Detection Of IgG Research Articles

Assessment of SARS-CoV-2 IgG and IgM antibody detection with a lateral flow immunoassay test

The dramatic impact of SARS-CoV-2 infection on the worldwide public health has elicited the rapid assessment of molecular and serological diagnostic methods. Notwithstanding the diagnosis of SARS-CoV-2 infection is based on molecular biology approaches including multiplex or singleplex real time RT-PCR, there is a real need for affordable and rapid serological methods to support diagnostics, and surveillance of infection spreading. In this study, we performed a diagnostic accuracy analysis of COVID-19 IgG/IgM rapid test cassette lateral flow immunoassay test (LFIA) assay. To do so, we analyzed different cohorts of blood samples obtained from 151 SARS-CoV-2 RT-PCR assay positive patients (group 1) and 51 SARS-CoV-2 RT-PCR assay negative patients (group 2) in terms of sensitivity, specificity, PPV, NPV and likelihood ratios. In addition, we challenged LFIA with plasma from 99 patients stored during 2015–2017 period. Our results showed that this LFIA detected SARS-CoV-2 IgM and/or IgG in 103 out of 151 (68.21%) samples of group 1, whereas no IgM and/or IgG detection was displayed both in the group 2 and in pre-pandemic samples. Interestingly, IgM and/or IgG positivity was detected in 86 out of 94 (91.49%) group 1 samples collected after 10 days from symptoms onset whereas only 17 out of 57 of group 1 samples obtained before day 10 were positive to SARS-CoV-2 specific antibodies. We also compared the performance of this LFIA test with respect to other four different LFIA assays in 40 serum samples from multiplex RT-PCR positive individuals. Within the limits of the study size, the results demonstrated that COVID-19 IgG/IgM rapid test cassette LFIA assay displayed valid performance in IgM and IgG detection when compared with the other four LFIA assays.Hence, this approach might be considered as an alternative point-of-care procedure for SARS-CoV-2 serological investigation.

OAB-048: Suboptimal humoral immune response to SARS-CoV-2 mRNA vaccination in myeloma patients is associated with anti-CD38 mAb and BCMA-targeted treatment

BackgroundMultiple myeloma (MM) patients are immunocompromised due to defects in humoral/cellular immunity and immunosuppressive therapy. Reports indicate that the antibody (Ab) response in MM after 1 dose of SARS-CoV-2 RNA vaccine is attenuated. Vaccine response kinetics in patients with prior COVID-19 and impact of treatment remain unknown.MethodsWe analyzed SARS-CoV-2 spike-binding (anti-S) IgG level in 320 MM patients receiving COVID-19 vaccination. Blood and saliva were taken at multiple time points. 69 age-matched healthcare workers were used as controls.ResultsThe 320 MM patients (median age 68 years) received two-dose mRNA vaccines (69.1% BNT162b2, 27.2% mRNA-1273). Median time to diagnosis was 60 months with a median of 2 prior treatment lines (range 0-16). We included 23 patients with smoldering MM. 59 patients (18.4%) were not on active treatment; 148 (43.8%) received anti-CD38 mAb-containing treatment and 36 (11.3%) were on BCMA-targeted therapy. 131 patients (40.9%) exhibited a complete response at last evaluation. 260 patients (81.3%) had anti-S IgG measured >10 days after the second vaccine (median 51 days). Of these, 84.2% mounted measurable anti-S IgG levels (median 149 AU/mL). In the control group, Ab levels were significantly higher (median 300 AU/mL). Ab levels in the 38 vaccinated MM patients with prior COVID-19 were 10-fold higher than those of patients without prior COVID-19 (median 801 vs 69 AU/mL, p<0.001). MM patients on active treatment had lower anti-S IgG levels (p=0.004) compared to patients not on therapy (median 70 vs 183 AU/mL). Notably, 41 patients (15.8%) failed to develop detectable anti-S IgG: 24/41 (58.5%) were on anti-CD38 mAb, 13/41 (31.7%) on anti-BCMA bispecific Ab therapy and 4/41 (9.8%) >3 months after CAR T. Multivariate analysis (corrected for age, vaccine type, lines of treatment, time since diagnosis, response status and lymphopenia) confirmed that anti-CD38-containing (p=0.005) and BCMA-targeted treatment (p<0.001) are associated with not developing detectable anti-S IgG. Clinical relevance is emphasized by 10 cases of COVID-19 after 1 (n=7) or 2 vaccine doses (n=3, all without anti-S IgG) with 1 patient passing due to respiratory failure.ConclusionMM patients mount a suboptimal IgG response after SARS-CoV-2 vaccination with 15.8% developing no detectable anti-S IgG. Ongoing analyses will show kinetics of patients with low-normal Ab levels in comparison to healthy controls. SARS-CoV-2-specific T cell responses and extensive immunophenotyping of >40 patients in the context of vaccination will be reported at the meeting. Immediate implications are the continuation of non-pharmacological interventions, e.g. masking and social distancing, for vulnerable patients. The findings underscore a need for serological monitoring of MM patients following COVID-19 vaccination and for clinical trials assessing use of prophylactic strategies or studies exploring additional immunization strategies.

VACCINATED WITH A TWIST: BREAKTHROUGH COVID-19 IN AN IMMUNOCOMPROMISED PATIENT

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: With ongoing efforts to vaccinate the public against SARS-CoV2, there have been reports of breakthrough COVID-19 cases. We report a case of an immunocompromised patient who was infected despite being fully vaccinated. CASE PRESENTATION: 63-year-old female with COPD, rheumatoid arthritis on abatacept, prednisone, & methotrexate (MTX), and Sweet syndrome presented to the ED with acute non-exertional chest pain, palpitations, and dyspnea at rest. She denied fevers or chills but reported diarrhea and vomiting. She had no history of or exposure to COVID-19 and had completed her 2-dose mRNA SARS-CoV-2 vaccination 45 days prior. On presentation she was in respiratory distress, hypotensive, tachycardic, and tachypneic. She was saturating at 86% on room air, requiring supplemental O2. Physical exam was significant for scattered bilateral wheezes. CBC showed no leukocytosis. CRP was elevated. Lactic acid, ferritin and LDH were within normal limits. D-dimer was higher than the age-adjusted cutoff;CTA of the chest revealed no PE but showed bilateral ground glass opacities with consolidations. She tested positive for SARS-CoV-2. She was admitted for severe sepsis from COVID-19 pneumonitis and started on dexamethasone and remdesivir. SARS-CoV-2 IgG antibodies were positive. Given her immunocompromised status, bronchoscopy with BAL was performed and revealed copious thick secretions. Gram stain and bronchial brushings were negative for bacterial etiologies. Lavage culture was positive for aspergillus antigen and cytology revealed markedly enlarged reactive cells. Galactomannan serum antigen was positive. She was discharged on day 9 with a prolonged course of voriconazole. She had residual dyspnea on exertion but did not require supplemental O2. A nasal swab to test for variant strains was still pending. DISCUSSION: The COVID vaccine proved effective in preventing severe COVID-19 infections but trials excluded immunocompromised patients. This case of infection despite vaccination and detectable IgG titers reveals suboptimal protection. From data on pre-existing vaccines in immunocompromised patients, MTX is known to reduce immunogenicity. Our patient remained on immunosuppressants after vaccination, which may have contributed to her subsequent viral and fungal infections. Rheumatology guidelines suggest holding MTX for one to two weeks after vaccination to improve vaccine response. Employing this strategy will maximize immunogenicity against SARS-CoV-2 in immunocompromised patients. CONCLUSIONS: The American College of Rheumatology recommends vaccinating patients with rheumatological conditions against SARS-CoV-2. This case highlights individual patient factors to consider in the battle against COVID-19 in immunosuppressed patients. Non-viral infections must also be considered despite the ongoing pandemic. Determining protective antibody titers can guide booster vaccine recommendations. REFERENCE #1: Sonani B, Aslam F, Goyal A, Patel J, Bansal P. COVID-19 vaccination in immunocompromised patients. Clin Rheumatol. 2021;40(2):797-798. doi:10.1007/s10067-020-05547-w REFERENCE #2: Day AL, Winthrop KL, Curtis JR. The effect of disease-modifying antirheumatic drugs on vaccine immunogenicity in adults. Cleve Clin J Med. 2020;87(11):695-703. Published 2020 Nov 2. doi:10.3949/ccjm.87a.20056 REFERENCE #3: COVID-19 Vaccine Clinical Guidance Summaryfor Patients with Rheumatic and Musculoskeletal Diseases DISCLOSURES: No relevant relationships by Vernon Chan, source=Web Response No relevant relationships by Dana Daoud, source=Web Response No relevant relationships by Jeet Lund, source=Web Response

Immunological response after mild COVID-19: How long will it last?

Immunological response after mild COVID-19: How long will it last?

Development of a new peptide-bead coupling method for an all peptide–based Luminex multiplexing assay for detection of Plasmodium falciparum antibody responses

Using a recombinant protein antigen for antibody testing shows a sum of antibody responses to multiple different immune epitopes existing in the protein antigen. In contrast, the antibody testing to an immunogenic peptide epitope reflects a singular antibody response to the individual peptide epitope. Therefore, using a panel of peptide epitopes provides an advantage for profiling multiple singular antibody responses with potential to estimate recent malaria exposure in human infections. However, transitioning from malaria immune epitope peptide-based ELISA to an all peptide bead-based multiplex Luminex assay presents some challenges including variation in the ability of different peptides to bind beads. The aim of this study was to develop a peptide coupling method while demonstrating the utility of these peptide epitopes from multiple stage antigens of Plasmodium falciparum for measuring antibodies.Successful coupling of peptide epitopes to beads followed three steps: 1) development of a peptide tag appended to the C-terminus of each peptide epitope consisting of beta-alanine–lysine (x 4)--cysteine, 2) bead modification with a high concentration of adipic acid dihydrazide, and 3) use of the peptide epitope as a blocker in place of the traditional choice, bovine serum albumin (BSA). This new method was used to couple 12 peptide epitopes from multiple stage specific antigens of P. falciparum, 1 Anopheles mosquito salivary gland peptide, and 1 Epstein-Barr virus peptide as an assay control. The new method was applied to testing of IgG in pooled samples from 30 individuals with previously repeated malaria exposure in western Kenya and IgM and IgG in samples from 37 U.S. travelers with recent exposure to malaria.The new peptide-bead coupling method and subsequent multiplex Luminex assay showed reliable detection of IgG to all 14 peptides in Kenyan samples. Among 37 samples from U.S. travelers recently diagnosed with malaria, IgM and IgG to the peptide epitopes were detected with high sensitivity and variation. Overall, the U.S. travelers had a much lower positivity rates of IgM than IgG to different peptide epitopes, ranging from a high of 62.2% positive for one epitope to a low of only 5.4% positive for another epitope. In contrast, the travelers had IgG positive rates from 97.3% to 91.9% to various peptide epitopes. Based on the different distribution in IgM and IgG positivity to overall number of peptide epitopes and to the number of pre-erythrocytic, erythrocytic, gametocytic, and salivary stage epitopes at the individual level, four distinct patterns of IgM and IgG responses among the 37 samples from US travelers were observed. Independent peptide-bead coupling and antibody level readout between two different instruments also showed comparable results.Overall, this new coupling method resolves the peptide-bead coupling challenge, is reproducible, and can be applied to any other immunogenic peptide epitopes. The resulting all peptide bead-based multiplex Luminex assay can be expanded to include other peptide epitopes of P. falciparum, different malaria species, or other diseases for surveillance, either in US travelers or endemic areas.

Ultrafast, sensitive, and portable detection of COVID-19 IgG using flexible organic electrochemical transistors.

The outbreak of COVID-19 and its continued spread have seriously threatened public health. Antibody testing is essential for infection diagnosis, seroepidemiological analysis, and vaccine evaluation. However, convenient, fast, and accurate antibody detection remains a challenge in this protracted battle. Here, we report an ultrafast, low-cost, label-free, and portable SARS-CoV-2 immunoglobulin G (IgG) detection platform based on organic electrochemical transistors (OECTs), which can be remotely controlled by a mobile phone. To enable faster detection, voltage pulses are applied on the gate electrode of the OECT to accelerate binding between the antibody and antigen. By optimizing ion concentrations and pH values of test solutions, we realize specific detection of SARS-CoV-2 IgG in several minutes with a detectable region from 10 fM to 100 nM, which encompasses the range of serum SARS-CoV-2 IgG levels in humans. These portable sensors show promise for use in diagnosis and prognosis of COVID-19.

Epidemiological risk factors associated with primary infection by Epstein–Barr virus in HIV-1-positive subjects in the Brazilian Amazon region

To identify the prevalence and risk factors for primary Epstein–Barr virus (EBV) infection in human immunodeficiency virus (HIV)-1-positive adult treatment-naïve patients between January 2018 and December 2019 in a state of the Brazilian Amazon region. A total of 268 HIV-1 positive patients and 65 blood donors participated in the study. Epidemiological data were obtained from medical records and through a designed questionnaire. EBV infection was screened by the semiquantitative detection of anti-viral capsid antigen (VCA) EBV IgM and IgG, followed by molecular detection of the EBNA-3C gene. The plasma viral loads of HIV-1 and EBV were quantified using a commercial kit. The prevalence of primary coinfection was 7.12%. The associated risk factors were education level, family income, history of illicit drug use and sexually transmitted infections, homosexual contact and condom nonuse. Approximately 58.5% had late initiation of highly active antiretroviral therapy, which influenced the risk of HIV-EBV 1/2 multiple infection (odds ratio (OR): 4.76; 95% CI 1.51–15.04) and symptom development (p = 0.004). HIV viral load was associated with patient age (OR: 2.04; 95% CI 2.01–2.07; p = 0.026) and duration of illicit drug use (OR: 1.57; 95% CI 1.12–2.22; p = 0.0548). EBV viral load was associated with younger age (OR: 0.82; 95% CI 0.79–1.03; p = 0.0579). The replication of both viruses was associated with symptom development (HIV = OR: 2.06; 95% CI 1.22–3.50; p = 0.0073; EBV = OR: 8.81; 95% CI 1–10; p = 0.0447). The prevalence of HIV/EBV coinfection was lower than that observed in other studies, and social vulnerability and promiscuous sexual behavior were associated risk factors. A long time of HIV-1 infection, without therapy, influenced the risk of coinfection and disease progression. The viral loads of both viruses may be associated with some epidemiological aspects of the population.

Особенности лабораторной диагностики ЦМВИ методом ИФА (IgМ, IgG) за период 2014-2020 гг. в Кыргызстане

This article discusses the problem of informing students of medical universities in Kyrgyzstan about CMVI, as well as an analysis of the population survey by ELISA for the detection of specific immunoglobulins of class M and G for 7 years (2014–2020). The article provides an analysis of the surveyed by sex of all ages, which allows us to conclude that the bulk of the surveyed are women of childbearing age. Thus, cytomegalovirus infection poses a particular danger to the fetus, up to its intrauterine death. The work is interdisciplinary in nature, written at the intersection of medical microbiology, epidemiology and public health and health care. Considerable attention in the work is paid to the fact that those examined by the ELISA method for specific IgM are ten times less than for the detection of specific IgG. Although it is the detection of specific IgM that poses a particular danger to the fetus — it can lead to its especially life-threatening complications such as: heart disease, retinopathy, which can lead to blindness, deafness and even mental retardation, intrauterine hypotrophy, immaturity, prematurity, chronic intrauterine fetal hypoxia. The idea is substantiated how important it is for future and practicing doctors to inform the population about this infection, which will help in the future to timely detect IgM and possibly save the fetus from intrauterine death. Using the results of an ELISA test for the detection of specific IgM and IgG, which today is one of the most reliable and affordable ways to detect a disease, the author proves in his studies the huge problem of informing and examining the population. The topic under consideration will be of particular interest to specialists in the field of public health and health care, since this is a truly national problem. The presented work indicates that CMVI is currently a serious medical and social problem. This problem is extremely poorly understood and requires further study.

Electrochemiluminescence Immunoassay Platform with Immunoglobulin G-Encapsulated Gold Nanoclusters as a "Two-In-One" Probe.

Biomolecule-functionalized Au nanoclusters (AuNCs) have drawn great interest in the electrochemiluminescence (ECL) field due to their unique optical/electrical properties, biocompatibility, and versatile bioapplication potentials. Herein, we proposed a two-in-one ECL probe of immunoglobulin G-encapsulated AuNCs (IgG-AuNCs) for the development of a high-performance ECL immunoassay (ECLIA) platform. The IgG-AuNCs were not only used as an ECL probe due to their excellent anodic ECL performance with triethylamine (TEA) as a coreactant but also used as the biorecognition element because of their well-retained bioactivity of the IgG. As a proof of concept, a new type of competitive immunosensing platform has been applied to detect IgG representing several merits of facile preparation, rapid detection, sample saving, and good analytical performance. The sensing platform exhibited a linear range of 0.5-50,000 ng/mL with a limit of detection of 0.06 ng/mL for IgG detection with high selectivity. In addition, this convenient ECLIA platform also performed well in real serum sample detection. Notably, our work not only proved the "two-in-one" immuno-AuNC probe-based ECLIA strategy but also developed a rational framework for study of ECL bioassay platforms based on multifunctional AuNCs and other related nanomaterials.

Competitive ELISA for a serologic test to detect dengue serotype-specific anti-NS1 IgGs using high-affinity UB-DNA aptamers

Serologic tests to detect specific IgGs to antigens related to viral infections are urgently needed for diagnostics and therapeutics. We present a diagnostic method for serotype-specific IgG identification of dengue infection by a competitive enzyme-linked immunosorbent assay (ELISA), using high-affinity unnatural-base-containing DNA (UB-DNA) aptamers that recognize the four categorized serotypes. Using UB-DNA aptamers specific to each serotype of dengue NS1 proteins (DEN-NS1), we developed our aptamer–antibody sandwich ELISA for dengue diagnostics. Furthermore, IgGs highly specific to DEN-NS1 inhibited the serotype-specific NS1 detection, inspiring us to develop the competitive ELISA format for dengue serotype-specific IgG detection. Blood samples from Singaporean patients with primary or secondary dengue infections confirmed the highly specific IgG detection of this format, and the IgG production initially reflected the serotype of the past infection, rather than the recent infection. Using this dengue competitive ELISA format, cross-reactivity tests of 21 plasma samples from Singaporean Zika virus-infected patients revealed two distinct patterns: 8 lacked cross-reactivity, and 13 were positive with unique dengue serotype specificities, indicating previous dengue infection. This antigen-detection ELISA and antibody-detection competitive ELISA combination using the UB-DNA aptamers identifies both past and current viral infections and will facilitate specific medical care and vaccine development for infectious diseases.

Dynamic IgG seropositivity after rollout of CoronaVac and BNT162b2 COVID-19 vaccines in Chile: a sentinel surveillance study

BackgroundBy July 14, 2021, 81·3 % of adults (aged ≥18 years) in Chile had received a first SARS-CoV-2 vaccine and 72·3% had received a second SARS-CoV-2 vaccine, with the majority of people given Sinovac's inactivated CoronaVac vaccine (75·3% of vaccines dispensed) or Pfizer–BioNTech's mRNA BNT162b2 vaccine (20·9% of vaccines dispensed). Due to the absence of simultaneous real-world data for these vaccines, we aimed to compare SARS-CoV-2 IgG positivity between vaccines using a dynamic national monitoring strategy.MethodsFrom March 12, 2021, 28 testing stations for SARS-CoV-2 IgG detection were installed in hotspots based on cellular-phone mobility tracking within the most populated cities in Chile. Individuals voluntarily approaching the testing stations were invited to do a lateral flow test by finger prick and respond to a questionnaire on sociodemographic characteristics, vaccination status (including type of vaccine if one was received), variables associated with SARS-CoV-2 exposure, and comorbidities. We compared the proportion of individuals testing positive for anti-SARS-CoV-2 IgG across sites by week since vaccination between recipients of CoronaVac and BNT162b2. Unvaccinated participants served as a control population and were matched to vaccinated individuals on the basis of date of presentation to the testing station, gender, and age group. Individuals were excluded from the analysis if they were younger than 18 years, had no declared gender, had an invalid IgG test result, had previously tested positive for SARS-CoV-2 infection on PCR, could not recall their vaccination status, or had been immunised against COVID-19 with vaccines other than CoronaVac or BNT162b2. Here, we report data collected up to July 2, 2021.FindingsOf 64 813 individuals enrolled, 56 261 were included in the final analysis, of whom 33 533 (59·6%) had received at least one dose of the CoronaVac vaccine, 8947 (15·9%) had received at least one dose of the BNT162b2 vaccine, and 13 781 (24·5%) had not received a vaccine. SARS-CoV-2 IgG positivity during week 4 after the first dose of CoronaVac was 28·1% (95% CI 25·0–31·2; 220 of 783 individuals), reaching a peak of 77·4% (75·5–79·3; 1473 of 1902 individuals) during week 3 after the second dose. SARS-CoV-2 IgG positivity during week 4 after the first dose of the BNT162b2 vaccine was 79·4% (75·7–83·1; 367 of 462 individuals), increasing to 96·5% (94·9–98·1; 497 of 515 individuals) during week 3 after the second dose and remaining above 92% until the end of the study. For unvaccinated individuals, IgG seropositivity ranged from 6·0% (4·4–7·6; 49 of 810 individuals) to 18·7% (12·5–24·9; 28 of 150 individuals) during the 5 month period. Regression analyses showed that IgG seropositivity was significantly lower in men than women and in people with diabetes or chronic diseases for CoronaVac vaccine recipients (p<0·0001), and for individuals aged 60 years and older compared with people aged 18–39 years for both vaccines (p<0·0001), 3–16 weeks after the second dose.InterpretationIgG seropositivity was lower after CoronaVac than after BNT162b2 and declined over time since vaccination for CoronaVac recipients but not BNT162b2 recipients. Prolonged IgG monitoring will allow further evaluation of seropositivity overtime, providing data, in conjunction with effectiveness studies, for possible future re-assessment of vaccination strategies.FundingInstituto Sistemas Complejos de Ingeniería and Ministerio de Salud Chile.TranslationFor the Spanish translation of the abstract see Supplementary Materials section.

Classification of measles breakthrough cases in an elimination setting using a comprehensive algorithm of laboratory results: why sensitive and specific IgM assays are important

ObjectiveIn 2006, a measles outbreak occurred in Catalonia (Spain), six years after endemic measles was declared eliminated. This study aimed to classify 19 confirmed measles breakthrough cases (BC) using a high-performance avidity assay developed in 2010. MethodsSerum specimens were tested by indirect IgG, indirect IgM, capture IgM enzyme immunoassay, an endpoint-titer IgG avidity assay, and a plaque reduction neutralization assay. Serology and RNA detection results were combined in an algorithm for measles confirmation and classification of breakthrough cases and analyzed with clinical and epidemiological data. ResultsOf 19 samples, thirteen (68%) were conclusive with the classification of BCs, and six (32%) had false-positive IgM results on an indirect-format assay; they were classified as rash and fever illness of undetermined etiology. BCs were primary vaccine failures (seven or 54%), secondary vaccine failures (four or 31%), and two (15%) could not be classified. ConclusionsIn measles elimination settings, high-performing assays and a comprehensive algorithm of laboratory results (IgG, IgM, and RNA detection), including IgG avidity and PRN results when necessary, can assist in accurate laboratory confirmation and classification of suspected measles cases for surveillance. Highly specific IgM assays are required to minimize the number of false-positive results.

IgG Antibodies Generation and Side Effects Caused by Ad5-nCoV Vaccine (CanSino Biologics) and BNT162b2 Vaccine (Pfizer/BioNTech) among Mexican Population.

SARS-CoV-2 has rapidly generated a pandemic. Vaccines are currently being rolled out to control the viral spread and prevent deaths. Emergency vaccines, using new platforms, have been approved. Their effectiveness, safety and immunogenicity in different populations are not fully known. This study aimed to discover the immunogenicity of the messenger ribonucleic acid (mRNA) BNT162b2 and adenovirus vector Ad5-nCoV vaccines through IgG antibody generation against subunit 1 of protein S (S1 IgG) and assess the side effects of the vaccines. A total of 115 vaccinated people were included, 61 of whom received the BNT162b2 vaccine, while 54 received Ad5-nCoV. Measurements of S1 IgG antibodies were carried out using the enzyme-linked immunosorbent assay (ELISA) technique. The BNT162b2 vaccine generated S1 IgG antibodies in 80.3% of the participants after the first dose. The number of seropositive participants increased to 98.36% with the administration of the second dose. The Ad5-nCoV vaccine generated S1 IgG antibodies in 88.89% of those vaccinated. Women generated more antibodies when administered either vaccine. There were no serious adverse effects from vaccination. In conclusion, not all participants had detectable S1 IgG antibodies. The Ad5-nCoV vaccine presented the most seronegative cases. The studied vaccines were shown to be safe.

Assessment of avidity related to IgG subclasses in SARS-CoV-2 Brazilian infected patients

SARS-CoV-2 is considered a global emergency, resulting in an exacerbated crisis in the health public in the world. Although there are advances in vaccine development, it is still limited for many countries. On the other hand, an immunological response that mediates protective immunity or indicates that predict disease outcome in SARS-CoV-2 infection remains undefined. This work aimed to assess the antibody levels, avidity, and subclasses of IgG to RBD protein, in symptomatic patients with severe and mild forms of COVID-19 in Brazil using an adapted in-house RBD-IgG ELISA. The RBD IgG-ELISA showed 100% of specificity and 94.3% of sensibility on detecting antibodies in the sera of hospitalized patients. Patients who presented severe COVID-19 had higher anti-RBD IgG levels compared to patients with mild disease. Additionally, most patients analyzed displayed low antibody avidity, with 64.4% of the samples of patients who recovered from the disease and 84.6% of those who died in this avidity range. Our data also reveals an increase of IgG1 and IgG3 levels since the 8th day after symptoms onset, while IgG4 levels maintained less detectable during the study period. Surprisingly, patients who died during 8–14 and 15–21 days also showed higher anti-RBD IgG4 levels in comparison with the recovered (P < 0.05), suggesting that some life-threatening patients can elicit IgG4 to RBD antibody response in the first weeks of symptoms onset. Our findings constitute the effort to clarify IgG antibodies' kinetics, avidity, and subclasses against SARS-CoV-2 RBD in symptomatic patients with COVID-19 in Brazil, highlighting the importance of IgG antibody avidity in association with IgG4 detection as tool laboratory in the follow-up of hospitalized patients with more significant potential for life-threatening.

SERS-based lateral flow immunoassay for sensitive and simultaneous detection of anti-SARS-CoV-2 IgM and IgG antibodies by using gap-enhanced Raman nanotags

The lateral flow immunoassay (LFIA) has played a crucial role in early diagnosis during the current COVID-19 pandemic owing to its simplicity, speed and affordability for coronavirus antibody detection. However, the sensitivity of the commercially available LFIAs needs to be improved to better prevent the spread of the infection. Here, we developed an ultra-sensitive surface-enhanced Raman scattering-based lateral flow immunoassay (SERS-based LFIA) strip for simultaneous detection of anti-SARS-CoV-2 IgM and IgG by using gap-enhanced Raman nanotags (GERTs). The GERTs with a 1 nm gap between the core and shell were used to produce the “hot spots”, which provided about 30-fold enhancement as compared to conventional nanotags. The COVID-19 recombinant antigens were conjugated on GERTs surfaces and replaced the traditional colloidal gold for the Raman sensitive detection of human IgM and IgG. The LODs of IgM and IgG were found to be 1 ng/mL and 0.1 ng/mL (about 100 times decrease was observed as compared to commercially available LFIA strips), respectively. Moreover, under the condition of common nano-surface antigen, precise SERS signals proved the unreliability of quantitation because of the interference effect of IgM on IgG.

Monitoring Specific IgM and IgG Production Among Severe COVID-19 Patients Using Qualitative and Quantitative Immunodiagnostic Assays: A Retrospective Cohort Study.

The purpose of this study is to monitor specific anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) IgG and IgM antibody production in patients with severe forms of coronavirus disease 2019 (COVID-19) using various commercially available quantitative and qualitative tests. The sera of 23 confirmed COVID-19 patients were processed for anti-SARS-CoV-2 IgG and IgM detection. Three different immunoassays, viz. Abbott Architect® SARS-CoV-2 IgG assay, and two quantitative tests, ANSH® SARS-CoV-2 and AESKULISA® SARS-CoV-2 Nucleocapsid Protein (NP), were performed and the results pooled, from diagnosis to serum collection. Seroconversion rates were computed for all 3 assays, and possible correlations were tested using the Pearson correlation coefficient and Cohen’s kappa coefficient. Overall, 70 combinations of qualitative and quantitative IgG and IgM results were pooled and analyzed. In the early phase (0-4 days after diagnosis), in all tests, IgG seroconversion rates were 43%-61%, and increased in all tests gradually to 100% after 15 days. The Pearson correlation coefficient showed a strong positive relationship between the qualitative IgG test results and both quantitative IgG tests. IgM detection was inconsistent, with maximal concentrations and seroconversion rates between 10-15 days after diagnosis and slight-to-fair agreement between the two quantitative immunoassays. There was no significant association between mortality with IgG or IgM seroconversion or concentrations. Patients with severe COVID-19 develop an early, robust anti-SARS-CoV-2 specific humoral immune response involving IgG immunoglobulins. Further comparative studies are warranted to analyze the value of serological testing in predicting the severity of COVID-19 and detecting prior exposure.

Linear Cryogel Arrays: On the Fast Track for Borreliosis Detection.

The detection of IgG/IgM antibodies is a crucial tool for the diagnosis of infectious diseases as they give specific information such as the stage of infection or when it approximately occurred. In this work, a linear cryogel array (LCA) technology is described for the detection of IgG and IgM antibodies, indicative of a borreliosis infection in human sera. The LCA consists of a transparent capillary filled with functionalized cryogel compartments. For the generation of these cryogel arrays, solutions containing a photo-copolymer and the appropriate antigens are sucked into a surface-modified glass capillary. The solution compartments are separated from each other through air pockets. After freezing the solutions, a photo-induced cross-linking process is performed, through which the solutions are transformed into cryogel compartments, covalently attached to the capillary walls. We show that the LCA technology allows the simultaneous detection of IgG and IgM antibodies via a sandwich immunoassay in sera from Borrelia-infected patients within 1 h for sample sizes of only 12 μL. A study with sera from 42 patients conducted with the LCAs and referenced - depending on the source of the sera - to a commercial line immunoassay and a chemiluminescent immunoassay, which are currently widely used for Lyme disease screening, demonstrates the diagnostic potential of the approach.

1590P Treatment outcomes and antibody immunity to SARS-CoV-2 in patients with hematological malignancies

Since SARS-CoV-2 infection heavily affects vulnerable populations including those with immune suppression, it is of special value to study clinical course, treatment outcomes, and immunity in patients (pts) with hematological (hem) malignancies. CHRONOS19 is an ongoing observational study in adult pts (≥18 years) with hem diseases (malignant or non-malignant) and COVID-19 in Russia. This web-based registry collected de-identified data from 15 centers all over the country at 30, 90, and 180 days after lab-confirmed or suspected (based on CT and/or clinical symptoms) COVID-19 diagnosis. The primary endpoint was 30-day all-cause mortality. As of data cut-off on April 14, 2021, 626 pts were enrolled in the study; 562 were eligible for primary endpoint assessment, n (%): M/F 271 (48%) / 291 (52%), median age 56 [18-90] years, malignant disease in 516 (92%) pts, among them induction phase / relapse or refractory / remission / NA in 180 (35%) / 120 (23%) / 187 (36%) / 29 (6%) pts. Thirty-day all-cause mortality in pts with hem malignancies was 19%; 83% of deaths were due to COVID-19 complications. No increase of hem disease relapse rate after COVID-19 was observed at Day 90 or Day 180, although 180-day data was still not mature at the time of analysis. IgG to SARS-CoV-2 was detected in 84% of pts with hem malignancies (167/199). The highest rate of detected antibody immunity was found in pts with chronic myeloproliferative neoplasms (100%; 13/13), HL (100%; 12/12), and multiple myeloma (97%; 34/35), the lowest – in pts with CLL (62%; 8/13) and NHL (60%; 6/10 and 56%; 10/18 for low-grade and high-grade lymphoma, respectively). igG detection rate in CD20+ lymphoma (60%) was significantly lower than in HL or T-cell lymphoma (p=0.004). Pts with ECOG 0-2 throughout the disease had a high rate of antibody immunity (90%; 104/116) vs. those with ECOG 3-4 at the time of COVID-19 diagnosis (77.5%; 31/40) or with worsening of ECOG to 3-4 during the disease (78%; 36/46). Five cases of SARS-CoV-2 re-infection were described. Pts with hem malignancies and COVID-19 have higher mortality than the general population. Low post-disease antibody immunity to SARS-CoV-2 and cases of re-infection may justify vaccination of these pts and warrant further research.

Determination of anti‐ADAMTS‐13 autoantibody titers in ELISA: Influence of ADAMTS‐13 presentation and autoantibody detection

BackgroundImmune‐mediated thrombotic thrombocytopenic purpura (iTTP) is caused by inhibitory and/or clearing anti‐ADAMTS‐13 (A Disintegrin and Metalloprotease with ThromboSpondin type 1 repeats, member 13) autoantibodies. To determine the presence and total level of anti‐ADAMTS‐13 autoantibodies, commercial and in‐house developed ELISAs are performed. However, different ELISA methods vary in relation to the presentation of recombinant (r)ADAMTS‐13 and the detection method of the anti‐ADAMTS‐13 autoantibodies. Currently, the influence of those different approaches on anti‐ADAMTS‐13 autoantibody titers is not known. ObjectivesTo assess the influence of different ADAMTS‐13 presentation‐ and autoantibody detection methods on anti‐ADAMTS‐13 autoantibody titers in ELISA. Materials/MethodsAnti‐ADAMTS‐13 autoantibody titers from 18 iTTP patients were determined using four different set‐ups of anti‐ADAMTS‐13 autoantibody ELISAs. The ELISAs varied in the used presentation of rADAMTS‐13 (directly coated full‐length rADAMTS‐13, directly coated rMDTCS and rT2C2, or antibody‐captured full‐length rADAMTS‐13) and the detection antibodies (polyclonal anti‐human IgG or monoclonal anti‐human IgG1‐4 antibodies). ResultsStrong correlations between the different anti‐ADAMTS‐13 autoantibody ELISA approaches were observed, when using polyclonal anti‐human IgG detection antibodies recognizing all IgG subclasses similarly, independent of the method of rADAMTS‐13 presentation. Anti‐ADAMTS‐13 autoantibody titers correlated less when using a mixture of monoclonal anti‐human IgG1–4, because not all IgG subclasses were recognized with similar affinities. ConclusionAnti‐ADAMTS‐13 autoantibody levels using different methods of rADAMTS‐13 presentation strongly correlate. However, the levels of anti‐ADAMTS‐13 autoantibodies are highly dependent on the detection antibody used, which should detect all IgG subclasses (IgG1–4) equally well.

Breastfeeding in Mothers with COVID-19: Insights from Laboratory Tests and Follow-Up from Early Outbreak of the Pandemic in China.

Objective: The outbreak of Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) threatens a surging number of community groups within society, including women actively breastfeeding. Breastfeeding involves intimate behaviors, a major transmission route of SARS-CoV-2, and is integral to the close mother-baby relationship highly correlated with maternal psychological status. Materials and Methods: Twenty-three pregnant women and puerperae with either confirmed or suspected diagnoses of COVID-19 were enrolled in the study. The clinical characteristics and outcomes of the mothers and neonates were recorded. The presence of SARS-CoV-2, IgG, and IgM in breast milk, maternal blood, and infant blood, together with feeding patterns, was assessed within 1 month after delivery. Feeding patterns and maternal psychological status were also recorded in the second follow-up. Results: No positive detection of SARS-CoV-2 was found in neonates. All breast milk samples were negative for the detection of SARS-CoV-2. The presence of IgM for SARS-CoV-2 in breast milk was correlated with IgM presence in the maternal blood. The results of IgG detection for SARS-CoV-2 were negative in all breast milk samples. All infants were in a healthy condition in two follow-ups, and antibody tests for SARS-CoV-2 were negative. The rate of breast milk feeding increased during two follow-ups. All mothers receiving a second follow-up experienced negative psychological factors and status. Conclusions: Our findings support the feasibility of breastfeeding in women infected with SARS-CoV-2. The additional negative psychological status of mothers due to COVID-19 should also be considered during the puerperium period.