Specific Immunoglobulin G Antibodies Research Articles

The Development of Toxoplasma gondii Recombinant Trivalent Chimeric Proteins as an Alternative to Toxoplasma Lysate Antigen (TLA) in Enzyme-Linked Immunosorbent Assay (ELISA) for the Detection of Immunoglobulin G (IgG) in Small Ruminants.

This study presents an evaluation of seventeen newly produced recombinant trivalent chimeric proteins (containing the same immunodominant fragment of SAG1 and SAG2 of Toxoplasma gondii antigens, and an additional immunodominant fragment of one of the parasite antigens, such as AMA1, GRA1, GRA2, GRA5, GRA6, GRA7, GRA9, LDH2, MAG1, MIC1, MIC3, P35, and ROP1) as a potential alternative to the whole-cell tachyzoite lysate (TLA) used in the detection of infection in small ruminants. These recombinant proteins, obtained by genetic engineering and molecular biology methods, were tested for their reactivity with specific anti-Toxoplasma IgG antibodies contained in serum samples of small ruminants (192 samples of sheep serum and 95 samples of goat serum) using an enzyme-linked immunosorbent assay (ELISA). The reactivity of six recombinant trivalent chimeric proteins (SAG1-SAG2-GRA5, SAG1-SAG2-GRA9, SAG1-SAG2-MIC1, SAG1-SAG2-MIC3, SAG1-SAG2-P35, and SAG1-SAG2-ROP1) with IgG antibodies generated during T. gondii invasion was comparable to the sensitivity of TLA-based IgG ELISA (100%). The obtained results show a strong correlation with the results obtained for TLA. This suggests that these protein preparations may be a potential alternative to TLA used in commercial tests and could be used to develop a cheaper test for the detection of parasite infection in small ruminants.

Immunoglobulin G (IgG) specific responses to recombinant Qβ displayed MSP3 and UB05 in plasma of asymptomatic Plasmodium falciparum-infected children living in two different agro-ecological settings of Cameroon.

in areas with intense perennial malaria transmission, limited data is available on the impact of environmental conditions especially rainfall on naturally acquired immunity against promising malaria vaccine candidates. For this reason, we have compared IgG antibody responses specific to Plasmodium spp. derived MSP3 and UB05 vaccine candidates, in plasma of children living in two areas of Cameroon differing in rainfall conditions. data about children less than 5 years old was collected during the years 2017 and 2018. Next malaria asymptomatic P. falciparum (Pf) infected children were selected following malaria test confirmation. MSP3 and UB05 specific IgG antibody responses were measured in participant´s plasma using enzyme-linked immunosorbent assay (ELISA). interestingly, IgG antibody responses specific to UB05 were significantly higher (p<0.0001) in Pf-negative children when compared to their asymptomatic Pf-infected counterparts living in monomodal rainfall areas. In contrast, a significantly higher (p<0.0001) IgG response to MSP3 was observed instead in asymptomatic Pf-infected children in the same population. In addition, IgG responses specific to UB05 remained significantly higher in bimodal when compared to monomodal rainfall areas irrespective of children´s Pf infection status (p<0.0055 for Pf-positive and p<0.0001 for negative children). On the contrary, IgG antibody responses specific to MSP3 were significantly higher in bimodal relative to monomodal rainfall areas (P<0.0001) just for Pf-negative children. thus IgG antibody responses specific to UBO5 are a better correlate of naturally acquired immunity against malaria in Pf-negative Cameroonian children especially in monomodal rainfall areas.

IdeS, a secreted proteinase of Streptococcus pyogenes, is bound to a nuclease at the bacterial surface where it inactivates opsonizing IgG antibodies

The important bacterial pathogen Streptococcus pyogenes secretes IdeS (immunoglobulin G-degrading enzyme of S.pyogenes), a proteinase that cleaves human immunoglobulin G (IgG) antibodies in the hinge region resulting in Fc (fragment crystallizable) and F(ab')2 (fragment antigen-binding) fragments and protects the bacteria against phagocytic killing. Experiments with radiolabeled IdeS and flow cytometry demonstrated that IdeS binds to the surface of S.pyogenes, and the interaction was most prominent in conditions resembling those in the pharynx (acidic pH and low salt), the habitat for S.pyogenes. SpnA (S. pyogenes nuclease A) is a cell wall-anchored DNase. A dose-dependent interaction between purified SpnA and IdeS was demonstrated in slot binding and surface plasmon resonance spectroscopy experiments. Gel filtration showed that IdeS forms proteolytically active complexes with SpnA in solution, and super-resolution fluorescence microscopy revealed the presence of SpnA-IdeS complexes at the surface of S.pyogenes. Finally, specific IgG antibodies binding to S.pyogenes surface antigens were efficiently cleaved by surface-associated IdeS. IdeS is secreted by all S.pyogenes isolates and cleaves IgG antibodies with a unique degree of specificity and efficiency. These properties and the finding here that the proteinase is present and fully active at the bacterial surface in complex with SpnA implicate an important role for IdeS in S.pyogenes biology and pathogenesis.

Mucosal humoral immune response of respiratory tract in medical workers during the post-COVID-19 period

Currently, the role of local respiratory tract immunoglobulins in COVID-19 and rearrangement of mucosal immune response in the post-COVID period have not been sufficiently studied. Our aim was to evaluate long-term effects of novel coronavirus infection on the mucosal immunity in healthcare workers over the post-infection period.&#x0D; A total of 180 healthcare workers, ranging in age from 18 to 65 years, were enrolled in a one-stage, cross-sectional study. The subjects with a history of COVID-19 were divided into three groups, depending on the severity of their disease. The control group consisted of 44 healthcare workers who had no history of novel coronavirus infection. Secretory immunoglobulin A (sIgA) and total immunoglobulin G (IgG) levels were quantified in saliva samples, induced sputum samples, naso- and oropharyngeal scrapings by ELISA technique. Specific anti-SARS-CoV-2 IgG antibodies were quantified in the serum by chemiluminescence immunoassay.&#x0D; Numerous shifts in adaptive immune response were detected for different mucosal compartments, i.e., in subjects who suffered from severe or moderate-to-severe COVID-19, salivary sIgA levels were significantly higher than those in the control group (p 0.05 and p 0.005, respectively). An inverse correlation was demonstrated between the levels of total sIgA in all mucosal sites, and the number of days from the onset of disease to the start of study (r = 0.278, р 0.05). When compared to the control subjects, all the patients with prior COVID-19 had significantly higher levels of total IgG in the induced sputum samples. Total IgG in saliva was also higher in the group of patients who had severe infection (p 0.05). By contrast, IgG levels in nasopharyngeal samples were decreased in severe and moderately severe groups compared to the control group, thus, probably, indicating an immunodeficiency state in these cases. A direct significant correlation was also detected between the levels of total IgG in all studied samples and the levels of specific IgG antibodies against SARS-CoV-2 in the serum.&#x0D; Long-term changes in the humoral mucosal immune response were most pronounced in the healthcare workers with a history of severe or moderate-to-severe COVID-19.

Mucosal immunity in health care workers’ respiratory tracts in the post-COVID-19 period

Coronavirus disease (COVID-19) has generated interest in the assessment of systemic immune status, but existing knowledge about mucosal immunity is clearly insufficient to understand the full pathogenetic mechanisms of the disease. The aim of this study was to evaluate the long-term effects of novel coronavirus infection on mucosal immunity in the postinfection period among health care workers (HCWs). A total of 180 health care workers with and without a history of COVID-19 who ranged in age from 18 to 65 years were enrolled in this one-stage, cross-sectional study. The study subjects completed the 36-Item Short Form (36) Health Survey (SF-36) and the Fatigue Assessment Scale. Secretory immunoglobulin A (sIgA) and total immunoglobulin G (IgG) levels were quantified in saliva samples, induced sputum samples, and nasopharyngeal and oropharyngeal scrapings by an enzyme-linked immunosorbent assay. Specific anti-SARS-CoV-2 IgG antibodies were quantified in serum samples by chemiluminescence immunoassay. Analysis of the questionnaire data showed that all HCWs with a history of COVID-19 reported health problems that limited their daily activities and negative changes in their emotional health three months after the disease, regardless of its severity. The following shifts were detected in the adaptive arm of the immune response in different mucosal compartments. Among subjects who had severe or moderate-to-severe COVID-19, salivary sIgA levels were significantly higher than those in the control group (p < 0.05 and p < 0.005, respectively). Compared to the subjects in the control group, all subjects with prior COVID-19 had significantly higher levels of total IgG in induced sputum. In the group of patients who had had severe infection, total IgG in saliva was also higher (p < 0.05). A direct statistically significant correlation was also detected between the levels of total IgG in all studied samples and the levels of specific IgG antibodies against SARS-CoV-2 in the serum. A significant correlation was observed between total IgG levels and the parameters of physical and social activities, mental health, and fatigue levels. Our study demonstrated long-term changes in the humoral mucosal immune response, which were most pronounced in health care workers with a history of severe or moderate-to-severe COVID-19, and an association of these changes with certain clinical signs of post-COVID-19 syndrome.

Specific microRNA Signature Kinetics in Porphyromonas gingivalis-Induced Periodontitis.

Porphyromonas gingivalis is one of the major bacteria constituting the subgingival pathogenic polymicrobial milieu during periodontitis. Our objective is to determine the global microRNA (miRNA, miR) expression kinetics in 8- and 16-weeks duration of P. gingivalis infection in C57BL/6J mice and to identify the miRNA signatures at specific time-points in mice. We evaluated differential expression (DE) miRNAs in mandibles (n = 10) using high-throughput NanoString nCounter® miRNA expression panels. The bacterial colonization, alveolar bone resorption (ABR), serum immunoglobulin G (IgG) antibodies, and bacterial dissemination were confirmed. In addition, all the infected mice showed bacterial colonization on the gingival surface, significant increases in ABR (p < 0.0001), and specific IgG antibody responses (p < 0.05-0.001). The miRNA profiling showed 26 upregulated miRNAs (e.g., miR-804, miR-690) and 14 downregulated miRNAs (e.g., miR-1902, miR-1937a) during an 8-weeks infection, whereas 7 upregulated miRNAs (e.g., miR-145, miR-195) and one downregulated miR-302b were identified during a 16-weeks infection. Both miR-103 and miR-30d were commonly upregulated at both time-points, and all the DE miRNAs were unique to the specific time-points. However, miR-31, miR-125b, miR-15a, and miR-195 observed in P. gingivalis-infected mouse mandibles were also identified in the gingival tissues of periodontitis patients. None of the previously identified miRNAs reported in in vitro studies using cell lines (periodontal ligament cells, gingival epithelial cells, human leukemia monocytic cell line (THP-1), and B cells) exposed to P. gingivalis lipopolysaccharide were observed in the in vivo study. Most of the pathways (endocytosis, bacterial invasion, and FcR-mediated phagocytosis) targeted by the DE miRNAs were linked with bacterial pathogen recognition and clearance. Further, eighteen miRNAs were closely associated with the bacterial invasion of epithelial cells. This study highlights the altered expression of miRNA in gingiva, and their expression depends on the time-points of infection. This is the first in vivo study that identified specific signature miRNAs (miR-103 and miR-30d) in P. gingivalis invasion of epithelial cells, establishes a link between miRNA and development of periodontitis and helping to better understand the pathobiology of periodontitis.

The SARS-CoV-2 specific IgG antibodies biophotonic sensor.

In this paper, we present the design and the principle of operation of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specific immunoglobulin G (IgG) biophotonic sensor, which is based on the single-mode telecommunication fiber. We fabricated the sensor head at the face of the single mode fiber-28. Due to the process of bio-functionalization, our sensor has the ability to selectively detect the SARS-CoV-2 specific IgG antibodies. The results of preliminary tests allowed us to correctly determine the presence of antibodies in less than 1 min in 5 μl in a volume sample of concentration of 10 μg/ml, which according to studies, corresponds to the concentration of IgG antibodies in human serum. Additionally, the tested sample can be smaller than 5 μl in volume.

An Immune Response to Heterologous ChAdOx1/BNT162b2 Vaccination against COVID-19: Evaluation of the anti-RBD Specific IgG Antibodies Titers and Interferon Gamma Release Assay (IGRA) Test Results

This study aimed to assess the magnitude of anti-SARS-CoV-2 immunoglobulin G (IgG) titers and Interferon-Gamma Release Assay (IGRA) test results following administration of booster BNT162b2 in 48 ChAd-primed participants (vaccination schedule: ChAd/ChAd/BNT). Whole blood samples were collected: first, before and second, 21 days after the booster dose. The IgG level was measured using chemiluminescent immunoassay; the intensity of the T-cell response—IFNγ concentration—was assessed using IGRA test. At 21 days after the booster, all subjects achieved reactive/positive anti-SARS-CoV-2 IgG, and IGRA test results showed a significant increase compared to the results before booster administration. We compared the results before and after the booster between participants with and without prior history of COVID-19. The IFNγ concentrations in both cohorts were higher in convalescents (both before booster and 21 days after). The IgG titers were subtly lower in COVID-19 convalescents than in naïve but without statistical significance. Data on cell-mediated immunity are scarce, especially with regard to the general population. A better understanding of the complexity of the immune response to SARS-CoV-2 could contribute to developing more effective vaccination strategies.

Maternal gut microbiome-induced IgG regulates neonatal gut microbiome and immunity.

The gut microbiome elicits antigen-specific immunoglobulin G (IgG) at steady state that cross-reacts to pathogens to confer protection against systemic infection. The role of gut microbiome-specific IgG antibodies in the development of the gut microbiome and immunity against enteric pathogens in early life, however, remains largely undefined. In this study, we show that gut microbiome-induced maternal IgG is transferred to the neonatal intestine through maternal milk via the neonatal Fc receptor and directly inhibits Citrobacter rodentium colonization and attachment to the mucosa. Enhanced neonatal immunity against oral C. rodentium infection was observed after maternal immunization with a gut microbiome-derived IgG antigen, outer membrane protein A, or induction of IgG-inducing gut bacteria. Furthermore, by generating a gene-targeted mouse model with complete IgG deficiency, we demonstrate that IgG knockout neonates are more susceptible to C. rodentium infection and exhibit alterations of the gut microbiome that promote differentiation of interleukin-17A-producing γδ T cells in the intestine, which persist into adulthood and contribute to increased disease severity in a dextran sulfate sodium-induced mouse model of colitis. Together, our studies have defined a critical role for maternal gut microbiome-specific IgG antibodies in promoting immunity against enteric pathogens and shaping the development of the gut microbiome and immune cells in early life.

Seroprevalence of TORCH Syndrome Among Women of Reproductive Age in Mashhad, Northeast of Iran

Aims TORCH syndrome is responsible for 2% to 3% of all congenital anomalies caused by Toxoplasma gondii (T. gondii), rubella virus (RV), cytomegalovirus (CMV), and herpes simplex virus (HSV). The current study aims to determine the prevalence of TORCH infection in women in Mashhad City, Iran. Methods &amp; Materials This cross-sectional study was conducted on 417 patients who were referred to 3 laboratories in Mashhad City, Iran. The laboratory data were collected from ​April 2016 to March 2020 to detect the specific immunoglobulin G (IgG) and immunoglobulin M (IgM) against the TORCH syndrome. Findings The specific IgG antibodies were found to be positive for CMV in 402 cases (96.4%), RV in 394 cases (94.5%), and T. gondii in 80 cases (19.2%). Moreover, 7 (1.6%) of the participants were found to be positive for anti-CMV IgM, 6 (1.4%) for anti-IgM RV, and 8 (1.9%) for anti-IgM T. gondii. In addition, the relationship between age and anti-T. gondii IgG in the age group of 37-47 years was 6. 44 times higher than the age group of 17-27 years. The relationship between age and anti-CMV IgG in the age group of 27-37 years was 4.13 times higher than in the age group of 37-47 years. Conclusion All women in their reproductive age should be regularly screened for TORCH syndrome to prevent congenital TORCH syndrome.

Humoral response to Plasmodium falciparum antigenic peptides (MSP1, MSP2, and SR-11.1) in subjects living in endemic areas

Introductionles vaccins constituent les outils privilégiés pour le contrôle et l´éradication du paludisme dans le monde. Actuellement, la recherche et développement est orientée vers trois types de candidats vaccins qui ciblent différents stades de vie du Plasmodium falciparum chez l´homme et le vecteur. L´objectif est d´évaluer la réponse humorale contre les peptides antigéniques de Plasmodium falciparum (MSP1, MSP2 et SR-11.1) chez des sujets vivant en zone endémique.Méthodesnous avons réalisé une étude transversale sur une période de 5 mois portant sur les sérums de 182 sujets Vietnamien vivant dans les aires endémiques. Le sang total a été centrifugé et, le sérum aliquoté dans des cryotubes et conservé à -20°C pour le dosage des immunoglobulines G (IgG). Le dosage des immunoglobulines G totales a été réalisé par la technique ELISA après couplage des peptides avec le glutaraldéhyde.Résultatsau total, 182 sérums de sujets Vietnamiens vivant en zone endémique ont été inclus. Dans les différentes tranches d´âges d´études, les IgG totales spécifiques contre les peptides antigéniques (MSP-1; MSP-2 et SR-11.1) de P. falciparum montrent une répartition âge dépendant. Chez les sujets de 3 à 19 ans, le taux des IgG totales spécifiques contre Plasmodium falciparum est moins élevé par rapport à celui des groupes d´âge de plus de 20 ans (p=0.07). La comparaison des taux d´IgG spécifiques contre les peptides antigéniques MSP-1, MSP-2 et SR-11.1 du P. falciparum dans les groupes d´âge, donne une moyenne significativement plus élevée pour MSP-1 et MSP-2 par rapport au taux d´anticorps anti-SR-11.1 (p=0.04).Conclusionnous avons trouvé que le taux des anticorps spécifiques contre les peptides antigéniques (MSP-1; MSP-2 et SR-11.1) de P. falciparum est âge dépendant. Des trois peptides antigéniques, MSP-1 et MSP-2 apparaissent plus immunogènes que SR.11.1. Donc, SR.11.1 est une macromolécule pour le système immunitaire et de ce point de vue apparait nettement moins immunogène que les autres peptides.

Sustained seroprevalence of SARS-CoV-2 antibodies one year after infection: one of the first COVID-19 cluster cases in Bosnia and Herzegovina.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is a novel virus that has been identified as a causal agent of COVID-19, an emergent infectious disease which brought about a new pandemic in the 21st century. The immune responses and clinical features of individuals infected with SARS-CoV-2 have not yet been fully described. Thus, in this study, we compare the seroprevalence and define the correlation between symptoms and serological results in the first COVID-19 cluster in the city of Konjic, Bosnia, and Herzegovina. Of the total number, 93% of real-time polymerase chain reaction-positive participants had positive immunoglobulin G (IgG) serology and 75% of them developed symptoms of COVID-19. We found that there was no significant alteration in specific IgG (p = 0.504) antibody levels during the 1-year period after COVID-19. Our results indicate that symptomatic COVID-19 patients have a higher rate of seroconversion (p < 0.01). The IgG seroconversion was correlated with high fever (p = 0.002) and headache (p = 0.007), suggesting that these symptoms could be considered as indicators of a better immune response. This study has demonstrated persistence of sustained levels of specific SARS-CoV-2 antibodies after recovering from COVID-19 infection. However, to gain a better insight into the immune response to SARS-CoV-2, further systematic studies should be focused on quality and longevity analyses.

Development of SARS-CoV-2 Specific IgG and Virus-Neutralizing Antibodies after Infection with Variants of Concern or Vaccination.

The humoral immunity after SARS-CoV-2 infection or vaccination was examined. Convalescent sera after infection with variants of concern (VOCs: B.1.1.7, n = 10; B.1.351, n = 1) and sera from 100 vaccinees (Pfizer/BioNTech, BNT162b2, n = 33; Moderna, mRNA-1273, n = 11; AstraZeneca, ChAdOx1 nCoV-19/AZD1222, n = 56) were tested for the presence of immunoglobulin G (IgG) directed against the viral spike (S)-protein, its receptor-binding domain (RBD), the nucleoprotein (N) and for virus-neutralizing antibodies (VNA). For the latter, surrogate assays (sVNT) and a Vero-cell based neutralization test (cVNT) were used. Maturity of IgG was determined by measuring the avidity in an immunoblot (IB). Past VOC infection resulted in a broad reactivity of anti-S IgG (100%), anti-RBD IgG (100%), and anti-N IgG (91%), while latter were absent in 99% of vaccinees. Starting approximately two weeks after the first vaccine dose, anti-S IgG (75–100%) and particularly anti-RBD IgG (98–100%) were detectable. After the second dose, their titers increased and were higher than in the convalescents. The sVNT showed evidence of VNA in 91% of convalescents and in 80–100%/100% after first/second vaccine dose, respectively. After the second dose, an increase in VNA titer and IgGs of high avidity were demonstrated by cVNT and IB, respectively. Re-vaccination contributes to a more robust immune response.

Establishment and verification of a quantitative ELISA assay for detection of human serotype specific IgG against Streptococcus pneumoniae

Objective To establish a quantitative enzyme-linked immunosobent assay (ELISA) recommended by World Health Organization (WHO) for the detection of human serotype specific immunoglobulin G (IgG) against Streptococcus pneumoniae (Sp). Methods According to WHO′s operation manual for Enzyme linked immunosobent assay ELISA for the quantitative of Streptococcus pneumoniae serotype specific IgG (Pn PS ELISA), we established a ELISA method to detect serotype specific IgG against Sp in human serum specimens by using Sp capsular polysaccharide 4, 6B, 9V, 14, 18C, 19F, and 23F (purchased American Type Culture Collection, ATCC) as coating antigens and pneumococcal capsular polysaccharide antibody standard serum 007 sp (from National Institute for Biological Standards and Control, NIBSC) as standard serum. The accuracy and stability of the established method were evaluated using WHO′s calibration serum panel and internal quality control serum PnG. Results The concentration of 7 serotype specific coating antigens of Sp capsular polysaccharide (4, 6b, 9V, 14, 18C、19F and 23F) were determined and serotype specific IgG against Sp in human serum specimens were detected with the quantitative ELISA method established. More than 75% of measurements for 7 serotype specific Sp capsular polysaccharide IgG antibodies for 12 WHO calibration sera were within ± 40% of the measurement values assigned by reference laboratories of WHO, with an overall consistency rate of 86.9%, a correlation curve slope of 0.94, and an R2 of 0.99, respectively. In addition, the results of 20 consecutive internal quality control serum test showed that the coefficient of variation (CV) of different batches were less than 15%, which met the requirements of WHO intra-laboratory evaluation. Conclusion A quantitative ELISA method recommended by WHO for detection of serotype-specific Streptococcus pneumoniae IgG antibody in human serum was successfully established and verified. The accurate and stable method meet the requirements of disease surveillance and vaccine effect evaluation.

Multiplex quantitative detection of SARS-CoV-2 specific IgG and IgM antibodies based on DNA-assisted nanopore sensing

The coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread into a global pandemic. Early and accurate diagnosis and quarantine remain the most effective mitigation strategy. Although reverse transcriptase polymerase chain reaction (RT-qPCR) is the gold standard for COVID-19 diagnosis, recent studies suggest that nucleic acids were undetectable in a significant number of cases with clinical features of COVID-19. Serologic assays that detect human antibodies to SARS-CoV-2 serve as a complementary method to diagnose these cases, as well as to identify asymptomatic cases and qualified convalescent serum donors. However, commercially available enzyme-linked immunosorbent assays (ELISA) are laborious and non-quantitative, while point-of-care assays suffer from low detection accuracy. To provide a serologic assay with high performance and portability for potential point-of-care applications, we developed DNA-assisted nanopore sensing for quantification of SARS-CoV-2 related antibodies in human serum. Different DNA structures were used as detection reporters for multiplex quantification of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against the nucleocapsid protein of SARS-CoV-2 in serum specimens from patients with conformed or suspected infection. Comparing to a clinically used point-of-care assay and an ELISA assay, our technology can reliably quantify SARS-CoV-2 antibodies with higher accuracy, large dynamic range, and potential for assay automation.

Persistence of Antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 in Relation to Symptoms in a Nationwide Prospective Study.

BackgroundAssessing the duration of immunity following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a first priority to gauge the degree of protection following infection. Such knowledge is lacking, especially in the general population. Here, we studied changes in immunoglobulin isotype seropositivity and immunoglobulin G (IgG) binding strength of SARS-CoV-2–specific serum antibodies up to 7 months following onset of symptoms in a nationwide sample.MethodsParticipants from a prospective representative serological study in the Netherlands were included based on IgG seroconversion to the spike S1 protein of SARS-CoV-2 (N = 353), with up to 3 consecutive serum samples per seroconverted participant (N = 738). Immunoglobulin M (IgM), immunoglobulin A (IgA), and IgG antibody concentrations to S1, and increase in IgG avidity in relation to time since onset of disease symptoms, were determined.ResultsWhile SARS-CoV-2–specific IgM and IgA antibodies declined rapidly after the first month after disease onset, specific IgG was still present in 92% (95% confidence interval [CI], 89%–95%) of the participants after 7 months. The estimated 2-fold decrease of IgG antibodies was 158 days (95% CI, 136–189 days). Concentrations were sustained better in persons reporting significant symptoms compared to asymptomatic persons or those with mild upper respiratory complaints only. Similarly, avidity of IgG antibodies for symptomatic persons showed a steeper increase over time compared with persons with mild or no symptoms (P = .022).ConclusionsSARS-CoV-2–specific IgG antibodies persist and show increasing avidity over time, indicative of underlying immune maturation. These data support development of immune memory against SARS-CoV-2, providing insight into protection of the general unvaccinated part of the population.Clinical Trials RegistrationNL8473 (the Dutch trial registry).

Bioengineering of Virus-like Particles for the Prevention or Treatment of Allergic Diseases.

Recent findings on the mechanism of allergen-specific immunotherapy (AIT) have revisited the role of immunoglobulin G (IgG) as the development of specific blocking IgG antibodies appeared critical for the successful suppression of T-helper 2 (Th2)-biased allergic responses. Consequently, any form of molecular AIT-promoting potent allergen-specific neutralizing antibodies would be preferred to conventional administration of allergen extracts. The potent immunogenicity of virus-like particles (VLPs) could be harnessed for that purpose. The particle size (20–200 nm) optimizes uptake by antigen-presenting cells as well as lymphatic trafficking. Moreover, the display of antigens in repetitive arrays promotes potent B cell activation for the development of sustained antibody responses. The presentation of self-antigens on the particle surface was even capable to break B cell tolerance. In this review, we describe the immunomodulatory properties of the 3 VLP-based strategies designed so far for the treatment of allergic disease: VLP packaged with CpG motifs as well as chimeric particles displaying pro-Th2/Th2 cytokines or allergens (full-length or B cell epitopes).

Serum IgG Profile in Convalescent COVID-19 Patients in Different ABO Blood Grouping System: A Retrospective Study

Introduction: The plasma collected from the recovered Coronavirus Disease 2019 (COVID-19) patients is used therapeutically in serious COVID-19 patients as a life saving procedure. Serum Immunoglobulin G (IgG) estimation is a routine procedure followed in these voluntary donors. In this routine procedure, authors have come across patients with particular blood group having more chances of seronegativity for COVID-19 IgG antibody. This is the reason why the present study was conducted. Aim: To find out the variable IgG response in recovered COVID- 19 patients with different types of clinical manifestations along with the possible relation with different types of blood groups of ABO system. Materials and Methods: This retrospective study was conducted in plasma bank of Veer Surendra Sai Institute of Medical Science and Research, Burla, Odisha, India, from 1st August to 15th December 2020. Severe Acute Respiratory Syndrome Coronavirus-2 (SARS- CoV-2) specific IgG antibody level was estimated quantitatively using Chemiluminescence Immunoassay (CLIA) method. Patients with IgG level more than 1.4 were taken as positive. Results: This study had estimated IgG level during screening of 440 voluntary plasma donors. Out of these, seropositivity was found in 354 patients. Patients with blood group O and AB were having seropositivity rate more than that of other ABO blood groups, whereas seronegativity percentage was more in blood group A patients. Conclusion: There was a non specific relation between severity of symptoms and detectable development of IgG antibody in recovered corona patients. Also, blood group A patients develop less likely IgG antibody against COVID-19.

Seroprevalence of Toxoplasmosis Among Pregnant Women Attending Antenatal Care in Asmara, Eritrea: Preliminary Report

Introduction: The majority of human infections with Toxoplasma gondii produce no symptoms, but in congenitally infected children can cause devastating effects including blindness, brain damage, or miscarriage. Transmission to the fetus occurs predominantly in women who acquire their primary infection during gestation. The study aimed to assess the seroprevalence of toxoplasmosis among pregnant women attending antenatal care (ANC) in different areas of Asmara, Eritrea, and to identify possible risk factors associated with toxoplasmosis among pregnant women attending the ANC centers. Methods: In this cross-sectional laboratory-based study, the data were collected from 210 pregnant women in four health facilities. Voluntary sampling technique and a structured questionnaire were used to collect the associated data and socio-demographic information. Cobas e411 Analyzer was used to test the blood serum for immunoglobulin G (IgG) and Immunoglobulin M (IgM) antibodies. Epi-Info version 7.0 was used for data entry and SPSS version 20.0 was used for data analysis. Results: Of the 210 samples, 112 (53.6%) samples were seropositive and 97 (46.4%) samples were seronegative for T. gondii specific IgG antibody. Furthermore, 2.9% (6) of the samples were seropositive and 97.1% (203) of the samples were seronegative for T. gondii-specific IgM antibodies. Conclusion: The seroprevalence was considerably high, 53.6% for IgG antibody and 2.9% for IgM antibody, which require attention in order to implement preventive control measures, screening tests, and health education.

Seroprevalence And Risk Factors of Specific Toxoplasma Gondii Antibody among Pregnant Women

Toxoplasmosis during pregnancy has an adverse effect on pregnant women, fetus and neonatal. The infection is generally asymptomatic but can cause severe effect on the fetus and immunocompromised women. Control study conducted on 77 pregnant women categorized according to the risk factors influencing toxoplasmosis infection. Specific anti Toxoplasma gondii IgG and IgM were evaluated using Enzyme-linked immunosorbent assay (ELISA) test kits. Among 77 pregnant women, (57.1%) women had toxoplasmosis, seropositive for latent infection with specific Toxoplasma gondii immunoglobulin G (IgG) antibodies were (54.54 %), whereas acute infection immunoglobulin M (IgM) were only in (2.59 %) cases. The seroprevalence of Toxoplasma was higher in older pregnant women (&gt; 60%) than younger ones (&lt;50%). The specific IgG antibody was higher in pregnant women working in farms (65.7 vs 45.23; P=0.053). Also, the seropositive IgG antibody was low in the first trimester and high in rural areas. Pregnant women need to educate more about toxoplasmosis and prevention to exposure in order to reduce the risk of congenital toxoplasmosis.