumbar level OR 1.64 (95%CI 0.26-10.50; p = 0.60; I² = 81%) CONCLUSIONS: Sarcopenia calculated at the thoracic vertebrae and lumber level has different prognostic values. Sarcopenia is prevalent at the lumbar level. Sarcopenia at the thoracic level has a higher mortality and severity rate.

Is COVID-19 severity associated with telomere length? A systematic review and meta-analysis

Telomere shortening, a marker of cellular aging, has been linked to hospitalization and the severity of COVID-19. In this systematic review and meta-analysis, the mean difference in telomere length between non-severe and severe COVID-19 individuals was pooled to determine the association between short telomeres and COVID-19 severity. Relevant studies were retrieved through searches conducted in PubMed-Medline, Scopus, EMBASE, Medrxiv, Biorxiv, EuroPMC, and SSRN databases up to November 2022. Selected studies were systematically reviewed and assessed for risk of bias using AXIS tool. The standardized mean difference in telomere length between non-severe and severe COVID-19 was pooled using random-effects model. A total of thirteen studies were included in the review, out of which seven (1332 patients with the severe COVID-19 disease and 6321 patients with non-severe COVID-19) were eligible for meta-analysis. The estimated pooled mean difference in Leukocyte telomere length between severe COVID-19 and non-severe COVID-19 was 0.39 (95% CI - 0.02 to 0.81, I2 = 93.5%) with substantial heterogeneity. Our findings do not provide clear evidence for association of shorter telomere length and severe COVID-19 disease. More extensive studies measuring absolute telomere length with age and gender adjustments are needed to draw definitive conclusions on the potential causal association between telomere shortening and COVID-19 severity.

Effects of Epitranscriptomic RNA Modifications on the Catalytic Activity of the SARS-CoV-2 Replication Complex

SARS-CoV-2 causes individualized symptoms. Many reasons have been given. We propose that an individual's epitranscriptomic system could be responsible as well. The viral RNA genome can be subject to epitranscriptomic modifications, which can be different for different individuals, and thus epitranscriptomics can affect many events including RNA replication differently. In this context, we studied the effects of modifications including pseudouridine (Ψ), 5-methylcytosine (m5 C), N6-methyladenosine (m6 A), N1-methyladenosine (m1 A) and N3-methylcytosine (m3 C) on the activity of SARS-CoV-2 replication complex (SC2RC). We found that Ψ, m5 C, m6 A and m3 C had little effect, whereas m1 A inhibited the enzyme. Both m1 A and m3 C disrupt canonical base pairing, but they had different effects. The fact that m1 A inhibits SC2RC implies that the modification can be difficult to detect. This fact also implies that individuals with upregulated m1 A including cancer, obesity and diabetes patients might have milder symptoms. However, this contradicts clinical observations. Relevant discussions are provided.

In silico transcriptional analysis of asymptomatic and severe COVID-19 patients reveals the susceptibility of severe patients to other comorbidities and non-viral pathological conditions

COVID-19 is a severe respiratory disease caused by SARS-CoV-2, a novel human coronavirus. Patients infected with SARS-CoV-2 exhibit heterogeneous symptoms that pose pragmatic hurdles for implementing appropriate therapy and management of the COVID-19 patients and their post-COVID complications. Thus, understanding the impact of infection severity at the molecular level in the host is vital to understand the host response and accordingly it's precise management. In the current study, we performed a comparative transcriptomics analysis of publicly available seven asymptomatic and eight severe COVID-19 patients. Exploratory data analysis employing Principal Component Analysis (PCA) showed the distinct clusters of asymptomatic and severe patients. Subsequently, the differential gene expression analysis using DESeq2 identified 1224 significantly upregulated genes (logFC≥ 1.5, p-adjusted value <0.05) and 268 significantly downregulated genes (logFC≤ −1.5, p-adjusted value <0.05) in severe samples in comparison to asymptomatic samples. Eventually, Gene Set Enrichment Analysis (GSEA) revealed the upregulation of anti-viral and anti-inflammatory pathways, secondary infections, Iron homeostasis, anemia, cardiac-related, etc.; while, downregulation of lipid metabolism, adaptive immune response, translation, recurrent respiratory infections, heme-biosynthetic pathways, etc. Conclusively, these findings provide insight into the enhanced susceptibility of severe COVID-19 patients to other health comorbidities including non-viral pathogenic infections, atherosclerosis, autoinflammatory diseases, anemia, male infertility, etc. owing to the activation of biological processes, pathways and molecular functions associated with them. We anticipate this study will facilitate the researchers in finding efficient therapeutic targets and eventually the clinicians in management of COVID-19 patients and post-COVID-19 effects in them.

Characteristics of the Severe Acute Respiratory Syndrome Coronavirus 2 Omicron BA.2 Subvariant in Jilin, China from March to May 2022

Background and Objectives

In the midst of the pandemic, new coronavirus mutants continue to emerge; the most relevant variant worldwide is omicron. Here, patients who recovered from the disease living in Jilin Province were analyzed to identify factors affecting the severity of omicron infection and to provide insights into its spread and early indication.

Methods

In this study, 311 cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were divided into two groups. Data on the patients' demographic characteristics and laboratory tests, including platelet count (PLT), neutrophil count (NE), C-reactive protein (CRP), serum creatinine (SCR), and neutrophil-to-lymphocyte ratio (NLR), were collected. The biomarkers for moderate and severe coronavirus disease 2019 (COVID-19) and factors affecting the incubation period and time to subsequent negative nucleic acid amplification test (NAAT) were also investigated.

Results

Age, gender, vaccination, hypertension, stroke, chronic obstructive pulmonary disease (COPD)/chronic bronchitis/asthma, and some laboratory tests were statistically different between the two groups. In the receiver operating characteristic (ROC) analysis, PLT and CRP had higher area under the ROC curve values. In the multivariate analysis, age, hypertension, COPD/chronic bronchitis/asthma, and CRP were correlated with moderate and severe COVID-19. Moreover, age was correlated with longer incubation. In the Kaplan-Meier curve analysis, gender (male), CRP, and NLR were associated with longer time to subsequent negative NAAT.

Conclusions

Older patients with hypertension and lung diseases were likely to have moderate or severe COVID-19, and younger patients might have a shorter incubation. A male patient with high CRP and NLR levels might take more time to turn back negative in the NAAT.

Pathogenic Mechanism and Multi-omics Analysis of Oral Manifestations in COVID-19

Coronavirus disease 2019 (COVID-19) is a respiratory infectious disease that seriously threatens human life. The clinical manifestations of severe COVID-19 include acute respiratory distress syndrome and multiple organ failure. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of COVID-19, spreads through contaminated droplets. SARS-CoV-2 particles have been detected in the saliva of COVID-19 patients, implying that the virus can infect and damage the oral cavity. The oral manifestations of COVID-19 include xerostomia and gustatory dysfunction. Numerous studies showed that the four structural proteins of SARS-CoV-2 are its potential pathogenic factors, especially the S protein, which binds to human ACE2 receptors facilitating the entry of the virus into the host cells. Usually, upon entry into the host cell, a pathogen triggers the host’s immune response. However, a mount of multi-omics and immunological analyses revealed that COVID-19 is caused by immune dysregulation. A decrease in the number and phenotypes of immune cells, IFN-1 production and excessive release of certain cytokines have also been reported. In conclusion, this review summarizes the oral manifestations of COVID-19 and multi-omics analysis of SARS-CoV-2 infection.

Approach to the management of COVID-19 patients: When home care can represent the best practice

BACKGROUND

The pandemic that began around February 2020, caused by the viral pathogen SARS-CoV-2 (COVID-19), has still not completed its course at present in June 2022.

OBJECTIVE

The open research to date highlights just how varied and complex the outcome of the contagion can be.

METHOD

The clinical pictures observed following the contagion present variabilities that cannot be explained completely by the patient's age (which, with the new variants, is rapidly changing, increasingly affecting younger patients) nor by symptoms and concomitant pathologies (which are no longer proving to be decisive in recent cases) in relation to medium-to-long term sequelae. In particular, the functions of the vascular endothelium and vascular lesions at the pre-capillary level represent the source of tissue hypoxia and other damage, resulting in the clinical evolution of COVID-19.

RESULTS

Keeping the patient at home with targeted therapeutic support, aimed at not worsening vascular endothelium damage with early and appropriate stimulation of endothelial cells, ameliorates the glycocalyx function and improves the prognosis and, in some circumstances, could be the best practice suitable for certain patients.

CONCLUSION

Clinical information thus far collected may be of immense value in developing a better understanding of the present pandemic and future occurrences regarding patient safety, pharmaceutical care and therapy liability.

Lab-on-a-Chip Immunoassay for Prediction of Severe COVID-19 Disease

Most people infected by the SARS-CoV-2 virus which causes COVID-19 disease experience mild or no symptoms. Severe forms of the disease are often marked by a hyper-inflammatory response known as a cytokine storm. Thus, biomarker tests which can identify these patients and place them on the appropriate treatment regime at the earliest possible phase would help to improve outcomes. Here we describe an automated microarray-based immunoassay using the Fraunhofer lab-on-a-chip platform for analysis of C-reactive protein due to its role in the hyper-inflammatory response.

Immunodominant T-cell epitopes from the SARS-CoV-2 spike antigen reveal robust pre-existing T-cell immunity in unexposed individuals

The COVID-19 pandemic has revealed a range of disease phenotypes in infected patients with asymptomatic, mild, or severe clinical outcomes, but the mechanisms that determine such variable outcomes remain unresolved. In this study, we identified immunodominant CD8 T-cell epitopes in the spike antigen using a novel TCR-binding algorithm. The predicted epitopes induced robust T-cell activation in unexposed donors demonstrating pre-existing CD4 and CD8 T-cell immunity to SARS-CoV-2 antigen. The T-cell reactivity to the predicted epitopes was higher than the Spike-S1 and S2 peptide pools in the unexposed donors. A key finding of our study is that pre-existing T-cell immunity to SARS-CoV-2 is contributed by TCRs that recognize common viral antigens such as Influenza and CMV, even though the viral epitopes lack sequence identity to the SARS-CoV-2 epitopes. This finding is in contrast to multiple published studies in which pre-existing T-cell immunity is suggested to arise from shared epitopes between SARS-CoV-2 and other common cold-causing coronaviruses. However, our findings suggest that SARS-CoV-2 reactive T-cells are likely to be present in many individuals because of prior exposure to flu and CMV viruses.

Antibody response to SARS-CoV-2 infection over six months among Nicaraguan outpatients

New information is emerging about SARS-CoV-2 epidemiology and immunity, but little of this information comes from low- and middle-income countries or from patients receiving care in the outpatient setting. The current study investigated the SARS-CoV-2 infection status and antibody responses in 157 patients seeking care for a respiratory disease suggestive of COVID-19 in private healthcare clinics during the first wave (June-October 2020) of infections in Nicaragua. We examined nasal swabs for the presence of viral RNA via RT-PCR and longitudinally collected sera for the changes in SARS-CoV-2 Spike antibody levels over six months. Among patients with confirmed SARS-CoV-2 infections, we evaluated if clinical symptoms were associated with age, hematological parameters and co-morbidities. The combination of PCR and paired serology identified 60 (38%) of the 157 outpatients as acute COVID-19. While both PCR and serology identified the majority (n = 38, 64%) of the acute infections, a notable number of outpatients were identified by RT-qPCR (n = 13, 22%) or by serology (n = 9, 14%) only. During the longitudinal study, we identified 6 new infections by serology among the 97 non-COVID-19 subjects. In conclusion, this study report that more than one third of the outpatients seeking care for acute respiratory disease during the first epidemic wave of SARS-CoV-2 in Nicaragua had an acute mild COVID-19 infection that correlate with prolonged humoral response. This immune response to the RBD antigen, more likely IgG dependent, significantly increased between the acute to convalescent and decay in the late convalescent but still remained seropositive.