Immunoglobulin Type G Research Articles

Determinants of Systemic SARS-CoV-2-Specific Antibody Responses to Infection and to Vaccination: A Secondary Analysis of Randomised Controlled Trial Data.

SARS-CoV-2 infections elicit antibodies against the viral spike (S) and nucleocapsid (N) proteins; COVID-19 vaccines against the S-protein only. The BCG-Corona trial, initiated in March 2020 in SARS-CoV-2-naïve Dutch healthcare workers, captured several epidemic peaks and the introduction of COVID-19 vaccines during the one-year follow-up. We assessed determinants of systemic anti-S1 and anti-N immunoglobulin type G (IgG) responses using trial data. Participants were randomised to BCG or placebo vaccination, reported daily symptoms, SARS-CoV-2 test results, and COVID-19 vaccinations, and donated blood for SARS-CoV-2 serology at two time points. In the 970 participants, anti-S1 geometric mean antibody concentrations (GMCs) were much higher than anti-N GMCs. Anti-S1 GMCs significantly increased with increasing number of immune events (SARS-CoV-2 infection or COVID-19 vaccination): 104.7 international units (IU)/mL, 955.0 IU/mL, and 2290.9 IU/mL for one, two, and three immune events, respectively (p < 0.001). In adjusted multivariable linear regression models, anti-S1 and anti-N log10 concentrations were significantly associated with infection severity, and anti-S1 log10 concentration with COVID-19 vaccine type/dose. In univariable models, anti-N log10 concentration was also significantly associated with acute infection duration, and severity and duration of individual symptoms. Antibody concentrations were not associated with long COVID or long-term loss of smell/taste.

Immunity transfer in mule foals fed with good IgG quality colostrum

While the passive transfer of immunity in horse and donkey foals has been extensively studied, there is limited information for mule foals. Immunoglobulin type G (IgG) and serum total protein concentration (TP) were assessed at different sampling times to evaluate the correlation between serum radial immunodiffusion (SRID) with electrophoresis, refractometry, and dry chemistry analyzer (Biuret), and to estimate serum IgG concentrations using serum TP in mule foals. We analyzed a total of 30 samples collected at birth, and at 6, 12, 24, and 48 h of life from 6 mule foals by SRID, electrophoresis TP, biuret TP, and refractometry TP.The SRID IgG concentration significantly increased from birth until T6 (p < 0.001). Serum TP analyzed with refractometry revealed differences between T0 and T12, T24 and T48 (p < 0.05), while a significant difference was observed with the biuret method between T0 and all the other sampling times (p < 0.001).A strong correlation was found between IgG SRID and biuret TP (r = 0.69, p < 0.001), and a good correlation existed between IgG SRID, refractometry TP, and electrophoresis TP (r = 0.44, p < 0.01 and r = 0.39, p < 0.05, respectively).All methods can be used to estimate the passive transfer of immunity in mule foals. TP refractometry and biuret TP values can be used to determine serum IgG concentrations in the blood of mule foals on their first day of life through the application of a specific equation.

Evaluation of jennies' colostrum: IgG concentrations and absorption in the donkey foals. A preliminary study

Immunoglobulin type G (IgG) concentration both in jennies' colostrum and in serum of donkey foals are mostly unknown in the first 24 h after delivery. The aims of the present study were to evaluate the IgG concentrations of colostrum during the first 24 h of lactation of Amiata jennies, the absorption of colostrum and the weekly body weight gain of the donkey foals. IgG concentrations were assessed in the jennies' colostrum and in the serum of donkey foals. Colostrum was collected in 9 jennies ready after delivery, and at 6, 12, 24 h after foaling from both halves. Serum was collected at the same sampling times from 9 donkey foals. Donkey foals were weighted at birth and then weekly until the 28th days of life. Temporal changes of IgG concentrations in dam's colostrum and in donkey foal serum were analyzed by a linear regression model and a general linear model, respectively. Results showed that colostrum IgG concentration were similar between the left and the right half. Colostrum IgG concentrations decreased continuously throughout the time in all jennies by 0.0244 Log10 mg/mL per hour. Serum IgG concentrations in donkey foals at birth was significantly lower compared to other times. No correlation was found between the colostrum IgG concentrations and the average weekly body weight gain of the donkey foal. The pattern of colostrum IgG levels in jennies and serum IgG concentration in donkey foals seem to be similar to what reported for equine. However, the donkey foals seem to be less agammaglobulinemic at birth compared to the horse foal. The pattern and both serum and colostrum concentrations evaluated in the Amiata donkeys were slightly different from results reported in other donkey breeds, underlying the importance of setting references specific to breed.

An atomistic perspective on antibody-dependent cellular cytotoxicity quenching by core-fucosylation of IgG1 Fc N-glycans from enhanced sampling molecular dynamics.

The immunoglobulin type G (IgG) Fc N-glycans are known to modulate the interaction with membrane-bound Fc γ receptors (FcγRs), fine-tuning the antibody's effector function in a sequence-dependent manner. Particularly interesting in this respect are the roles of galactosylation, which levels are linked to autoimmune conditions and aging, of core fucosylation, which is known to reduce significantly the antibody-dependent cellular cytotoxicity (ADCC), and of sialylation, which also reduces antibody-dependent cellular cytotoxicity (ADCC) but only in the context of core-fucosylation. In this article, we provide an atomistic level perspective through enhanced sampling computer simulations, based on replica exchange molecular dynamics (REMD), to understand the molecular determinants linking the Fc N-glycans sequence to the observed IgG1 function. Our results indicate that the two symmetrically opposed N-glycans interact extensively through their core trimannose residues. At room temperature, the terminal galactose on the α (1-6) arm is restrained to the protein through a network of interactions that keep the arm outstretched; meanwhile, the α (1-3) arm extends toward the solvent where a terminal sialic acid remains fully accessible. We also find that the presence of core fucose interferes with the extended sialylated α (1-3) arm, altering its conformational propensity and as a consequence of steric hindrance, significantly enhancing the Fc dynamics. Furthermore, structural analysis shows that the core-fucose position within the Fc core obstructs the access of N162 glycosylated FcγRs very much like a "door-stop," potentially decreasing the IgG/FcγR binding free energy. These results provide an atomistic level-of-detail framework for the design of high potency IgG1 Fc N-glycoforms.

Impact of feed restriction and housing hygiene conditions on specific and inflammatory immune response, the cecal bacterial community and the survival of young rabbits

Limiting the post-weaning intake of the young rabbit is known to improve its resistance to digestive disorders, whereas a degradation of its housing hygiene is assumed to have a negative impact on its health. This study aims at providing insights into the mechanism of digestive health preservation regarding both host (growth and immune response) and its symbiotic digestive microbiota. A 2×2 factorial design from weaning (day 28) to day 64 was set up: ad libitum intake or restricted intake at 70% of ad libitum, and high v. low hygiene of housing (n=105 per group). At day 36 and day 45, 15 animals/group were subcutaneously immunized with ovalbumin (OVA) to assess their specific immune response. Blood was sampled at 36, 45, 57 and 64 days of age to determine total and anti-OVA immunoglobulin type G (IgG) and haptoglobin levels. The cecal bacterial community was explored (18 per group) by 454 pyrosequencing of genes coding for the 16S ribosomal RNA, whereas cecal pH, NH3 and volatile fatty acid (VFA) concentrations were measured to characterize fermentative activity. A 30% reduction in feed intake reduced the growth by only 17% (P<0.001), and improved the feed conversion ratio by 15% (P<0.001), whereas the degradation of hygiene conditions slightly decreased the feed intake in ad libitum fed rabbits (−3.5%, P<0.02). As poor hygiene conditions did not affect weight gain, feed conversion was improved from day 42 (P<0.05). Restricted feeding led to a lower mortality between day 28 and day 40 (P=0.047), whereas degraded hygiene conditions decreased overall morbidity (7.8% v. 16.6%; P<0.01). Both a reduced intake and low hygiene conditions of housing affected microbiota composition and especially dominant genera belonging to the Ruminococcaceae family (P<0.01). Moreover, low hygiene was associated with a higher Ruminococcaceae/Lachnospiraceae ratio (3.7 v. 2.4; P<0.05). Cecal total VFA and pH were increased (+19%; P<0.001) and decreased (−0.1 pH unit; P<0.05), respectively, in feed-restricted rabbits. Neither specific anti-OVA IgG nor haptoglobin was affected by treatments. Total IgG concentrations were the highest in animals raised in poor hygiene conditions after 8 days of restriction, but decreased after 19 days of restriction in high hygiene conditions (−2.15%; P<0.05). In conclusion, the degradation of hygiene conditions failed to induce a systematic specific and inflammatory response in rabbit, but reduced morbidity instead. Our results suggest that the microbiota composition would be a helpful source of biomarkers of digestive health.

Proteins and cholesterol lipid vesicles are mediators of drug release from thermosensitive liposomes

Thermosensitive liposomes (TSL) are a promising tool for triggered drug delivery in combination with local hyperthermia. Objective of this study was to investigate the influence of serum on TSL in more detail and to identify serum components which are responsible for increasing drug release. Four different formulations were investigated: DPPC/DSPC/1,2-dipalmitoyl-sn-glycero-3-phosphodiglycerol (DPPG2) 50/20/30 (mol/mol) (DPPG2-TSL); DPPC/DSPC/DPPG2/DSPE-PEG2000 50/15/30/5 (mol/mol) (DPPG2/PEG-TSL), DPPC/P-Lyso-PC/DSPE-PEG2000 90/10/4 (mol/mol) (PEG/Lyso-TSL), and DPPC/DSPC/DSPE-PEG2000 80/15/5 (mol/mol) (PEG-TSL). DPPG2-TSL was the only formulation which was unaffected by osmotic stress. All formulations tested were influenced by serum components but the susceptibility was depended on the lipid composition of the vesicle. Presence of albumin (HSA) or cholesterol-containing lipid vesicles (DPPC/Chol-LLV) increased the membrane permeability for all tested formulations at temperatures around and above Tm in a concentration based manner. PEGylation was not able to prevent the observed effect. PEG-TSL and PEG/Lyso-TSL were more susceptible to DPPC/Chol-LLV than DPPG2-containing TSL. In contrast, immunoglobulin type G (IgG) affected only anionic formulations. The membrane of DPPG2-TSL and DPPG2/PEG-TSL was more susceptible toward IgG as compared to HSA. DPPG2-TSL and PEG/Lyso-TSL were differentially influenced by fetal calf serum (FCS). As DPPG2-TSL was stabilized by pre-incubation with FCS at 37°C, this was the opposite for PEG/Lyso-TSL which were destabilized under these conditions. Individual serum components were unable to mimic the complex situation in full serum. Hence, the use of plasma or serum is still inevitable to investigate stability and release properties of novel TSL formulations until all serum components have been identified that alter TSL integrity.

Exploring variation in binding of Protein A and Protein G to immunoglobulin type G by isothermal titration calorimetry

Bacterial Protein A (PrtA) and Protein G (PrtG) are widely used for affinity purification of antibodies. An understanding of how PrtA and PrtG bind to different isotypes of immunoglobulin type G (IgG) and to their corresponding Fc fragments is essential for the development of PrtA and PrtG mimetic ligands and for the establishment of generic processes for the purification of various antibodies. In this paper, the interactions between the two IgG-binding proteins and IgG of two different subclasses, IgG1 and IgG4, as well as their analogous Fc fragments have been studied by isothermal titration calorimetry. The results indicate that both protein ligands bind IgG and Fc fragments strongly with Ka values in the range of 10(7) -10(8) M(-1) and for both ligands, the interaction with both IgG isotypes is enthalpically driven though entropically unfavorable. Moreover, variation in the standard entropic and standard enthalpic contribution to binding between the two isotypes as well as between IgG and Fc fragment implies that the specific interaction with PrtA varies according to IgG isotype. In contrast to PrtA, PrtG bound to F(ab')(2) fragment with a Ka value of 5.1 × 10(5) M(-1) ; thus underscoring the usefulness of PrtA as a preferred ligand for generic antibody purification processes.

Conditional Expression of Full-Length Humanized Anti-Prion Protein Antibodies in Chinese Hamster Ovary Cells

Because of their high antigen specificity and metabolic stability, genetically engineered human monoclonal antibodies are on the way to becoming one of the most promising medical diagnostics and therapeutics. In order to establish an in vitro system capable of producing such biosimilar antibodies, we used human constant chain sequences to design the novel human antibody expressing vector cassette pMAB-ABX. A bidirectional tetracycline (tet)-controllable promotor was used for harmonized expression of immunoglobulin type G (IgG) heavy and light chains. As an example we used anti-prion protein (anti-PrP) IgGs. Therefore, the variable heavy (V(H)) and light chain (V(L)) sequences of anti-PrP antibodies, previously generated in our laboratory by DNA immunization of prion protein knock-out mice, were isolated from murine hybridoma cell lines and inserted into pMAB-ABX vector. After transfection of Chinese hamster ovary (CHO) cells, a number of stable antibody producing cell clones were selected. One cell line (pMAB-ABX-13F10/3B5) stably expressing the recombinant humanized antibody (rechuAb) 13F10/3B5 was selected for detailed characterization by Western blot, immunofluorescence, and flow cytometric analyses. The full-length recombinant humanized IgG antibody showed a high level of expression in the cytoplasm. In conclusion, the new cell system described here is a suitable tool to produce functional intact full-length humanized IgG antibodies.

Selective Detection of Antigen-Antibody Reaction Using Si Ring Optical Resonators

Si ring optical resonators have been fabricated by the Si LSI technology using electron beam lithography and reactive ion etching. The resonator is applied for sensing receptor-analyte reaction using silicon-binding protein, Si-tag, which enables receptors immobilized on a Si dioxide surface with a controlled orientation. For the receptor, the major house-dust mite allergen called Der f 2 was used, and for the analyte anti-Der f 2 immunoglobulin type G (IgG), which is selectively bound to Der f 2, was used. Antiserum against Der f 2, which contains anti-Der f 2 IgG, was diluted to 1/100 with the pure water, and exposed to the resonator on which the Der f 2 was adsorbed with the Si-tag. Then the resonance wavelength was shifted by 0.18 nm, while exposure of the normal rabbit serum containing no Der f 2 IgG resulted in the peak shift less than half (0.07 nm). These results indicate the selective reaction between Der f 2 and anti-Der f 2 IgG.

Serum immunoglobulin type g concentrations in calves produced by IVF and delivered by elective cesarean section

Colostrum ingestion by neonatal calves is widely recognized to provide passive transfer of immunity. In this study immunoglobulin absorption from colostrum was evaluated in 54 IVF-produced calves. The IVF calves were delivered by Cesarean section on Days 275 to 277 of gestation, 24 h after the dams had been administered 30 mg dexamethasone. The calves suckled bottles or were force-fed 6 L of colostrum in the first 12 h of life. Colostrum was obtained from the first post-calving milking of recipient dams or from frozen storage reserves if dam secretion was not adequate. Immunoglobulin type G (IgG) content of both sources of colostrum was determined. Serum samples from the calves were collected at 0,12 and 24 h of age and analyzed for IgG. Twenty dairy calves born vaginally served as the controls and were subjected to the same colostrum management protocol except that the colostrum was obtained only from frozen post-calving milk of dairy cows from the same farm. The control calves were also subjected to the same sampling protocol. The IVF group of calves ingested more IgG (P<0.0001) and absorbed more IgG by 24 h of age (P<0.0001) than their control group counterparts. Absorption of IgG was analyzed by comparing the g/kg body weight of IgG with serum IgG values at corresponding times after birth. Colostrum absorption efficiency was the same for both IVF and control groups of calves at 12 and 24 h of age. There was a maximum IgG dose above which additional increases in serum IgG were not realized. The slightly premature, Cesarean delivered IVF calves absorbed IgG from colostrum similarly to control calves delivered vaginally.

Antibodies to synaptosomal membranes of rat hippocampus and caudate nucleus: Immunological and behavioral characteristics

Synaptosomal plasma membranes (SPMs) from the caudate nucleus (Cd) and hippocampus (HPC) were used as immunogens against which antisera were raised in rabbits (anti-HPC and anti-Cd serum, respectively). All immunologic reactivity of anti-Cd serum could be neutralized by absorption of the serum with either HPC-SPMs or Cd-SPMs. Similarly, all reactivity of the anti-HPC serum was neutralized by absorption with HPC-SPMs. On the other hand, a substantial part of the reactivity of anti-HPC serum remained after absorption with Cd-SPMs. These results indicate that the HPC-SPM preparation contains antigenic determinants which are absent from Cd-SPM preparation. When the immunoglobulin type G (IgG) fractions isolated from anti-HPC serum and anti-Cd serum were injected daily for 14 days into neonatal rats, they caused behavioral deficits which were observed in adulthood. No differences in general activity or in open-field behavior were found between those animals and controls. However, rats which had been injected for 14 days with anti-HPC IgG showed impairments in reversal learning in a T maze, in the retention of a passive avoidance task and in the acquisition of active avoidance. Rats injected with anti-Cd IgG showed much smaller impairments.