Median Titer Research Articles

Natural IgG against S-Protein and RBD of SARS-CoV-2 Do Not Bind and Hydrolyze DNA and Are Not Autoimmune.

Since the onset of the COVID-19 pandemic, numerous publications have appeared describing autoimmune pathologies developing after a coronavirus infection, with several papers reporting autoantibody production during the acute period of the disease. Several viral diseases are known to trigger autoimmune processes, and the appearance of catalytic antibodies with DNase activity is one of the earliest markers of several autoimmune pathologies. Therefore, we analyzed whether IgG antibodies from blood plasma of SARS-CoV-2 patients after recovery could bind and hydrolyze DNA. We analyzed how vaccination of patients with adenovirus Sputnik V vaccine influences the production of abzymes with DNase activity. Four groups were selected for the analysis, each containing 25 patients according to their relative titers of antibodies to S-protein: with high and median titers, vaccinated with Sputnik V with high titers, and a control group of donors with negative titers. The relative titers of antibodies against DNA and the relative DNase activity of IgGs depended very much on the individual patient and the donor, and no significant correlation was found between the relative values of antibodies titers and their DNase activity. Our results indicate that COVID-19 disease and vaccination with adenoviral Sputnik V vaccine do not result in the development or enhancement of strong autoimmune reactions as in the typical autoimmune diseases associated with the production of anti-DNA and DNA hydrolyzing antibodies.

A switchable secrete-and-capture system enables efficient selection of Pichia pastoris clones producing high yields of Fab fragments

Pichia pastoris (syn. Komagataella phaffii) represents a commonly used expression system in the biotech industry. High clonal variation of transformants, however, typically results in a broad range of specific productivities for secreted proteins. To isolate rare clones with exceedingly high product titers, an extensive number of clones need to be screened. In contrast to high-throughput screenings of P. pastoris clones in microtiter plates, secrete-and-capture methodologies have the potential to efficiently isolate high-producer clones among millions of cells through fluorescence-activated cell sorting (FACS).Here, we describe a novel approach for the non-covalent binding of fragment antigen-binding (Fab) proteins to the cell surface for the isolation of high-producing clones. Eight different single-chain variable fragment (scFv)-based capture matrices specific for the constant part of the Fabs were fused to the Saccharomyces cerevisiae alpha-agglutinin (SAG1) anchor protein for surface display in P. pastoris. By encoding the capture matrix on an episomal plasmid harboring inherently unstable autonomously replicating sequences (ARS), this secrete-and-capture system offers a switchable scFv display. Efficient plasmid clearance upon removal of selective pressure enabled the direct use of isolated clones for subsequent Fab production. Flow-sorted clones (n = 276) displaying high amounts of Fabs showed a significant increase in median Fab titers detected in the cell-free supernatant (CFS) compared to unsorted clones (n = 276) when cells were cultivated in microtiter plates (factor in the range of ∼21–49). Fab titers of clones exhibiting the highest product titer observed for each of the two approaches were increased by up to 8-fold for the sorted clone. Improved Fab yields of sorted cells vs. unsorted cells were confirmed in an upscaled shake flask cultivation of selected candidates (factor in the range of ∼2–3). Hence, the developed display-based selection method proved to be a valuable tool for efficient clone screening in the early stages of our bioprocess development.

Association of Human Leucocyte Antigen Polymorphism with Coronavirus Disease 19 in Renal Transplant Recipients.

Human leucocyte antigens (HLAs) are highly polymorphic glycoproteins expressed at the surface of all nucleated cells. It is required for the SARS-CoV-2 peptide antigen presentation to immune cells for their effector response. However, polymorphism in HLA significantly impacts the binding of SARS-CoV-2 antigenic peptide to the HLA pocket and regulates immune activation. In this study, 514 renal transplant recipients (RTRs) were recruited from the outpatient department and categorized either into symptomatic (n = 173) or asymptomatic groups (n = 341) based on Coronavirus disease-19 (COVID-19) symptoms. The anti-SARS-CoV-2 spike protein-specific IgG antibody titer was measured by chemiluminescent microparticle immune-assay methods in 310 RTRs. The HLA details of 514 patients were retrieved from the electronic medical records and analyzed retrospectively. We found that HLA antigen allele A*24 was significantly associated with asymptomatic infection in 22.78%, HLA C*02 in 4.51%, DRB1*12 in 10.85%, and HLA DQA1*02 in 27.74% of RTRs. Whereas HLA A*29 in 3.46%, A*33 in 26.01%, B*13 in 10.40%, DRB1*10 in 4.62%, DRB1*15 in 39.30%, DRB1*30 in 1.15%, and DQA1*60 in 3.57% of RTRs were associated with symptomatic infection. HLA DRB1*13 and DRB1*15 were associated with moderate to severe degrees of COVID-19 disease. The seroconversion rate in asymptomatic patients was 118/137 (86.13%), had a median titer of 647.80 au/ml, compared to symptomatic patients 148/173 (85.54%) with a median titer of 400.00 au/ml, which was not significant between the two groups (P = 0.88 and 0.13). In conclusion, HLA alleles A*24, C*02, DRB1*12, and DQA1*02 were significantly associated with asymptomatic infection, and A*29, A*33, B*13, DRB1*10, DRB*15, and DRB1*30 were significantly associated with symptomatic infection. HLA DRB1*13 and DRB1*15 were associated with moderate to severe degrees of COVID-19 disease.

Measles Virus Neutralizing Antibody Response and Durability Two Years after One or Two Doses of Measles-Mumps-Rubella Vaccine among Young Seronegative Healthcare Workers.

Although there have been several studies regarding the immunogenicity of one or two booster doses of the measles-mumps-rubella (MMR) vaccine in measles-seronegative young adults, limited data are available about how long the immune response is sustained compared with natural infection. This study included seronegative healthcare workers (HCWs) (aged 21-38 years) who received one or two doses of the measles-mumps-rubella (MMR) vaccine and HCWs with laboratory-confirmed measles infection during an outbreak in 2019. We compared neutralizing antibody titers measured using the plaque reduction neutralization (PRN) test and measles-specific immunoglobulin G (IgG) using chemiluminescent immunoassays 2 years after vaccination or infection. Among 107 HCWs with seronegative measles IgGs, the overall seroconversion rate of measles IgGs remained 82.2% (88/107), and 45.8% (49/107) of the participants had a medium (121-900) or high (>900) PRN titer after 2 years from one or two booster doses. The measles-neutralizing antibody titers of both PRN titer (ND50) and geometric mean concentration 2 years after natural infection were significantly higher than those of one or two booster doses of the MMR vaccine (p < 0.001 and p < 0.001, respectively). Our results suggest that serologic screening followed by appropriate postexposure prophylaxis can be beneficial for young HCWs without a history of natural infection especially in a measles outbreak setting, because of possible susceptibility to measles despite booster MMR vaccination 2 years ago. Long-term data about sustainable humoral immunity after one or two booster vaccination are needed based on the exact vaccination history.

The risk factors of SARS-CoV-2 antibody level differences in healthcare workers post vaccination in Siloam hospitals: A nationwide multicenter study

BackgroundSeveral vaccines have been approved against COVID-19, and five have been used in Indonesia. Due to the decrease in antibody levels three to six months after the second dose of CoronaVac, healthcare workers received the third booster of mRNA vaccine (mRNA-1273) to increase the antibody level. This study aimed to evaluate the risk factors of anti-S-RBD IgG levels differences in healthcare workers.MethodsThis study is a retrospective cohort study of 576 healthcare workers without previous SARS-CoV-2 infection who received two doses of CoronaVac and the third dose of mRNA-1273 six months after the second dose. Blood samples were obtained 2nd, 6th, 12th, and 24th weeks after the second dose of CoronaVac vaccine administration, with mRNA-1273 booster on week 20. Quantitative measurements of IgG antibodies were performed with Elecsys Anti-SARS-CoV-2 S immunoassay. We identify the baseline factors predicting post-vaccination antibody titers using univariate and multivariate linear regression analysis.ResultsThis study comprised 576 participants aged 32 years old, 72.05% female, and 45.84% from high-risk occupation subgroups. The median antibodies titer level on the 2nd, 6th, 12th, and 24th weeks after the second vaccine dose administration were 40.99 u/mL, 42.01 u/mL, 54.78 u/mL, and 23,225 u/mL. Antibody levels trended highest in female and younger age group (20-29 years old).ConclusionThe third dose of vaccine increased the quantitative SARS-CoV-2 spike IgG antibody titers and eliminated differences in antibodies titer by gender. Keywords: Antibodies titer, COVID-19, Immune response, S-RBD IgG, Vaccine

A third dose SARS‑CoV‑2 BNT162b2 mRNA vaccine results in improved immune response in hemodialysis patients.

The hemodialysis (HD) population has been a vulnerable group during the coronavirus disease 2019 (COVID-19) pandemic. Advanced chronic kidney disease with uremia is associated with weaker immune response to infections and an attenuated response to vaccines. The aim of this study was to study the humoral and cellular response to the second and third doses of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS‑CoV‑2) BNT162b2 mRNA vaccine in HD patients and to follow the response over time. The patients received their first two vaccine doses from 28 December 2020 within a 4-week interval and the third dose in September 2021 and were followed-up for humoral and cellular immune response at 1) 7-15 weeks and 2) 6-8 months after dose two (no t-cell reactivity measured), and 3) 3 weeks and 4) 3 months after dose three. Fifty patients were initially enrolled, and 40 patients were followed during the entire study. Levels of COVID-19 (SARS-CoV-2) IgG antibody against the Spike antigen (anti-S) and T-cell reactivity testing against the Spike protein using Enzyme-Linked ImmunoSpot (ELISPOT) technology were evaluated. IgG antibodies to anti-S were detected in 35 (88%) of the 40 patients 7-15 weeks after vaccine dose two, 31 (78%) were positive, and 4 (10%) borderline. The median anti-S titer was 606 Abbott Units/milliliter (AU/mL) (interquartile range [IQR] 134-1,712). Three months after the third dose, anti-S was detected in 38 (95%) of 40 patients (P < 0.01 compared to after dose two), and the median anti-S titer was 9,910 AU/mL (IQR 2,325-26,975). Cellular reactivity was detected in 22 (55%), 34 (85%), and 28 (71%) of the 40 patients, and the median T-cell response was 9.5 (IQR 3.5-80), 51.5 (14.8-132), and 19.5 (8.8-54.2) units, respectively, for 6-8 months after dose two, 3 weeks, and 3 months after dose three. Our data show that a third dose of SARS‑CoV‑2 BNT162b2 mRNA vaccine gives a robust and improved immunological response in HD patients, but a few patients did not develop any anti-S response during the entire study, indicating the importance to monitor the vaccine response since those who do not respond could now be given monoclonal antibodies if they contract a COVID-19 infection or in the future antivirals.

Antibody Response to ChAdOx1 nCoV-19 (AZD1222) Vaccine in Kidney Transplant Recipients.

Kidney transplant recipients (KTRs) are at a much higher risk of complications and death following COVID-19 and are poor vaccine responders. The data are limited on the immune response to Covishield® in KTRs. We prospectively recruited a cohort of 67 KTRs aged >18 between April 2021 and December 2021. Each participant was given two intramuscular doses of Covishield®, each of 0.5 mL, at an interval of 12 weeks. A blood specimen of 5.0 mL was collected from each participant at two points within a few days before administering the first dose of the vaccine and at any time between 4–12 weeks after administering the second dose. The sera were tested for anti-RBD antibody (ARAb) titre and neutralising antibody (NAb). An ACE2 competition assay was used as a proxy for virus neutralization. According to the prior COVID-19 infection, participants were grouped as (i) group A: prior symptomatic COVID-19 infection, (ii) group B: prior asymptomatic COVID-19 infection as evidenced by detectable ARAb in the prevaccination specimen, (iii) Group C: no prior infection with COVID-19, (iv) group D: Unclassified, i.e., participants had no symptoms suggestive of COVID-19, but their prevaccination specimen was not available for ARAb testing before vaccination. Fifty of sixty-seven participants (74.6%) provided paired specimens (group A 14, group B 27, and group C 9) and 17 participants (25.4%) provided only postvaccination specimens (group D). In the overall cohort (n = 67), 91% and 77.6% of participants developed ARAb and NAb, respectively. Their ARAb titre and NAb proportion were 2927 (520–7124) U/mL and 87.9 (24.4–93.2) %, respectively. Their median ARAb titre increased 65.6 folds, from 38.2 U/mL to 3137 U/mL. Similarly, the proportion of participants with NAb increased from 56% to 86%, and the NAb proportion raised 2.7 folds, from 23% to 91%. A comparison of vaccine response between the study groups showed that all those with or without prior COVID-19 infection showed a significant rise in ARAb titre (p < 0.05) and NAb proportion (p < 0.05) after the two doses of vaccine administration. The median value of folds rise in anti-RBD and NAb between groups A and B were comparable. Hence, ARAb is present in more than 3/4th of KTRs before the ChAdOx1 vaccine in India. The titer of ARAb and the proportion of NAb significantly increased after the two doses of the ChAdOx1 vaccine in KTRs.

Attenuated humoral response against SARS-CoV-2 mRNA vaccination in allogeneic stem cell transplantation recipients.

Antibody persistence several months after SARS‐CoV‐2 mRNA vaccination in allogeneic stem cell transplantation recipients remains largely unknown. We sequentially evaluated the humoral response to two doses of mRNA vaccines in 128 adult recipients and identified the risk factors involved in a poor response. The median interval between stem cell transplantation and vaccination was 2.7 years. The SARS‐CoV‐2 S1 antibody became positive after the second vaccination dose in 87.6% of the recipients, and the median titer was 1,235.4 arbitrary units (AU)/mL. In patients on corticosteroid treatment, the corticosteroid dose inversely correlated with antibody titer. Multivariate analysis identified risk factors for poor peak response such as an interval from stem cell transplantation ≤ 1 year, history of clinically significant cytomegalovirus infection, and use of > 5 mg/day prednisolone at vaccination. Six months after vaccination, the median titer decreased to 185.15 AU/mL, and use of > 5 mg/day prednisolone at vaccination was significantly associated with a poor response. These results indicate that early vaccination after stem cell transplantation (<12 months) and cytomegalovirus infection are risk factors for poor peak response, while steroid use is important for a peak as well as a persistent response. In conclusion, although humoral response is observed in many stem cell transplantation recipients after two doses of vaccination, antibody titers diminish with time, and factors associated with persistence and a peak immunity should be considered separately.

Transplant outcomes of 100 cases of living-donor ABO-incompatible kidney transplantation.

Although ABO-incompatible (ABOi) kidney transplantation (KT) has been performed successfully, a standard preconditioning regimen has not been established. Based on the initial antidonor ABO antibody titers, an individualized preconditioning regimen is developed, and this study explored the efficacy and safety of the regimen. From September 1, 2014, to September 1, 2020, we performed 1668 consecutive living-donor KTs, including 100 ABOi and 1568 ABO-compatible (ABOc) KTs. ABOi KT recipients (KTRs) with a lower antibody titer (≤1:8) were administered oral immunosuppressive drugs (OIs) before KT, while patients with a medium titer (1:16) received OIs plus antibody-removal therapy (plasma exchange/double-filtration plasmapheresis), patients with a higher titer (≥1:32) were in addition received rituximab (Rit). Competing risk analyses were conducted to estimate the cumulative incidence of infection, acute rejection (AR), graft loss, and patient death. After propensity score analyses, 100 ABOi KTRs and 200 matched ABOc KTRs were selected. There were no significant differences in graft and patient survival between the ABOi and ABOc groups (P = 0.787, P = 0.386, respectively). After using the individualized preconditioning regimen, ABOi KTRs showed a similar cumulative incidence of AR (10.0% υs . 10.5%, P = 0.346). Among the ABOi KTRs, the Rit-free group had a similar cumulative incidence of AR ( P = 0.714) compared to that of the Rit-treated group. Multivariate competing risk analyses revealed that a Rit-free regimen reduced the risk of infection (HR: 0.31; 95% CI: 0.12-0.78, P = 0.013). Notably, antibody titer rebound was more common in ABOi KTRs receiving a Rit-free preconditioning regimen ( P = 0.013) than those receiving Rit. ABOi KTRs with antibody titer rebound had a 2.72-fold risk of AR (HR: 2.72, 95% CI: 1.01-7.31, P = 0.048). ABOi KTRs had similar serum creatinine and estimated glomerular filtration rate compared to those of ABOc KTRs after the first year. An individualized preconditioning regimen can achieve comparable graft and patient survival rates in ABOi KT with ABOc KT. Rit-free preconditioning effectively prevented AR without increasing the risk of infectious events in those with lower initial titers; however, antibody titer rebound should be monitored.

Peripheral neuropathy and MOG-IgG: A clinical and neuropathological retrospective study

BackgroundMyelin oligodendrocyte glycoprotein antibodies (MOG-Abs) may rarely be associated with peripheral nervous system involvement. We aimed to test MOG-Abs in patients with undetermined peripheral neuropathy (PN). MethodsConsecutive patients with available sural nerve biopsy and paired serum sample were retrospectively identified (January, 1st 2016-November, 1st 2021) and tested for MOG-Abs with live cell-based assay (CBA). Patients with antibody titre ≥1:160 (secondary H + L antibody) and selective MOG-IgG presence (IgG-Fc predominance) were considered MOG-IgG positive. All positive samples were analysed with immunohistochemistry and CBAs for antibodies against Neurofascin-155 and Contactin-1. Clinical and neuropathological data were collected through clinical reports. ResultsAmong 163 patients, 5 (3%) resulted positive for predominantly IgG MOG-Abs (median titer 1:320, range 1:160–1:5120), none showed other concomitant antibodies. Median age was 74 years-old (range 55–81), median disease duration was 60 months (range 1–167), 60% of patients were female. Of these, 4/5 cases had clinical features suggestive of acute (n = 1) or chronic (n = 3) inflammatory demyelinating neuropathy, 2/5 fulfilled the criteria of combined central and peripheral demyelination (CCPD) whilst 3/5 had isolated PNS involvement. Neuropathological findings showed mixed axonal-demyelinating features in 2/5, predominant demyelination in 3/5 cases. Other neuropathological hallmarks included paranodal demyelination (n = 3), myelin outfoldings (n = 4), slight inflammatory infiltrates (n = 3), onion bulbs (n = 3), and clusters of regeneration (n = 4). DiscussionMOG-IgG can be detected in patients with isolated PN or CCPD. Clinical and neuropathological features are suggestive for demyelination and slight inflammation. Further studies should include larger cohorts of patients to elucidate the utility of MOG-Abs testing in PN.

Human Leukocyte Antigen Association with Anti-SARS-CoV-2 Spike Protein Antibody Seroconversion in Renal Allograft Recipients - An Observational Study

Cellular and humoral responses are required for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) eradication. Antigen-presenting cells load SARS-CoV-2 peptides on human leukocyte antigen (HLA) with different avidities and present to T- and B-cells for imposing humoral and cellular responses. Due to immunosuppression, renal transplant recipient (RTR) patients are speculated to poorly form the antibody against the SARS-CoV-2. Therefore, determining the association of specific HLA alleles with anti-SARS-CoV-2 spike protein antibody formation will be helpful in managing the RTR having specific HLA alleles from SARS-CoV-2 infection and vaccination. Materials and Methods: In this study, anti-SARS-CoV-2 spike protein antibody in 161 RTRs was determined by the chemiluminescent microparticle immunoassay methods, and HLA alleles were determined by the polymerase chain reaction-single-strand oligonucleotide methods and analyzed to study the HLA allele association with anti-SARS-CoV-2 spike protein-specific humoral response and severity of COVID-19 symptoms in recently SARS-CoV-2-infected RTRs. Results: The anti-SARS-CoV-2 spike protein specific antibody seroconversion rate in RTRs was 90.06% with a median titer of 751.80 AU/ml. The HLA class I alleles, A*11 in 22.1%, A*24 in 21.37%, A*33 in 20.68%, HLA B*15 in 11%, B*07 in 8.27%, HLA-C*30 in 20.93%, C*70 in 23.25% and HLA Class II alleles, DRB1*07 in 18.62%, DRB1*04 in 13.8%, HLA-DRB1*10 in 14.48%, HLA-DQA1*50 in 32.55% of RTRs were associated with the seroconversion. The mean SARS-CoV-2 clearance time was 18.25 ± 8.14 days. Conclusions: RTRs with SARS-CoV-2 infection developed a robust seroconversion rate of 90.0% and different alleles of HLA-B, DRB1, and DQA1 were significantly associated with the seroconversion.

Positive autoantibodies in living liver donors.

BACKGROUNDThere is a nationwide shortage of organs available for liver transplantation. Living donors help meet this growing demand. Not uncommonly, donors will have positive autoantibodies. However, it is unclear whether donor positive autoantibodies are correlated with worse outcomes following living liver donor transplantations. AIMTo analyze the significance of positive autoantibodies in donors on post-transplant outcomes in recipients.METHODSWe performed a retrospective review of living liver donors who had undergone liver transplantation between January 1, 2012 and August 31, 2021. Demographic characteristics and pre-transplant data including antinuclear antibodies (ANA) and anti-smooth muscle antibody titers were collected in donors. Outcomes of interest were post-transplantation complications including mortality, biliary strictures, biliary leaks, infection, and rejection. Pediatric recipients and donors without measured pre-transplant autoantibody serologies were excluded from this study.RESULTS172 living donor liver transplantations were performed during the study period, of which 115 patients met inclusion criteria. 37 (32%) living donors were autoantibody-positive with a median ANA titer of 1:160 (range 1:80 to 1:1280) and median anti-SMA titer of 1:40 (range 1:20 to 1:160). There were no significant differences in baseline demographics between the autoantibody positive and negative donors. Post-transplantation rates of death (P value = 1), infections (P value = 0.66), and overall rates of complications (P value = 0.52) were similar between the autoantibody positive and negative groups. Higher incidences of anastomotic strictures and rejection were observed in the autoantibody positive group; however, these differences were not statistically significant (P value = 0.07 and P value = 0.30 respectively).CONCLUSIONIsolated pre-transplant autoantibody positivity is not correlated to worse post-transplant outcomes in living liver donor transplants.

The clinical value of indirect immunofluorescence for screening anti-rods and rings antibodies: A retrospective study of two centers in China.

ObjectiveTo investigate the distribution and clinical significance of the rods and rings (RR) pattern in various diseases.MethodsA total of 169,891 patients in Peking Union Medical College Hospital (PUMCH) and 29,458 patients in Inner Mongolia People’s Hospital (IMPH) from January 2018 to December 2020 were included, and the results of ANA (antinuclear antibodies) and special antibodies were analyzed retrospectively.ResultsThe positive rates of ANA and RR patterns were 34.84%, 0.16% in PUMCH, and 44.73%, 0.23% in IMPH. Anti-RR antibodies mainly appear in adults (≥ 41 years), mostly of low or medium fluorescence titers. Isolated RR patterns were mostly presented (60.30% and 69.12%, respectively), and the RR pattern mixed with the speckled pattern was most commonly observed among patients having two or more patterns. The RR pattern existed in a variety of diseases including hepatitis C, AIDs, pulmonary diseases, nephropathy diseases, and even healthy people. The highest prevalence of the RR pattern was observed in hepatic diseases, such as hepatic dysfunction (0.79%), hepatic cirrhosis (1.05%), PBC (0.85%), and AIH (0.65%), etc. The positive rate of specific antibodies in RR pattern cases was 31.25%, and anti-Ro52 (27, 20.61%) was the most common target antibody.ConclusionThe RR pattern had a low prevalence in ANAs test samples and varied in different nationalities and regions. Except for hepatitis C, it could be observed in AIDs, pulmonary diseases, nephropathy, other hepatic diseases, and even healthy people, but the positive rate was slightly higher in hepatic diseases. Its mechanism of action and clinical relevance still need clarification.

Assessment of the humoral response to the homologous Gam-COVID-Vac (Sputnik V) or heterologous Sputnik V/mRNA-1273 (Moderna) vaccination against SARS-CoV-2 in dialysis patients.

Background and AimDialysis patients are a high-risk population and have a reduced immune response to vaccination against SARS-CoV-2. The aim of this study was to assess the humoral response to homologous Gam-COVID-Vac (Sputnik V) and heterologous Sputnik V/mRNA-1273 (Moderna) vaccination in dialysis patients. The vaccination scheme depended on dose availability and the prioritization of risk populations as established by the Argentine Ministry of Health.Methods Previous COVID-19 infection was determined in symptomatic patients. Binding IgG antibodies against the spike (S) receptor-binding domain (RBD) of SARS-CoV-2 (anti-S-RBD) concentration was assessed between 3 and 16 weeks after the boost dose. Anti-S-RBD antibodies were quantified using the Abbott Diagnostics SARS-CoV-2 IgG II Quant chemiluminescent microparticle immunoassay (CMIA) on an Architect i2000 SR and an Alinity I analyzer (Abbott Diagnostics, Abbott Park, Illinois, USA). To standardize the results to WHO binding antibody units (BAU), a correction factor for Abbott arbitrary units (AU) was applied where 1 BAU/mL equals 0.142 AU, as previously established by Abbott with the WHO international standard NIBSC 20–136. Following the manufacturer’s recommendations, samples were considered reactive for anti-S-RBD when titers were above 50 AU/mL (7.2 BAU/mL). An 80% protective effect (PROT-80) against symptomatic SARS-CoV-2 infection was assumed when anti-S-RBD titers were 506 BAU/ml or higher. Charlson Comorbidity Index (CCI) score was classified as mild = 1–2, moderate = 3–4, and severe ≥ 5. Side effects were evaluated until day 7 by patients´ self-reported questionnaire.ResultsOne hundred seven participants were enrolled [n = 84 homologous (SpV/SpV), nn 23 heterologous (SpV/Mod)]. Median (IQR) age was 64 (50–75) years old and 79 (73.8%) were male. Additionally, 19 (22.6%) of the SpV/SpV and 4 (17.4%) of the SpV/Mod group had a prior confirmed SARS-CoV-2 infection (p = 0.589). In the overall population, 103 patients reached seroconversion (96.3%). Anti-S-RBD IgG median titers (IQR) were higher in the heterologous [1222 (288–5680) BAU/mL] than in the homologous scheme [447 (100–1551) BAU/mL], p = 0.022. In a linear model adjusted for age, gender, days from first vaccination to boost dose and days from the boost dose to the anti-S-RBD IgG determination, previous SARS-COV-2 infection (B: 2062.2; CI95: 1231.8–2892.6; p < 0.001), and SpV/Mod vaccination scheme (B: 1294.6; CI95: 435.58–2147.6; p = 0.003) were independently associated with anti-S-RBD levels. Finally, a higher frequency of adverse effects was associated with the heterologous scheme, although they were well tolerated by all individuals.ConclusionsThe present study provides evidence that the homologous SpV/SpV and heterologous SpV/Mod schemes showed good efficacy and safety in patients on chronic dialysis. These results could be useful for designing future vaccination strategies, especially aimed at this risk group.Graphical abstract

A study on seroconversion following first & second doses of ChAdOx1 nCoV-19 vaccine in Central Kerala.

Vaccination against COVID-19 induces spike protein-binding IgG antibodies, a robust correlate of protection against COVID-19. This study was undertaken to assess the humoral response after completion of both the doses of ChAdOx1 nCoV vaccine in healthcare workers (HCWs) at a tertiary care health centre in India. A cross-sectional COVID-19 vaccine-induced antibody study was conducted among HCWs. IgG antibodies against spike protein were measured at least 28 days after the first dose and the second dose of vaccination in both SARS CoV-2 naïve and recovered HCWs. Mean and median antibody titre following each dose of vaccine and its association with age, gender, co-morbidities and factors such as exercise, stress and sleep deprivation were also explored. Among the 200 vaccine recipients, 91.5 per cent showed seroconversion after the first dose and 99.5 per cent after the second dose. The mean titre after the second dose was significantly higher when compared to the first dose (12.68±4.17 vs. 9.83±6.3, P=0.001). More than half (54%) had high antibody titre ≥12 S/Co (Signal/cut-off). Previous COVID-19 infection was the single most important factor influencing antibody production, where the mean titre just after a single dose [mean-17.81±5.94, median-20.5 (interquartile range [IQR]-3.7)] surpassed the titre after the second dose in SARS CoV-2 naïve individuals [mean-12.29±4.00, median-12.8 (IQR-3.7), P=0.001]. Furthermore, 28 per cent of vaccinees showed a reduction in titre after the second dose. The mean fall in titre was 2.25±1.40 and was more pronounced in males, the younger age group and those with previous COVID-19 infection. ChAdOx1 nCov-19 vaccine after two doses elicited an excellent immune response. However, greater immunogenicity after the first dose was seen among those with previous COVID-19 infection, even surpassing the titre achieved by the second dose of vaccine in SARS CoV-2 naïve recipients. A fall in antibody titre after the second dose is a matter of concern and requires further studies.

Heterologous vaccination of BNT162b2 in Ad26. COV2.S-vaccinated healthcare workers elicits long-term humoral immune response

Background. To date, there are no immunological data for the SARS-CoV-2 heterologous vaccination schedule in the South African (SA) population. Objectives. To assess and compare the immunogenicity and reactogenicity of the Jansen Ad26.COV2.S vaccine with the Pfizer/BioNTechBNT162b2 booster following prime Ad26.COV2.S in 65 SA healthcare workers. Methods. In a prospective, quantitative, cross-sectional trial on individuals &gt;18 years of age vaccinated with a single Ad26.COV2.S dose or single Ad26.COV2.S and a BNT162b2 single-dose/both doses booster, participants filled in a questionnaire on their demographics, type of vaccination, breakthrough infection/s (BTI/s), vaccine reactogenicity, prior SARS-CoV-2 infection and dates of vaccination. Qualitative analysis for presence/absence of anti-S (spike) immunoglobulin G (IgG) was performed using the Euroimmun anti-IgG enzyme-linked immunoassay kit, and anti-S IgG titres were quantitatively assessed using the Abbott IgG Quant II kit. Results. Between 28 October 2021 and 30 November 2021, 65 individuals were enrolled and assigned as either prime Ad26.COV2.S (n=18) or Ad26.COV2.S with a BNT162b2 supplement (n=47) at Charlotte Maxeke Johannesburg Academic Hospital, SA (mean age 45 years (95% confidence interval (CI) 29.5 - 58), 42 women (64.6%) and 23 men (35.4%)). The median IgG titre for the primed Ad26.COV2.S group was 4 272.55 (95% CI 68.40 - 10 351.40) and that for the BNT162b2 supplement group was 7 360.80 (95% CI 4 207.40 - 15 372.60). In the univariate model, the BNT162b2 supplement group showed a significant 1.99 times higher antibody titre factor (95% CI 0.045 - 5.553; p&lt;0.005) than the Ad26.COV2.S group. In both univariate and multivariate models, age, time since prime vaccination, BTI and prior infection failed to show any statistically significant association (p&gt;0.05) with antibody titres in both groups. However, sex (–55.381 (95% CI –76.984 - –13.498; p=0.018) in a multivariate model was found to have a statistically significant association with anti-S IgG titres observed in both groups. Participants who received their first dose of BNT162b2 9 - 10 months after their prime Ad26.COV2.S (n=44) had a higher degree of antibody response than those who received it earlier. Reactogenicity was observed to be manageable, with mild/moderate adverse effects in the study population. Conclusion. A BNT162b2 supplement given in single or two doses as booster in individuals primed with Ad26.COV2.S induced immunological response, with acceptable and manageable reactogenicity. This study provides novel evidence of the highest degree of antibody response in individuals who received a BNT162b2 first dose 9 - 10 months after prime Ad26.COV2.S, implying that a longer time gap between the two vaccines stimulates higher antibody response than a shorter gap, and that this antibody response can persist for as long as 6 months after the last BNT162b2 dose.

Evaluating the Progression to Hypothyroidism in Preconception Euthyroid Thyroid Peroxidase Antibody-Positive Women.

Thyroid peroxidase antibody (TPOAb) positivity is prevalent in women of reproductive age and predisposes to thyroid dysfunction, particularly hypothyroidism, which has adverse effects on pregnancy. This study aimed to report the rate of development of abnormal thyroid function among initially euthyroid TPOAb-positive women recruited into the TABLET trial, to identify factors associated with the development of hypothyroidism, and to compare outcomes between euthyroid and treated hypothyroid individuals. This observational cohort study, conducted at 49 UK hospitals between 2011 and 2016, included euthyroid TPOAb-positive women 16 to 40 years of age with a history of miscarriage or subfertility, planning pregnancy, randomized to levothyroxine 50 mcg daily or placebo. Abnormal thyroid function, conception rate, and live birth rate (LBR) ≥34 weeks were analyzed. Among the women, 70/940 (7.4%) developed subclinical (SCH) or overt (OH) hypothyroidism: 27/470 taking levothyroxine and 43/470 placebo (relative risk [RR] 0.63; 95% CI, 0.39-1.00; P = 0.05); 83% of cases emerged prepregnancy. Baseline median serum TSH concentrations and TPOAb titers were significantly higher in those who developed hypothyroidism vs those who did not (P < 0.001). Treated SCH/OH demonstrated a higher failure-to-conceive rate compared with euthyroid women (adjusted RR 2.02 [1.56-2.62]; P < 0.001). The LBR ≥ 34 weeks was similar in the treated SCH/OH and euthyroid groups (adjusted RR 1.09 [0.77-1.55]; P = 0.6). Approximately 7% of euthyroid TPOAb-positive women will develop hypothyroidism within 1 year preconception or in pregnancy. Conception rates are lower in women with treated SCH/OH compared with euthyroid women, but LBR are comparable. Thyroid function in TPOAb-positive women should be monitored regularly, when trying to conceive, to ensure prompt diagnosis and appropriate treatment initiation.

Correlation between anti-S IgG and neutralizing antibody titers against three live SARS-CoV-2 variants in BNT162b2 vaccine recipients

ABSTRACT We analyzed serially collected serum samples from healthy adults who underwent BNT162b2 vaccination to elucidate the association between spike (S)-IgG antibody titers determined by ELISA using the WHO international standard (NIBSC code 20/136) and neutralizing antibody titers against three live SARS-CoV-2 variants. This study included 53 health care workers who received two doses of the BNT162b2 vaccine. S-IgG and nucleocapsid (N)-IgG antibody titers were measured by ELISA. Neutralizing (NT) antibody responses against three variants (Wuhan D614 G: KUH003, Alpha, and Delta) were evaluated before and after the first and second vaccination. N-IgG were not detected in any serum samples. S-IgG antibody titers remarkably increased after two BNT162b2 vaccine doses in all participants. S-IgG antibody titers were strongly correlated with NT titers against three variants of live viruses: KUH003 (r = 0.86), Alpha (r = 0.72), and Delta (r = 0.84). Serum samples from participants after one dose of BNT162b2 neutralized Alpha efficiently (median titer, 113.0), but median NT titers against KUH003 and Delta variants were lower, 57.0 and 28.0, respectively (p < .01). Two doses of the BNT162b2 vaccine elicited a strong immune response in this study. The second dose was required for induction of a strong booster effect. Serum collected from BNT162b2 vaccine recipients contained significantly lower neutralizing activity against Delta than that of against KUH003 (p < .0001) and Alpha (p < .0001). If a new variant emerges, live virus-based NT titers should be examined in serum obtained from vaccine recipients to evaluate vaccine efficacy for protection against infection.

Withholding methotrexate after vaccination with ChAdOx1 nCov19 in patients with rheumatoid or psoriatic arthritis in India (MIVAC I and II): results of two, parallel, assessor-masked, randomised controlled trials.

BackgroundThere is a necessity for an optimal COVID-19 vaccination strategy for vulnerable population groups, including people with autoimmune inflammatory arthritis on immunosuppressants such as methotrexate, which inhibit vaccine-induced immunity against SARS-CoV-2. Thus, we aimed to assess the effects of withholding methotrexate for 2 weeks after each dose of ChAdOx1 nCov-19 (Oxford–AstraZeneca) vaccine (MIVAC I) or only after the second dose of vaccine (MIVAC II) compared with continuation of methotrexate, in terms of post-vaccination antibody titres and disease flare rates.MethodsMIVAC I and II were two parallel, independent, assessor-masked, randomised trials. The trials were done at a single centre (Dr Shenoy's Centre for Arthritis and Rheumatism Excellence; Kochi, India) in people with either rheumatoid arthritis or psoriatic arthritis with stable disease activity, who had been on a fixed dose of methotrexate for the preceding 6 weeks. Those with previous COVID-19 or who were positive for anti-SARS-CoV-2 nucleocapsid antibodies were excluded from the trials. People on high-dose corticosteroids and rituximab were also excluded, whereas other disease-modifying antirheumatic drugs were allowed. In MIVAC I, participants were randomly assigned (1:1) to stop methotrexate treatment for 2 weeks after each vaccine dose or to continue methotrexate treatment. In MIVAC II, participants who had continued methotrexate during the first dose of vaccine were randomly assigned (1:1) to withhold methotrexate for 2 weeks after the second dose of vaccine or to continue to take methotrexate. The treating physician was masked to the group assignments. The primary outcome for both MIVAC I and MIVAC II was the titre (absolute value) of anti-receptor binding domain (RBD) antibody measured 4 weeks after the second dose of vaccine. All analyses were done per protocol. The trials were registered with the Clinical Trials Registry- India, number CTRI/2021/07/034639 (MIVAC I) and CTRI/2021/07/035307 (MIVAC II).FindingsBetween July 6 and Dec 15, 2021, participants were recruited to the trials. In MIVAC I, 250 participants were randomly assigned and 158 completed the study as per the protocol (80 in the methotrexate hold group and 78 in the control group; 148 [94%] were women and 10 [6%] were men). The median post-vaccination antibody titres in the methotrexate hold group were significantly higher compared with the control group (2484·0 IU/mL, IQR 1050·0–4388·8 vs 1147·5 IU/mL, 433·5–2360·3; p=0·0014). In MIVAC II, 178 participants were randomly assigned and 157 completed the study per protocol (76 in the methotrexate hold group and 81 in the control group; 135 [86%] were women and 22 [14%] were men). The methotrexate hold group had higher post-vaccination antibody titres compared with the control group (2553·5 IU/ml, IQR 1792·5–4823·8 vs 990·5, 356·1–2252·5; p<0·0001). There were no reports of any serious adverse events during the trial period.InterpretationWithholding methotrexate after both ChAdOx1 nCov-19 vaccine doses and after only the second dose led to higher anti-RBD antibody titres compared with continuation of methotrexate. However, withholding methotrexate only after the second vaccine dose resulted in a similar humoral response to holding methotrexate after both vaccine doses, without an increased risk of arthritis flares. Hence, interruption of methotrexate during the second dose of ChAdOx1 nCov-19 vaccine appears to be a safe and effective strategy to improve the antibody response in patients with rheumatoid or psoriatic arthritis.FundingIndian Rheumatology Association.

Comparison of immunogenicity and clinical effectiveness between BNT162b2 and ChAdOx1 SARS-CoV-2 vaccines in people with end-stage kidney disease receiving haemodialysis: A prospective, observational cohort study.

BackgroundPeople with end-stage kidney disease, including people on haemodialysis, are susceptible to greater COVID-19 related morbidity and mortality. This study compares the immunogenicity and clinical effectiveness of BNT162B2 versus ChAdOx1 in haemodialysis patients.MethodsIn this observational cohort study, 1021 patients were followed-up from time of vaccination until December 2021. All patients underwent weekly RT-PCR screening. Patients were assessed for nucleocapsid(anti-NP) and spike(anti-S) antibodies at timepoints after second(V2) and third(V3) vaccinations. 191 patients were investigated for T-cell responses. Vaccine effectiveness (VE) for prevention of infection, hospitalisation and mortality was evaluated using the formula VE=(1-adjustedHR)x100.Findings45.7% (467/1021) had evidence of prior infection. There was no difference in the proportion of infection-naïve patients who seroconverted by vaccine type, but median anti-S antibody titres were higher post-BNT162b2 compared with ChAdOx1; 462(152-1171) and 78(20-213) BAU/ml respectively, p<0.001. Concomitant immunosuppressant use was a risk factor for non-response, OR 0.12[95% CI 0.05–0.25] p<0.001. Post-V3 (all BNT162b2), median anti-S antibody titres remained higher in those receiving BNT162b2 versus ChAdOx1 as primary doses; 2756(187–1246) and 1250(439–2635) BAU/ml respectively, p=0.003.Anti-S antibodies waned over time. Hierarchical levels of anti-S post-V2 predicted risk of infection; patients with no/low anti-S being at highest risk. VE for preventing infection, hospitalisation and death was 53% (95% CI 6–75), 77% (95% CI 30–92) and 93% (95% CI 59–99) respectively, with no difference seen by vaccine type.InterpretationSerum anti-S concentrations predict risk of breakthrough infection. Anti-S responses vary dependent upon clinical features, infection history and vaccine type. Monitoring of serological responses may enable individualised approaches to vaccine boosters in at risk populations.FundingNational Institute for Health Research (NIHR) Biomedical Research Centre based at Imperial College Healthcare NHS Trust and Imperial College London.