anti sars cov 2 spike protein test results interpretation

11 Antibody tests may help identify past SARS-CoV-2 infection if performed two to four. After the first dose, NAb were detected in mice that received 1, 10, and 30g ChulaCov19 with corresponding GMTs of micro-VNT50 titer of 80, 368, and 735, respectively. 2c). Experiment 2: heterologous prime-boost study, mice were primed with 1/10 of the approved human dosage of CoronaVac or AZD1222 and boosted 4 weeks later with 5g of ChulaCov19. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This discovery may shed light on crucial aspects of SARS-CoV-2 infection, patient care methods, and future vaccine and antiviral development. In all past pandemics, as well as the ongoing one with COVID-19, access to effective vaccines in a timely manner and has been severely limited in these countries. The reaction was stopped by adding 50l/well of 0.5M sulfuric acid. n=5 per group for Experiment 1, 2 and 3. b Challenge study in K18-hACE2 transgenic mice, n=6 in vaccinated groups and n=5 in control (PBS-receiving) group. PubMed Jackson, L. A. et al. Results from antibody testing should not be used as the sole basis to diagnose or exclude SARS-CoV-2 infection or to inform infection status. The authors acknowledge all the members of the Chula VRC for their input and support. Vero E6, green monkey kidney epithelial cell line, was obtained from ATCC (Old Town Manassas, VA, USA). Limited and Short-Lasting Virus Neutralizing Titers Induced by Inactivated SARS-CoV-2 Vaccine. Statistical significance was determined by two-sided MannWhitney test. This elicited immunogenicity is significantly higher than those induced by homologous CoronaVac or AZD1222 vaccination. Proc Natl Acad Sci U S A 93, 41024107 (1996). Google Scholar. ChAdOx1 nCoV-19 vaccine prevents SARS-CoV-2 pneumonia in rhesus macaques. This observation correlates with that of a recent clinical study report53. So there is not enough data available to comment on the uptake of this therapy yet and raises the question in cases of previous infection or vaccination, the need to assess the SARS-CoV-2 antibody level for therapy decision making [1820]. It also can show how your body reacted to COVID-19 vaccines. Google Scholar. b heterologous prime/boost study; mice were primed with CoronaVac or AZD1222 vaccine and boosted with ChulaCov19 (5g). Alexander-Miller, M. A., Leggatt, G. R., Sarin, A. 7, eabi5246 (2021). This study complied with the World Medical Association Declaration of Helsinki regarding the ethical conduct of research involving human subjects. The aim was to assess the threshold of 264 binding antibody units (BAU)/ml using four different SARS-CoV-2 antibody assays (Abbott, Beckman, Roche, and Siemens) and to establish a new optimal threshold of protection for each of the four antibody assays. World Health Organization (2022). The reactions were then stopped with 50L of 0.16N sulfuric acid. In contrast, CoronaVac immunization showed the lowest T cells responses (42 SFC/106 splenocytes). Google Scholar. What are the benefits of exercise on cardiovascular health. This is consistent with a previous report46. Testing for SARS-CoV-2 Infection. Koonpaew, S. et al. This is especially true of the mRNA vaccines, and the approach has shown better results than homologous prime-boost with a non-mRNA-based vaccine51. In female BALB/c mice, ChulaCov19 at 0.2, 1, 10, and 30 g elicits robust neutralizing antibody (NAb) and T cell responses in a dose-dependent relationship. The National Library of Medicine is running a pilotto include preprints that result from research funded by NIH in PMC and PubMed. The Abbott AdviseDx SARS-CoV-2 IgG II immunoassay detects antibodies to the viral spike protein (S). Slides were then incubated with protease plus for 20min at 40C in a HybEZTM oven (ACD) and subsequently incubated with the SARS-CoV-2 specific probe for 2h at 40C in the HybEZTM oven. SARS-CoV-2 Antibodies (NCVIGG, NCVIGQ)[NCVIGB], The qualitative detection of anti-Nucleocapsid IgG (NCVIGG) and the quantitative detection of anti-Spike IgG (NCVIGQ) antibodies. SARS-CoV-2 neutralizing antibodies decline over one year and patients with severe COVID-19 pneumonia display a unique cytokine profile. Molecular-based testing is used to diagnose COVID-19, and serologic testing of antibodies specific to SARS-CoV-2 is used to detect past infection. While neurological signs have been documented in some, not all, coronavirus disease 2019 (COVID-19) patients, the precise mechanism by which viruses affect neuronal cells is still unknown and, thus, a subject of investigation. The S1 subunit substantially lowered the number of bursts per electrode, whereas the S2 subunit did not exhibit the same degree of reduction. In just over 2 years into the pandemic, more than 10 variants of the virus have been reported, of which, 5 variants, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B1.1.529) have been categorized by WHO as variants of concern (VOCs)7. Christina K. Psomas, Omicron stood out from other variants because it contained mutations that helped it evade immune cell protection. Lancet 396, 19791993 (2021). Agreements between antibody-binding assays and Genscript sVNT were performed using Cohens kappa, crude concordance rate, and area under curve (AUC). This is a surrogate marker indicative of vaccine effectiveness, or the sterilizing immunity as reported in the previous study27. PubMed PLoS One 16, e0249090 (2021). Frdrique Retornaz, Function of the expressed S protein was also confirmed as it could bind to hACE-2 similar to those of stabilized trimeric spike (Fig. Ying, B. et al. James Heyes, A. J., Kieu Mong, L. A. M., Alan, D. MARTIN. The SARS-CoV-2 Omicron variant emerged in late 2021 and spread quickly. Splenocytes were collected at 2 weeks after the second dose (Experiment 1 & 2). UW MedicineDepartment of Laboratory MedicineVirology- Covid Testing Lab1601 Lind Ave SWRenton, WA 980573356Tel: (206) 685-6656 opt 4. PN20-06). Statistical analysis was performed using GraphPad Prism 9.0 software (San Diego, CA, USA). The LNP- encapsulated mRNA were characterized for their size, polydispersity using a Zetasizer (Zetasizer Nano DS, Malvern, UK), encapsulation efficiency, and shipped on dry ice and stored at 80 oC until use. In conclusion, whether it is generally believed that a certain level of antibodies is necessary to confer protection against the virus, but the exact level required is not yet clear. Patrick Philibert, Therefore, the data indicated that the S1 subunit affected neurons only when the cells were exposed during the earliest stages of development. Available from: https://covid19.trackvaccines.org/agency/who (2022). Since the outbreak of COVID-19, the world has raced to understand and accurately diagnose infection caused by SARS-CoV-2. Comparative immunogenicity and reactogenicity of heterologous ChAdOx1-nCoV-19-priming and BNT162b2 or mRNA-1273-boosting with homologous COVID-19 vaccine regimens. Absorbance at 450nm was determined with a spectrophotometer. There were few limitations in this study. PubMed The information of SARS-CoV-2 isolates including, wild-type (Wuhan-Hu1), Alpha (B.1.1.7), Beta (B.1.351) and Delta (B.1.617.2) variants for micro-VNT50 assay performed at the Department of Microbiology, Faculty of Sciences, Mahidol University was described previously56,57. ChulaCov19 vaccination could provide 100% protection from severe clinical signs and mortality in mice. In brief, mouse splenocytes at 5105 cells/well were cultured with SARS-CoV-2 spike peptide pools spanning the entire sequence of spike protein, 25 peptides/pool (Mimotopes, Mulgrave, Victoria, Australia) at a final concentration of 2g/mL at 37C, 5% CO2 for 40h. Pools 15 and 610 corresponded to S1 and S2 regions of spike protein, respectively. Indeed, antibody therapy for pre-exposure prophylaxis (PrEP), may be efficient in preventing hospitalization in immunocompromised patients, regardless of the variant involved. Virus titers were quantified by RT-qPCR and by determined the log10TCID50 values. on this website is designed to support, not to replace the relationship Differences were considered significant at p<0.05 with exact p-values shown. Monovalent vs. bivalent vaccines Which is more effective against SARS-CoV-2? Med. Protection against WT (Wuhan-Hu1) viral challenge in K18-hACE2 transgenic mice mediated by ChulaCov19 was successfully demonstrated. For western blot analysis, cell culture supernatant was analyzed by 12% polyacrylamide gel then transferred onto nitrocellulose membrane. To address dose-response study of the ChulaCov19 and heterologous prime-boost responses with other approved COVID-19 vaccines, female BALB/c mice (Mus musculus), 4-6 weeks of age, (procured from Nomura Siam International, Bangkok, Thailand) were randomly divided into 5 mice/group for 3 sets of experiment. Each dot represents an individual animal. EBioMedicine 77, 103902 (2022). Statistical significance was set at P < 0.05. Follow-up testing with a molecular diagnostic should be considered to rule out infection in these individuals. Pairwise comparisons were performed using the nonparametric Wilcoxon test. In supernatant, we could detect both intact S and cleaved S1 and S2 (Fig. To obtain A recent randomized efficacy trial of the ChAdOx1 nCoV-19 (AZD1222) vaccine conducted in more than 8,500 patients in the United Kingdom, analyzed the antibody levels associated with protection against SARS-CoV-2 [7]. Viruses were propagated in Vero E6 cells to generate sufficient titers 100TCID50 for the micro-VNT50 assay. Stability: Sample stable off the clot, red blood cells, or separator gel for 7 days at 2-8C. Therefore, we suggest specific BAU/ml adjusted thresholds for the four commercial antibody assays (Abbott, Beckman, Roche, and Siemens), which can be used to guide the use of PreP in immunocompromised patients. 4c. T-cell responded to S1-pooled peptides much more common than to S2-pooled peptides. https://doi.org/10.1038/s41467-023-37795-0, DOI: https://doi.org/10.1038/s41467-023-37795-0. Establishment of an mRNA vaccine platform in low- and middle-income countries (LMICs) is important to enhance vaccine accessibility and ensure future pandemic preparedness. PubMed Central In the heterologous vs homologous prime/boost experiment (Experiment 2), homologous ChulaCov19 and homologous AZD1222 immunizations elicited comparable levels of S-specific IFN- positive T cells responses which was 2482 and 2210 SFC/106 splenocytes, respectively. They were widely available in these countries for approximately a year before being accessible on other continents. After SARS-CoV-2 challenge, there was no measurable decline in body weight among vaccinated groups. m8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p a8 0 H $g 3 @p 18n e>0> Wong, T. Y. et al. An, D. et al. COVID19 Vaccine Tracker [cited 2022 19 August]. Cells were then fixed with 4% paraformaldehyde for 30min at RT. The vaccine effectiveness is varied due to several factors such as the emergence of new variants, study population, and prevalence of the outbreak during the period the studies were conducted11,12,13. . Emerg Infect Dis 27, 31783180 (2021). Peletta, A. et al. ChulaCov19 significantly enhanced the magnitude of both NAb and T cell responses compared to homologous 2-dose regimens of either CoronaVac or AZD1222. The FFPE tissue slides were deparaffinized and treated with hydrogen peroxide (10min at room temperature) followed by target retrieval in 1X target retrieval solution in a steamer of at least 99C for 15min. Lipid nanoparticles). EP was also supported by Faculty of Medicine, Chulalongkorn University, grant No. b hACE-2 binding assay (merged): culture supernatant collected from ChulaCov19 transfected cells incubated with HEK293T- hACE-2 cells. The geometric mean titers (GMTs) of NAb against wild-type (WT, Wuhan-Hu1) virus are 1,280, 11,762, 54,047, and 62,084, respectively. Furthermore, the immunity in immunocompromised individuals may be less robust than in healthy individuals and may wane more quickly. 201 0 obj <>stream This candidate vaccine has now completed non-clinical toxicity and biodistribution studies and has entered Phase 1 and 2 human trials. Human codon-optimized sequences of the ectodomain of SARS-CoV-2 spike protein, amino acid position 1-1,210 (Wuhan Hu-1 complete genome, GenBank: MN908947.1, https://www.ncbi.nlm.nih.gov/nuccore/MN908947.1) was synthesized by GenScript, Piscataway, NJ, USA). In the control group, positive viral RNA staining was present in individual neurons of the olfactory bulb (4/4), epithelial cells of the nasal sinus (4/5), alveolar epithelial cells and macrophages in the lung (5/5), see Table1. Nat Immunol 21, 13271335 (2020). However, the slightly higher level compared to the 30-g group was not statistically significant. Her college project work based on The manifestations and causes of sickle cell anemia formed the stepping stone to a life-long fascination with human pathophysiology. The S protein facilitates virus attachment and entrance into the host cell. 6b, c, Table1). : data collection, A.T., A.J., K.R., K.P., T.P., M.R., D.W., and K.R. All p values <0.05 were defined as statistically significant. Immunofluorescent results mostly correlate with PCR data. Adv. Source data are provided as a Source Data file. Experiment 2: c micro-VNT50 titers against WT (Wuhan-Hu1), Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.2) live-virus at two weeks after receiving various homologous or heterologous prime/boost regimens. d psVNT50 NAb titer results at two weeks after the second dose in various prime/boost regimens againt Omicron BA.1 and BA.4/5 subvariants. Identifying a specific threshold level of SARS-CoV-2 antibodies that confers protection in immunocompromised patients has been very challenging. Ann Intern Med 174, 286287 (2021). Moreover, the tissue slides were examined unblind. The mid-point titers were determined in duplicate assays from 5 mice in each group. CK, EP and KR were funded by the National Vaccine Institute (NVI), grant No. Optimal cutoffs for distinguishing positivity were calculated using logistic regression on Genscript sVNT binary results (negative/positive), prior to the Youden index maximization approach on receiver operating characteristic curve results. 4c). 2023. Another limitation was the lack of an external cohort to validate the suggested thresholds. The remaining authors declare no competing interests. 3b). COVID-19 antibody testing is a blood test. Additional group (Experiment 3) immunized with 5g of ChulaCov19 was included for evaluation of NAb durability as measured at week 18 (15 weeks after received the 2nd dose) and the boosting effect of 3rd ChulaCov19 dose administered at week 20. This initiative is ready to be part of the global effort to make mRNA vaccines more quickly and widely available when facing new variants or the next pandemic. Samples from 69 patients were included in this study. In the clinical setting, >8 weeks interval for AZD1222 was recommended to maximize the vaccine efficacy52. WIPO (2020). 4e). Rotshild, V., Hirsh-Raccah, B., Miskin, I., Muszkat, M. & Matok, I. WHO. Philippe Cartlamy, Cannabis users with a genetic predisposition to schizophrenia more likely to experience psychotic symptoms. WW is an employee of BioNet-Asia, Co. Ltd. We have disclosed those interests fully to their affiliations, and we have in place an approved plan for managing any potential conflicts arising from licensing of the patents. Secreted mouse IFN- was captured by anti-mouse IFN- (AN18) monoclonal antibody at dilution of 1:2,500 (Mabtech, Nacka Strand, Sweden) precoated on 96-well nitrocellulose membrane plates (Merk Millipore, Darmstadt, Germany). Nat Commun 12, 372 (2021). Feikin, D.R. No positive detection of viral RNA was present in the 10g group of animals analyzed by ISH. Available from: https://www.who.int/initiatives/the-mrna-vaccine-technology-transfer-hub (2022). Nucleoside-modified mRNA was produced by in vitro transcription (IVT) by substitution of uridine triphosphate (UTP) with N1-methylpseudouridine (m1) triphosphate (TriLink, Biotechnologies, San Diego, CA, USA), detailed elsewhere58. By 18th August 2022, almost 600 million confirmed cases were caused by multiple VOCs and almost 6.5 million deaths were reported9. e0281257. Evaluation of COVID-19 vaccine effectiveness in a changing landscape of COVID-19 epidemiology and vaccination: interim guidance, 1 October 2022: second addendum to Evaluation of COVID-19 vaccine effectiveness: interim guidance. Lancet 396, 467478 (2020). Route to Eastlake Virology (EVIR rack 81). endobj x2- p` ` \0`0e`X{StAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA^@%&D7(mylkv The NT50 titer decrease found in our study was similar to those of other approved vaccines as the titers against BA.1 and BA.4/5 decreased by more than 8-10 folds when compared to the WT virus46,47,48. As the Omicron subvariant BA.4/5 is currently spreading worldwide, we have also assessed cross-neutralization and found that the NAb GMT measured by psVNT50 against BA.4/5 in homologous ChulaCov19 vaccination or heterologous boosted with ChulaCov19 groups were significantly better than either of the CoronaVac or AZD1222 homologous vaccination (Fig. In addition, AZD1222 was also showed to be effective in clinical trials39,40. This neutralization antibody detection kit is designed to mimic the virus-host interaction utilizing recombinant RBD of the SARS-CoV-2 spike protein to detect antibodies that block the RBD binding to the hACE2 receptor. Detailed amino sequence was shown in Supplementary File1. Science 377, 890894 (2022). The authors would like to thanks Dr.Navapon Techakriengkrai, Faculty of Veterinary Science, Chulalongkorn University for providing HEK293T-hACE-2 cells. PubMed Central Zheng, C. et al. On day zero, neurons obtained from newborn P1 mice were treated with recombinant SARS-CoV-2 S protein and S1 and S2 S2 subunits. Post-translational modifications were also similar to those observed on SARS-CoV-241. Interim statement on the use of additional booster doses of Emergency Use Listed mRNA vaccines against COVID-19). The micro-VNT50 titers was calculated as the reciprocal serum dilution that neutralized 50% of virus observed in virus control wells using probit analysis, SPSS program71. Agreement between antibody binding assays and Genscript sVNT positive and negative results according to the reference cutoff (264 BAU/ml). Previous specific optimal cutoffs fitted perfectly to patients with incomplete vaccination: a perfect agreement was observed between Genscript sVNT and each antibody binding assays among these patients (results not shown). Methods Protoc. Among the recently approved vaccines, mRNA modality seems to be the most efficacious as it induces high levels of desired immune responses and protects from severe symptoms16,17. Five micrograms of ChulaCov19 was selected as we aimed to standardize the dosage to 1/10 of human dose for all vaccines (50g per dose of ChulaCov19 was used in phase II studies, Clinical Trial Identifiers: NCT05231369 and NCT05605470)63,64. Based on these studies, a threshold of 264 BAU/ml antibody was used as a recommendation for the use of PrEP in SARS-CoV-2 in France, and extrapolated to immunocompromised patients [9]. Unfortunately, it has also been proven that vaccine efficacy decreases over time14. 2c). Additional quality control to ensure the absence of double-stranded RNA (dsRNA) and endotoxin contamination prior to encapsulation into lipid nanoparticles (LNPs) were performed as described previously60. The bands corresponding to S1, S2 and intact S (S0) were detected. a Experiment 1: mice were immunized twice intramuscularly (IM) with a 3-week interval with various dosages of ChulaCov19 at 0.2, 1, 10 and 30g. Notably, SARS-CoV-2 RNA measured by ISH was undetected in lung tissues in mice vaccinated with ChulaCov19 at either 1 or 10 g dose. Previous study by Eichinger KM, et al. At this time-point, 10g dosed mice induced significantly higher in GMTs of micro-VNT50 titers than 1g dosed mice (p=0.0065). The most effective COVID-19 vaccines are mRNA-based and were first approved in the United Kingdom, the United States, and Europe. a Kinetics of total IgG at 2 weeks after receiving 1 or 2 doses of 0.2, 1, 10, and 30g of ChulaCov19. endstream Comparisons of the data between groups were made using non-parametric tests (MannWhitney test). 200 0 obj <>]/Filter/FlateDecode/BitsPerComponent 8/Length 2211/Height 275>>stream For example, the psVNT-50 against BA.1 in the CoronaVac-prime/ChulaCov19-boost group (psVNT-50 GMT=875) was significantly higher (p<0.01) than homologous CoronaVac (psVNT-50 GMT=5.1) and homologous AZD1222 (psVNT-50 GMT=2.7) groups. Labcorp offers both semi-quantitative and qualitative options for testing for spike protein antibodies. Ramasamy, M. N. et al. A. https://ClinicalTrials.gov/show/NCT05605470 (2022). Bhavana Kunkalikar is a medical writer based in Goa, India. The results demonstrated that, at least up to 12 months, only minor changes were observed when the particles were stored in 75 oC (Supplementary Table1) and were still within the acceptable criteria. The S1 subunit interacts with the angiotensin-converting enzyme 2 (ACE2) receptor present in the intestinal and lung cells. Figures were created with BioRender.com. A Single-Cycle Influenza A Virus-Based SARS-CoV-2 Vaccine Elicits Potent Immune Responses in a Mouse Model. This result implied that the decrease in Nab titers against BA.4/5 may be improved with higher mRNA vaccine doses. In mice, ChulaCov19 was highly immunogenic as a booster in settings primed with either inactivated or viral vector vaccine. Bar-On, L. et al. 4a). We use cookies to enhance your experience. The Wilcoxon test for pairwise comparisons yielded P < 0.0001 for all comparisons. Nat Commun 13, 4710 (2022). Is there an association between COVID-19 and the risk of developing an autoimmune disease? Medicines and Healthcare products Regulatory Agency (2022). Blood was collected at wk0, wk2, wk3, wk4+6 and wk5+6 days for antibody kinetic analysis (Fig. 1a). The results resembled those observed in the panel that used a commercial recombinant S-trimer instead of transfected supernatant. Immunogenicity and protective efficacy of SARS-CoV-2 mRNA vaccine encoding secreted non-stabilized spike in female mice, https://doi.org/10.1038/s41467-023-37795-0. Homologouse prime/boost results of each vaccine were included. Pathogenesis of SARS-CoV-2 in Transgenic Mice Expressing Human Angiotensin-Converting Enzyme 2. Vaccine inequity issue remains a major global challenge. Kunkalikar, Bhavana. However, further beneficial evaluation on the use of native-like S protein structure requires in-depth analysis in clinical settings especially in immune elicitation characteristics. Mice were bled at 2 weeks after each dose and antibody responses were measured by ELISA and/or neutralization assays. The team assessed the data using an algorithm devised in-house. N Engl J Med 383, 19201931 (2020). Some tests provide results rapidly (within minutes); others require 1-3 days for processing. The interpretation of the calculated ratios was performed as manufacturer's recommendation. J Control Release 217, 345351 (2015). Note: tissues from 3/5 animals in control group were collected at day 5. In this interview conducted at Pittcon 2023 in Philadelphia, Pennsylvania, we spoke to Dr. Chad Merkin, Director of the International Institute for Nanotechnology, about his work developing next-generation nanomaterials for medical applications. Hence, in this study, although the NAb was displayed in a dose-dependent fashion, in-depth analysis of T cell quality induced by different vaccine dosage is also needed to investigate the controversy of viremia after challenge. In Experiment 3, the durability of NAb induced by ChulaCov19 was monitored until week 18 (15 weeks after the 2nd dose). Kappa increased to 0.76 for the Abbott assay (0.04 units increase) and to 0.71 for the Roche assay (0.19-unit increase). The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical. Article In the homologous prime/boost of these 2 approved vaccines groups, each was given at four weeks interval. The plasmid was propagated in E. coli (Stbl3, Invitrogen, Carlsbad, CA, USA) and extracted by EndoFree Giga Kit (Qiagen, Hilden, Germany). There were no anamnestic responses (four-fold increase on micro-VNT50 titers) in all vaccinated groups 6 days after the challenge, whereas one mouse in the control group developed a low micro-VNT50 titer at 40. a Kinetic response of micro-VNT50 titer after ChulaCov19 immunization and after challenge. b Body-weight values with SD are presented as a percentage of initial body weight before challenge (Day 0) through Day 6 post-challenge. Boxplots for each antibody binding assay according to Genscript sVNT positive and negative results. Infect Dis Poverty 11, 53 (2022). plasma, or dried blood spot (DBS) using the S1 domain of the recombinant SARS-CoV-2 spike protein expressed in the HEK 293 human cell line . Characteristics like the number of bursts per electrode, their duration, frequency, and the number of spikes per burst according to the treatment condition were also quantified. In the immunogenicity dose-response and prime/boost studies (Experiment 1 and 2), NAb measurement was carried out as previously described56,68 based on live-virus micro-VNT50 against WT (Wuhan-Hu1), Alpha (B.1.1.7), Beta (B.1.351), Delta (B1.617.2) variants in VERO E6 cells with positive cut-off of 1:20. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. By using immunofluorescent assay, employing RBD-, S1-, S2-specific antibodies or PCS, the S proteins were observed within the cytoplasm of transfected cells while untransfected cells were negative for fluorescent signal (Fig.
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