Sensitive and specific serological ELISA for the detection of SARS-CoV-2 infections.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has triggered the worldwide coronavirus disease 2019 (COVID-19) pandemic. Serological assays for the detection of SARS-CoV-2 infections are important to understand the immune response in patients and to obtain epidemiological data about the number of infected people, especially to identify asymptomatic persons not aware of a past infection. METHODS: We recombinantly produced SARS-CoV-2 nucleocapsid (N)-protein in Escherichia coli. We used the purified protein to develop an indirect enzyme-linked immunosorbent assay (ELISA) for the detection of SARS-CoV-2 specific antibodies. This ELISA method was optimized and validated with serum samples collected from 113 patients with RT-PCR-confirmed SARS-CoV-2 infections including hospitalized COVID-19 patients and 1500 control sera mostly collected before 2015 with different clinical background. RESULTS: The optimized N-protein-ELISA provided a sensitivity of 89.7% (n = 68) for samples collected from patients with confirmed SARS-CoV-2 infections and mild to severe symptoms more than 14 days after symptom onset or a positive PCR test. The antibody levels remained low for serum samples collected in the first six days (n = 23) and increased in the second week (n = 22) post symptom onset or PCR confirmation. At this early phase, the ELISA provided a sensitivity of 39.1% and 86.4%, respectively, reflecting the time of an IgG immune response against pathogens. The assay specificity was 99.3% (n = 1500; 95% CI 0.995-0.999). Serum samples from persons with confirmed antibody titers against human immunodeficiency viruses 1/2, parvovirus B19, hepatitis A/B virus, cytomegalovirus, Epstein Barr virus, and herpes simplex virus were tested negative. CONCLUSIONS: We conclude that the N-protein-based ELISA developed here is well suited for the sensitive and specific serological detection of SARS-CoV-2 specific IgG antibodies in human serum for symptomatic infections. It may also prove useful to identify previous SARS-CoV-2 infections in vaccinated people, as all currently approved vaccines rely on the SARS-CoV-2 spike (S-) protein.

Telomere length differences between subcutaneous and visceral adipose tissue in humans.

Adipocyte hypertrophy and hyperplasia have been shown to be associated with shorter telomere length, which may reflect aging, altered cell proliferation and adipose tissue (AT) dysfunction. In individuals with obesity, differences in fat distribution and AT cellular composition may contribute to obesity related metabolic diseases. Here, we tested the hypotheses that telomere lengths (TL) are different between: (1) abdominal subcutaneous and omental fat depots, (2) superficial and deep abdominal subcutaneous AT (SAT), and (3) adipocytes and cells of the stromal vascular fraction (SVF). We further asked whether AT TL is related to age, anthropometric and metabolic traits. TL was analyzed by quantitative PCR in total human genomic DNA isolated from paired subcutaneous and visceral AT of 47 lean and 50 obese individuals. In subgroups, we analyzed TL in isolated small and large adipocytes and SVF cells. We find significantly shorter TL in subcutaneous compared to visceral AT (P < 0.001) which is consistent in men and subgroups of lean and obese, and individuals with or without type 2 diabetes (T2D). Shorter TL in SAT is entirely due to shorter TL in the SVF compared to visceral AT (P < 0.01). SAT TL is most strongly correlated with age (r = -0.205, P < 0.05) and independently of age with HbA1c (r = -0.5, P < 0.05). We found significant TL differences between superficial SAT of lean and obese as well as between individuals with our without T2D, but not between the two layers of SAT. Our data indicate that fat depot differences in TL mainly reflect shorter TL of SVF cells. In addition, we found an age and BMI-independent relationship between shorter TL and HbA1c suggesting that chronic hyperglycemia may impair the regenerative capacity of AT more strongly than obesity alone.

Influence of Mutations and N-Glycosylation Sites in the Receptor-Binding Domain (RBD) and the Membrane Protein of SARS-CoV-2 Variants of Concern on Antibody Binding in ELISA.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect human cells by first attaching to the ACE-2 receptor via its receptor-binding domain (RBD) in the spike protein. Here, we report the influence of N-glycosylation sites of the RBD and the membrane (M) protein on IgG antibody binding in serum samples from patients infected with the original SARS-CoV-2 strain in Germany. The RBDs of the wildtype, alpha, beta, gamma, and kappa variants expressed in HEK293S GnTI- cells were all N-glycosylated at Asn331, Asn334, Asn343, and Asn360 or Asn370, whereas the M-protein was glycosylated at Asn5. An ELISA using a coated RBD and probed with anti-RBD IgG antibodies gave a sensitivity of 96.3% and a specificity of 100% for the wildtype RBD, while the sensitivity decreased by 5% to 10% for the variants of concern, essentially in the order of appearance. Deglycosylation of the wildtype RBD strongly reduced antibody recognition by ~20%, considering the mean of the absorbances recorded for the ELISA. This effect was even stronger for the unglycosylated RBD expressed in Escherichia coli, suggesting structural changes affecting epitope recognition. Interestingly, the N-glycosylated M-protein expressed in HEK293S GnTI- cells gave good sensitivity (95%), which also decreased to 65% after deglycosylation, and selectivity (100%). In conclusion, N-glycosylation of the M-protein, the RBD, and most likely the spike protein are important for proper antibody binding and immunological assays, whereas the type of N-glycosylation is less relevant.

Transcriptional regulation of the GLAST/EAAT-1 gene in rat and man.

Various acute and chronic brain diseases result in disturbed expression of the glial glutamate transporters, GLAST/EAAT-1 and GLT-1/EAAT-2, and subsequent secondary neuronal cell death. The idea that glutamate-induced brain damage can be prevented by restoring glutamate homeostasis in the injured brain, focussed previous efforts on identifying the network controlling astrocytic glutamate transport. Since most of this work was performed with rat astrocytes, we now sought to compare the transcriptional regulation of the GLAST/EAAT-1 gene in rat and man. Reporter gene assay demonstrated that the human GLAST/EAAT-1 promoter comprises the 2.3 kb region immediately flanking the 5'-end of the human GLAST/EAAT-1 gene. Cloning of the previously unknown promoter of rat GLAST/EAAT-1 gene demonstrated maximal reporter gene activity with a sequence comprising the 1.5 kb region flanking the 5'-end of the gene as well as non-coding exon 1, and intron 1-2. Although the promoter regions from both species lacked sequence homology, they contained numerous identical consensus motifs. In human promoter constructs, dbcAMP, PACAP, EGF, and TGFα, which represent potent stimulators of endogenous GLAST/EAAT-1 expression, only further increased reporter gene activity in the presence of the GLAST/EAAT-1 3'-UTR. By contrast, the rat GLAST/EAAT-1 3'-UTR only mediated the stimulatory increases of dbcAMP. Moreover, the GLAST/EAAT-1 3'-UTR repressed constitutive GLAST/EAAT-1 expression in man, but enhanced GLAST/EAAT-1 transcription in rat. Together, our findings suggest the existence of close functional similarities of the GLAST/EAAT-1 promoter regions in man and rat and further point to a species-specific function of the GLAST/EAAT-1 3'-UTR in constitutive and regulated GLAST/EAAT-1 expression.

Immunogenetic Predisposition to SARS-CoV-2 Infection.

Herein, we included 527 individuals from two Hospitals, Chemnitz and University-Hospital Leipzig. In total, 199 were negative for PCR and 328 were positive upon first admission. We used next generation sequencing for HLA-A, B, C, DRB1, DRB345, DQA1, DQB1, DPA1, and DPB1, and in some cases, HLA-E, F, G, and H. Furthermore, we molecularly defined 22 blood group systems comprising 26 genes and 5 platelet antigen genes. We observed a significant enrichment of homozygosity for DQA/DQB in the positive group. Within the negative subjects, HLA-B*57:01, HLA-B*55:01, DRB1*13:01, and DRB1*01:01 were enriched, and in the positive group, homozygosity for DQA/DQB, DRB1*09:01, and DRB1*15:01 was observed. DQA1*01:01, DQA1*02:01, and DQA1*01:03 were enriched in the negative group. HLA-DQB1*06:02 was enriched in the positive group, and HLA-DQB1*05:01 and HLA-DQB1*06:03 were enriched in the negative group. For the blood group systems MNS, RH, LE, FY, JK, YT, DO, and KN, enrichment was seen in both groups, depending on the antigen under observation. Homozygosity for D-positive RHD alleles, as well as the phenotypes M-N+ of the MNS blood group system and Yk(a-) of the KN system, were enriched in the positive group. All of these significances disappeared upon correction. Subjects who carried homozygous HPA-1a were more frequent in the negative group, contrasting with the finding that HPA-1ab was enriched in the positive group.

Evaluation of S- and M-Proteins Expressed in Escherichia coli and HEK Cells for Serological Detection of Antibodies in Response to SARS-CoV-2 Infections and mRNA-Based Vaccinations.

This study investigated the IgG and IgA antibody response against recombinant S1 and receptor binding domains (RBD) of the spike (S-) protein and the membrane (M-) protein using a set of 115 serum samples collected from patients infected with SARS-CoV-2 in Germany before April 2021 using protein and peptide ELISA. As S1- and RBD-proteins expressed in Escherichia coli provided poor sensitivities in ELISA, they were replaced by proteins expressed in HEK cells. The RBD-ELISA provided a sensitivity of 90.6% (N = 85) for samples collected from patients with confirmed SARS-CoV-2 infections more than 14 days after symptom onset or a positive PCR test. In population-based controls, the specificity was 97.9% (N = 94). In contrast, the sensitivities were only 41.2% and 72.6% for M- and N-proteins, respectively, while the specificities were 88.5% and 100%, respectively. Considering also 20 samples collected during the first two weeks of symptom onset or PCR confirmation, the sensitivity of RBD- and N-protein ELISA decreased to 82.6% and 72.6%, respectively. The combination of two data sets, i.e., N- and RBD-, N- and M-, or RBD- and M-proteins increased the sensitivity to 85.8%, 77.9%, and 87.8%, respectively. Peptide mapping mostly confirmed epitopes previously reported for S1- and M-proteins, but they were only recognized by a few samples already tested positive in the corresponding protein ELISA indicating that peptide-based assays will not improve the diagnostic sensitivity.

Regional responsibility and coordination of appropriate inpatient care capacities for patients with COVID-19 - the German DISPENSE model.

As of late 2019, the COVID-19 pandemic has been a challenge to health care systems worldwide. Rapidly rising local COVID-19 incidence rates, result in demand for high hospital and intensive care bed capacities on short notice. A detailed up-to-date regional surveillance of the dynamics of the pandemic, precise prediction of required inpatient capacities of care as well as a centralized coordination of the distribution of regional patient fluxes is needed to ensure optimal patient care. In March 2020, the German federal state of Saxony established three COVID-19 coordination centers located at each of its maximum care hospitals, namely the University Hospitals Dresden and Leipzig and the hospital Chemnitz. Each center has coordinated inpatient care facilities for the three regions East, Northwest and Southwest Saxony with 36, 18 and 29 hospital sites, respectively. Fed by daily data flows from local public health authorities capturing the dynamics of the pandemic as well as daily reports on regional inpatient care capacities, we established the information and prognosis tool DISPENSE. It provides a regional overview of the current pandemic situation combined with daily prognoses for up to seven days as well as outlooks for up to 14 days of bed requirements. The prognosis precision varies from 21% and 38% to 12% and 15% relative errors in normal ward and ICU bed demand, respectively, depending on the considered time period. The deployment of DISPENSE has had a major positive impact to stay alert for the second wave of the COVID-19 pandemic and to allocate resources as needed. The application of a mathematical model to forecast required bed capacities enabled concerted actions for patient allocation and strategic planning. The ad-hoc implementation of these tools substantiates the need of a detailed data basis that enables appropriate responses, both on regional scales in terms of clinic resource planning and on larger scales concerning political reactions to pandemic situations.

Sequences of the non-coding RNA, NTAB, are contained within the 3'-UTR of human and rat EAAT2/GLT-1 transcripts and act as transcriptional enhancers.

In the CNS, extracellular glutamate is predominantly cleared by astroglial cells through the high-affinity glutamate transporter subtype, EAAT2/GLT-1. Expression of EAAT2/GLT-1 is perturbed in various acute and chronic brain diseases eventually allowing for the onset of neurotoxic extracellular glutamate concentrations and subsequent excitotoxic neuronal cell death. The idea that glutamate-induced brain damage could be prevented by restoring glutamate homeostasis in the injured brain, spurred considerable interest in identifying the mechanisms controlling EAAT2/GLT-1 expression. Since to date most of this study was done with rat astrocytes, an emerging issue is to whether these findings would also apply to humans. While so far it is known that the promoter region of the EAAT2/GLT-1 gene is strikingly similar in rat and man, little information is available on the function of the EAAT2/GLT-1 3'-UTR in the control of EAAT2/GLT-1 expression in general as well as across both species. We now report on the presence of a homologous sequence within the 3'-UTR of the human and rat EAAT2/GLT-1 gene which we identified as a partial sequence of the putative non-coding RNA, Ntab. We further demonstrate that fragments of Ntab act as enhancers of EAAT2/GLT-1 transcription. Finally, we unravel that partial Ntab sequences are selectively present in the vicinity of the EAAT2/GLT-1 gene in several other mammalians, implying a conserved function of this sequence in the vertebrate CNS.

Direct evidence of brown adipocytes in different fat depots in children.

Recent studies suggested the persistence of brown adipocytes in adult humans, as opposed to being exclusively present in infancy. In this study, we investigated the presence of brown-like adipocytes in adipose tissue (AT) samples of children and adolescents aged 0 to 18 years and evaluated the association with age, location, and obesity. For this, we analysed AT samples from 131 children and 23 adults by histological, immunohistochemical and expression analyses. We detected brown-like and UCP1 positive adipocytes in 10.3% of 87 lean children (aged 0.3 to 10.7 years) and in one overweight infant, whereas we did not find brown adipocytes in obese children or adults. In our samples, the brown-like adipocytes were interspersed within white AT of perirenal, visceral and also subcutaneous depots. Samples with brown-like adipocytes showed an increased expression of UCP1 (>200fold), PRDM16 (2.8fold), PGC1α and CIDEA while other brown/beige selective markers, such as PAT2, P2RX5, ZIC1, LHX8, TMEM26, HOXC9 and TBX1 were not significantly different between UCP1 positive and negative samples. We identified a positive correlation between UCP1 and PRDM16 within UCP1 positive samples, but not with any other brown/beige marker. In addition, we observed significantly increased PRDM16 and PAT2 expression in subcutaneous and visceral AT samples with high UCP1 expression in adults. Our data indicate that brown-like adipocytes are present well beyond infancy in subcutaneous depots of non-obese children. The presence was not restricted to typical perirenal locations, but they were also interspersed within WAT of visceral and subcutaneous depots.

InterACTIV: an exploratory study of the use of a game console to promote physical activation of hospitalized adult patients with cancer.

PURPOSE/OBJECTIVES: To explore the application of the Nintendo Wii game console to motivate hospitalized adult patients with cancer to be physically active during treatment periods. DESIGN: An exploratory study with a mixed-method approach, including descriptive statistics and Mayring's qualitative data evaluation method. SETTING: The Department of Radiation Oncology at the University Hospital in Halle (Saale) in Germany. SAMPLE: Convenience sample of 7 adult inpatients. METHODS: All patients received physical training for five days for 30 minutes per day with Nintendo Wii. After the last training session, patients were interviewed using a semistructured guideline. MAIN RESEARCH VARIABLES: Applicability of a motion-activated game console during inpatient treatment periods, patients' distraction from the hospital environment. FINDINGS: In general, the use of a motion-activated game console in a hospital environment was evaluated positively. Participants showed a high degree of acceptance using this kind of physical activity. Because of the Nintendo Wii, the majority of individuals felt stimulated to become physically active during hospitalization. In addition, all patients lost time awareness and felt distracted from the daily hospital routine. A majority of the patients reported an improved mood state from the game sessions. CONCLUSIONS: The results indicate that a motion-activated game console could be useful to motivate adult patients with cancer to be physically active during hospitalization. IMPLICATIONS FOR NURSING: Nurses can recommend the use of game consoles such as the Nintendo Wii for physical exercise; in addition, the motivational effects of playing motion-activated game consoles might be particularly helpful for patients with cancer-related fatigue to overcome barriers and begin exercise.