Testing IgG antibodies against the RBD of SARS-CoV-2 is sufficient and necessary for COVID-19 diagnosis

The COVID-19 pandemic and the fast global spread of the disease resulted in unprecedented decline in world trade and travel. A critical priority is, therefore, to quickly develop serological diagnostic capacity and identify individuals with past exposure to SARS-CoV-2. In this study serum samples obtained from 309 persons infected by SARS-CoV-2 and 324 of healthy, uninfected individuals as well as serum from 7 COVID-19 patients with 4–7 samples each ranging between 1–92 days post first positive PCR were tested by an “in house” ELISA which detects IgM, IgA and IgG antibodies against the receptor binding domain (RBD) of SARS-CoV-2. Sensitivity of 47%, 80% and 88% and specificity of 100%, 98% and 98% in detection of IgM, IgA and IgG antibodies, respectively, were observed. IgG antibody levels against the RBD were demonstrated to be up regulated between 1–7 days after COVID-19 detection, earlier than both IgM and IgA antibodies. Study of the antibody kinetics of seven COVID 19 patients revealed that while IgG levels are high and maintained for at least 3 months, IgM and IgA levels decline after a 35–50 days following infection. Altogether, these results highlight the usefulness of the RBD based ELISA, which is both easy and cheap to prepare, to identify COVID-19 patients even at the acute phase. Most importantly our results demonstrate that measuring IgG levels alone is both sufficient and necessary to diagnose past exposure to SARS-CoV-2.

Download Full-text

Immunoglobulin G and A Antibody Responses to Bacteroides forsythus and Prevotella intermedia in Sera and Synovial Fluids of Arthritis Patients

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.10.6.1043-1050.2003 ◽

2003 ◽

Vol 10 (6) ◽

pp. 1043-1050 ◽

Cited By ~ 49

Author(s):

Ketil Moen ◽

Johan G. Brun ◽

Tor Magne Madland ◽

Turid Tynning ◽

Roland Jonsson

Keyword(s):

Immune Responses ◽

Immunoglobulin G ◽

Enzyme Linked Immunosorbent Assay ◽

Prevotella Intermedia ◽

Igg Antibodies ◽

Serum Samples ◽

Igg Antibody ◽

Iga Antibodies ◽

Iga Antibody ◽

Antibody Levels

ABSTRACT The objective of the present study was to investigate immunoglobulin G (IgG) and IgA antibody immune responses to Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, and Candida albicans in the sera of patients with rheumatoid arthritis (RA), the synovial fluid (SF) of patients with RA (RA-SF samples), and the SF of patients without RA (non-RA-SF samples). An enzyme-linked immunosorbent assay was used to determine IgG and IgA antibody levels in 116 serum samples from patients with RA, 52 RA-SF samples, and 43 non-RA-SF samples; and these were compared with those in SF samples from 9 patients with osteoarthritis (OA-SF samples) and the blood from 100 donors (the control [CTR] group). Higher levels of IgG antibodies against B. forsythus (P < 0.0001) and P. intermedia (P < 0.0001) were found in non-RA-SF samples than in OA-SF samples, and higher levels of IgG antibodies against B. forsythus (P = 0.003) and P. intermedia (P = 0.024) were found in RA-SF samples than in OA-SF samples. Significantly higher levels of IgA antibodies against B. forsythus were demonstrated in both RA-SF and non-RA-SF samples than in OA-SF samples. When corrected for total Ig levels, levels of IgG antibody against B. forsythus were elevated in RA-SF and non-RA-SF samples compared to those in OA-SF samples. Lower levels of Ig antibodies against B. forsythus were found in the sera of patients with RA than in the plasma of the CTR group for both IgG (P = 0.003) and IgA (P < 0.0001). When corrected for total Ig levels, the levels of IgG and IgA antibodies against B. forsythus were still found to be lower in the sera from patients with RA than in the plasma of the CTR group (P < 0.0001). The levels of antibodies against P. gingivalis and C. albicans in the sera and SF of RA and non-RA patients were comparable to those found in the respective controls. The levels of IgG and IgA antibodies against B. forsythus were elevated in SF from patients with RA and non-RA-SF samples compared to those in OA-SF samples. Significantly lower levels of IgG and IgA antibodies against B. forsythus were found in the sera of patients with RA than in the plasma of the CTR group. This indicates the presence of an active antibody response in synovial tissue and illustrates a potential connection between periodontal and joint diseases.

Download Full-text

Viral load and antibody levels in patients with COVID-19

GSC Advanced Research and Reviews ◽

10.30574/gscarr.2021.8.3.0180 ◽

2021 ◽

Vol 8 (3) ◽

pp. 010-018

Author(s):

Iva Christova ◽

Iva Trifonova ◽

Teodora Gladnishka ◽

Elena Dragusheva ◽

Georgi Popov ◽

...

Keyword(s):

Viral Load ◽

High Viral Load ◽

Igg Antibodies ◽

Rt Pcr ◽

Serum Samples ◽

Weekly Basis ◽

Specific Antibody Response ◽

Viral Loads ◽

Antibody Levels ◽

Kinetics Of

Relations between viral load, antibody levels and COVID-19 severity are not well studied and results from such investigations are controversial. In this study, we investigated kinetics of viral load and antibody responses to SARS-CoV-2 in 20 patients with COVID-19 and analysed the association with disease severity. The patients were followed on weekly basis within the first month after the onset and then once per month for the next 4 months. Serum samples were tested for IgA, IgM, and IgG antibodies against SARS-CoV-2 using ELISA tests. SARS-CoV-2 viral load in nasopharyngeal swabs was measured by quantitative Realtime RT-PCR. For vast majority of the patients, the viral loads were at their highest levels at presentation and then declined gradually. Despite development of specific antibody response 7-11 days after the onset of COVID-19, SARS-CoV-2 RNA was still detected in nasopharyngeal swabs of most of the patients. There was no direct link between viral load and severity of COVID-19: some of mild and some of severe cases started with a high viral load. There was a relationship between the time from the onset of the disease and the viral load: the highest viral load was in the first days. In more severe cases, there was a tendency for slower reduction in viral load and longer detection of SARS-CoV-2 virus. Levels of the specific antibodies increased earlier and to higher levels and were present for longer time in patients with more severe manifestations of COVID-19 than in those with milder disease.

Download Full-text

Large-Scale Study of Antibody Titer Decay following BNT162b2 mRNA Vaccine or SARS-CoV-2 Infection

Vaccines ◽

10.3390/vaccines10010064 ◽

2021 ◽

Vol 10 (1) ◽

pp. 64

Author(s):

Ariel Israel ◽

Yotam Shenhar ◽

Ilan Green ◽

Eugene Merzon ◽

Avivit Golan-Cohen ◽

...

Keyword(s):

Large Scale ◽

Immune Protection ◽

Igg Antibodies ◽

Igg Antibody ◽

Exponential Decrease ◽

Previous Infection ◽

History Of ◽

Antibody Titers ◽

Antibody Levels ◽

Kinetics Of

Immune protection following either vaccination or infection with SARS-CoV-2 is thought to decrease over time. We designed a retrospective study, conducted at Leumit Health Services in Israel, to determine the kinetics of SARS-CoV-2 IgG antibodies following administration of two doses of BNT162b2 vaccine, or SARS-CoV-2 infection in unvaccinated individuals. Antibody titers were measured between 31 January 2021, and 31 July 2021 in two mutually exclusive groups: (i) vaccinated individuals who received two doses of BNT162b2 vaccine and had no history of previous infection with COVID-19 and (ii) SARS-CoV-2 convalescents who had not received the vaccine. A total of 2653 individuals fully vaccinated by two doses of vaccine during the study period and 4361 convalescent patients were included. Higher SARS-CoV-2 IgG antibody titers were observed in vaccinated individuals (median 1581 AU/mL IQR [533.8–5644.6]) after the second vaccination than in convalescent individuals (median 355.3 AU/mL IQR [141.2–998.7]; p < 0.001). In vaccinated subjects, antibody titers decreased by up to 38% each subsequent month while in convalescents they decreased by less than 5% per month. Six months after BNT162b2 vaccination 16.1% subjects had antibody levels below the seropositivity threshold of <50 AU/mL, while only 10.8% of convalescent patients were below <50 AU/mL threshold after 9 months from SARS-CoV-2 infection. This study demonstrates individuals who received the Pfizer-BioNTech mRNA vaccine have different kinetics of antibody levels compared to patients who had been infected with the SARS-CoV-2 virus, with higher initial levels but a much faster exponential decrease in the first group.

Download Full-text

Establishment of the diagnostic cut-off points for levels of serum antibodies to pertussis toxin in adults in Poland

Medycyna Doświadczalna i Mikrobiologia ◽

10.32394/mdm.70.2.3 ◽

2018 ◽

pp. 139-147

Author(s):

Waldemar Rastawicki ◽

Natalia Rokosz-Chudzial ◽

Karolina Śmietańska ◽

Anna Chróst ◽

Urszula Roguska

Keyword(s):

Pertussis Toxin ◽

Blood Donors ◽

Adult Population ◽

Arithmetic Mean ◽

Igg Antibodies ◽

Serum Samples ◽

International Standard ◽

Iga Antibodies ◽

Antibody Levels ◽

Serology Testing

Introduction: Standardization of ELISA tests for the diagnosis of infections caused by B. pertussis remains challenging despite efforts to improve it. It is recommended that serology testing should use purified pertussis toxin as the only coating antigen and that concentration of antibodies should be expressed in international units per mL (IU/ml) according to the First WHO International Standard for Pertussis Antiserum. However, available commercial ELISAs are often of different antigen composition and quality and sometimes do not calculate antibody levels in IU/ml. Furthermore, for single-sample serology, various cut-off values for IgG- and IgA-anti pertussis toxin in different EU reference laboratories have been proposed. The aim of this study was to establish of the diagnostic cut-off points for levels of serum IgG and IgA antibodies to pertussis toxin in adults in Poland and determine the seroprevalence of these antibodies among Polish blood donors. Materials and Methods: The IgG and IgA antibodies in serum samples collected from 236 blood donors were measured by in-house ELISA with purified pertussis toxin as antigen (0,5 µg/ml). The cut-off value was settled by calculation the OD450 results from all blood donors (arithmetic mean plus 2 standard deviations). Antibody levels were quantitated with respect to the First WHO International Standard for Pertussis Antiserum (06/140) and results were expressed in IU/mL. Results: According to the obtained results, in the case of searching for IgG and IgA antibodies for pertussis toxin, a cut-off of 120 IU/ml and 16 IU/ml respectively, should be taken as diagnostic significant level in the adult population in Poland. A study showed the presence of IgG antibodies at a diagnostic level in 18 (7.6%) samples, and IgA antibodies to pertussis toxin in 14 (5.9%) serum samples obtained from blood donors. Conclusions: The established in our investigation cut-off values for anti-PT IgG and IgA good correspond with values recommended by reference laboratories in other European countries.

Download Full-text

Identification and Pilot Evaluation of Salivary Peptides from Anopheles albimanus as Biomarkers for Bite Exposure and Malaria Infection in Colombia

International Journal of Molecular Sciences ◽

10.3390/ijms21030691 ◽

2020 ◽

Vol 21 (3) ◽

pp. 691 ◽

Cited By ~ 2

Author(s):

Berlin Londono-Renteria ◽

Papa M. Drame ◽

Jehidys Montiel ◽

Ana M. Vasquez ◽

Alberto Tobón-Castaño ◽

...

Keyword(s):

Disease Risk ◽

Mosquito Species ◽

Igg Antibodies ◽

Anopheles Albimanus ◽

Serum Samples ◽

Igg Antibody ◽

Quantitative Immunoassay ◽

Risk Of Disease ◽

Antibody Levels

Insect saliva induces significant antibody responses associated with the intensity of exposure to bites and the risk of disease in humans. Several salivary biomarkers have been characterized to determine exposure intensity to Old World Anopheles mosquito species. However, new tools are needed to quantify the intensity of human exposure to Anopheles bites and understand the risk of malaria in low-transmission areas in the Americas. To address this need, we conducted proteomic and bioinformatic analyses of immunogenic candidate proteins present in the saliva of uninfected Anopheles albimanus from two separate colonies—one originating from Central America (STECLA strain) and one originating from South America (Cartagena strain). A ~65 kDa band was identified by IgG antibodies in serum samples from healthy volunteers living in a malaria endemic area in Colombia, and a total of five peptides were designed from the sequences of two immunogenic candidate proteins that were shared by both strains. ELISA-based testing of human IgG antibody levels against the peptides revealed that the transferrin-derived peptides, TRANS-P1, TRANS-P2 and a salivary peroxidase peptide (PEROX-P3) were able to distinguish between malaria-infected and uninfected groups. Interestingly, IgG antibody levels against PEROX-P3 were significantly lower in people that have never experienced malaria, suggesting that it may be a good marker for mosquito bite exposure in naïve populations such as travelers and deployed military personnel. In addition, the strength of the differences in the IgG levels against the peptides varied according to location, suggesting that the peptides may able to detect differences in intensities of bite exposure according to the mosquito population density. Thus, the An. albimanus salivary peptides TRANS-P1, TRANS-P2, and PEROX-P3 are promising biomarkers that could be exploited in a quantitative immunoassay for determination of human-vector contact and calculation of disease risk.

Download Full-text

Stable IgG-antibody levels in patients with mild SARS-CoV-2 infection

10.1101/2021.06.16.21258960 ◽

2021 ◽

Author(s):

Thomas Akerlund ◽

Katherina Zakikhany ◽

Charlotta Lofstrom ◽

Evelina Lindmark ◽

Henrik Kallberg ◽

...

Keyword(s):

Nucleocapsid Protein ◽

Spike Protein ◽

Igg Antibodies ◽

Serum Samples ◽

Igg Antibody ◽

Time Period ◽

Specific Igg ◽

Antibody Levels ◽

Over Time ◽

Specific Igg Antibodies

More knowledge regarding persistence of antibody response to SARS-CoV-2 infections in the general population with mild symptoms is needed. We measured and compared levels of SARS-CoV-2 spike- and nucleocapsid-specific IgG-antibodies in serum samples from 145 laboratory-confirmed COVID-19 cases and 324 non-cases. The IgG-antibody levels against the spike protein in cases were stable over the time-period studied (14 to 256 days), while antibody levels against the nucleocapsid protein decreased over time.

Download Full-text

Novel multiplex assay for profiling influenza antibodies in breast milk and serum of mother-infant pairs

F1000Research ◽

10.12688/f1000research.16717.1 ◽

2018 ◽

Vol 7 ◽

pp. 1822 ◽

Cited By ~ 2

Author(s):

Kirsi M. Järvinen ◽

Jiong Wang ◽

Antti E. Seppo ◽

Martin Zand

Keyword(s):

Influenza Virus ◽

Breast Milk ◽

Multiplex Assay ◽

Mucosal Protection ◽

Igg Antibodies ◽

Serum Samples ◽

Igg Antibody ◽

Initial Exposure ◽

Antibody Levels ◽

The Impact

Background: During early life, systemic protection to influenza is passively provided by transplacental transfer of IgG antibodies and oral and gastrointestinal mucosal protection via breast milk (BM) containing predominantly IgA. Immune imprinting, influenced by initial exposure of the infant immune system to influenza, has recently been recognized as an important determinant of future influenza immune responses. Methods: We utilized stored frozen BM from a prospective birth cohort to assess immune factors in human milk. The earliest available BM and a paired, timed serum sample was assessed from each of 7 mothers. Paired infant serum samples were assayed at up to three time points during the first 12 months of life, one prior to assumed disappearance of transplacentally transferred IgG, and one after. We utilized a novel multiplex assay to assess mothers’ and infants’ IgG and IgA antibodies in serum to a panel of 30 individual recombinant hemagglutinin (rHA) proteins of influenza virus strains and chimeric rHAs. We also characterized IgA and IgG antibody levels in breast milk providing mucosal protection. Results: Our pilot results, analyzing a small number of samples demonstrate the feasibility of this method for studying paired maternal-infant IgG and IgA anti-influenza immunity patterns. Unlike IgG antibodies, breast milk influenza virus HA-specific IgA antibody levels and patterns were mostly discordant compared to serum. As expected, there was a steady decay of infant influenza specific IgG levels by 6 to 8 months of age, which was not, however, comparable in all infants. In contrast, most of the infants showed an increase in IgA responses throughout the first year of life Conclusions: This new analytical method can be applied in a larger study to understand the impact of maternal imprinting on influenza immunity.

Download Full-text

Novel multiplex assay for profiling influenza antibodies in breast milk and serum of mother-infant pairs

F1000Research ◽

10.12688/f1000research.16717.2 ◽

2019 ◽

Vol 7 ◽

pp. 1822 ◽

Cited By ~ 1

Author(s):

Kirsi M. Järvinen ◽

Jiong Wang ◽

Antti E. Seppo ◽

Martin Zand

Keyword(s):

Influenza Virus ◽

Breast Milk ◽

Multiplex Assay ◽

Mucosal Protection ◽

Igg Antibodies ◽

Serum Samples ◽

Igg Antibody ◽

Initial Exposure ◽

Antibody Levels ◽

The Impact

Background: During early life, systemic protection to influenza is passively provided by transplacental transfer of IgG antibodies and oral and gastrointestinal mucosal protection via breast milk (BM) containing predominantly IgA. Immune imprinting, influenced by initial exposure of the infant immune system to influenza, has recently been recognized as an important determinant of future influenza immune responses. Methods: We utilized stored frozen BM from a prospective birth cohort to assess immune factors in human milk. The earliest available BM and a paired, timed serum sample was assessed from each of 7 mothers. Paired infant serum samples were assayed at up to three time points during the first 12 months of life, one prior to assumed disappearance of transplacentally transferred IgG, and one after. We utilized a novel multiplex assay to assess mothers’ and infants’ IgG and IgA antibodies in serum to a panel of 30 individual recombinant hemagglutinin (rHA) proteins of influenza virus strains and chimeric rHAs. We also characterized IgA and IgG antibody levels in breast milk which provide mucosal protection. Results: Our pilot results, analyzing a small number of samples demonstrate the feasibility of this method for studying paired maternal-infant IgG and IgA anti-influenza immunity patterns. Unlike IgG antibodies, breast milk influenza virus HA-specific IgA antibody levels and patterns were mostly discordant compared to serum. As expected, there was a steady decay of infant influenza specific IgG levels by 6 to 8 months of age, which was not, however, comparable in all infants. In contrast, most of the infants showed an increase in IgA responses throughout the first year of life Conclusions: This new analytical method can be applied in a larger study to understand the impact of maternal imprinting on influenza immunity.

Download Full-text

Assessment of S1, S2 and NCP-specific IgM, IgA, and IgG antibody kinetics in acute SARS-CoV-2 infection by a microarray and twelve other immunoassays

Journal of Clinical Microbiology ◽

10.1128/jcm.02890-20 ◽

2021 ◽

Author(s):

Georg Semmler ◽

Marianna Theresia Traugott ◽

Marianne Graninger ◽

Wolfgang Hoepler ◽

Tamara Seitz ◽

...

Keyword(s):

Rapid Test ◽

Tracheal Aspirate ◽

Target Antigen ◽

Igg Antibodies ◽

Igg Antibody ◽

Detection Rates ◽

Specific Igg ◽

Antibody Levels ◽

Antibody Kinetics ◽

Specific Igg Antibodies

In this study, we comprehensively analyzed multispecific antibody kinetics of different immunoglobulins in hospitalized patients with acute SARS-CoV-2 infection. Three-hundred-fifty-four blood samples longitudinally obtained from 81 IgG seroconverting CoVID-19 patients were quantified for spike (S)1, S2, and nucleocapsid protein (NCP)- specific IgM, IgA, IgG, and total Ig antibodies using a microarray, eleven different ELISAs/CLIAs, and one rapid test by seven manufacturers. The assays’ specificity was assessed in 130 non-CoVID19 pneumonia patients. Using the microarray, NCP-specific IgA and IgG antibodies continuously displayed higher detection rates during acute CoVID-19 than S1- and S2-specific ones. S1-specific IgG antibodies, however, reached higher peak values. Until the 26th-day post symptom onset, all patients developed IgG responses against S1, S2, and NCP, respectively. Although detection rates by ELISAs/CLIAs generally resembled those of the microarray, corresponding to the target antigen, sensitivities and specificities varied among all tests. Notably, patients with more severe CoVID-19 displayed higher IgG and IgA levels, but this difference was mainly observed with S1-specific immunoassays. In patients with high SARS-CoV-2 levels in the lower respiratory tract, we observed high detection rates of IgG and total Ig immunoassays with a particular rise of S1-specific IgG antibodies when viral concentrations in the tracheal aspirate subsequently declined over time. In summary, our study demonstrates that differences in sensitivity among commercial immunoassays during acute SARS-CoV-2 infection are only partly related to the target antigen. Importantly, our data indicate that NCP-specific IgA and IgG antibodies are detected earlier, while higher S1-specific IgA antibody levels occur in severely ill patients.

Download Full-text

Large-scale study of antibody titer decay following BNT162b2 mRNA vaccine or SARS-CoV-2 infection

10.1101/2021.08.19.21262111 ◽

2021 ◽

Author(s):

Ariel Israel ◽

Yotam Shenhar ◽

Ilan Green ◽

Eugene Merzon ◽

Avivit Golan-Cohen ◽

...

Keyword(s):

Large Scale ◽

Immune Protection ◽

Igg Antibodies ◽

Igg Antibody ◽

Exponential Decrease ◽

Previous Infection ◽

History Of ◽

Antibody Titers ◽

Antibody Levels ◽

Kinetics Of

Background: Immune protection following either vaccination or infection with SARS-CoV-2 decreases over time. Objective: To determine the kinetics of SARS-CoV-2 IgG antibodies following administration of two doses of BNT162b2 vaccine, or SARS-CoV-2 infection in unvaccinated individuals. Methods: Antibody titers were measured between January 31, 2021, and July 31, 2021 in two mutually exclusive groups: i) vaccinated individuals who received two doses of BNT162b2 vaccine and had no history of previous infection with COVID-19 and ii) SARS-CoV-2 convalescents who had not received the vaccine. Results: A total of 2,653 individuals fully vaccinated by two doses of vaccine during the study period and 4,361 convalescent patients were included. Higher SARS-CoV-2 IgG antibody titers were observed in vaccinated individuals (median 1581 AU/mL IQR [533.8-5644.6]) after the second vaccination, than in convalescent individuals (median 355.3 AU/mL IQR [141.2-998.7]; p<0.001). In vaccinated subjects, antibody titers decreased by up to 40% each subsequent month while in convalescents they decreased by less than 5% per month. Six months after BNT162b2 vaccination 16.1% subjects had antibody levels below the seropositivity threshold of <50 AU/mL, while only 10.8% of convalescent patients were below <50 AU/mL threshold after 9 months from SARS-CoV-2 infection. Conclusions: This study demonstrates individuals who received the Pfizer-BioNTech mRNA vaccine have different kinetics of antibody levels compared to patients who had been infected with the SARS-CoV-2 virus, with higher initial levels but a much faster exponential decrease in the first group.

Download Full-text