In-house assays for detecting anti-SARS-CoV-2 antibodies in serum and urine: Correlation with COVID-19 severity from a cohort study in QatarVaikath, Al-Nesf, Majbour
et alJ Infect Public Health (2025) 18 (6), 102744
Abstract: Serological assays targeting antibodies against key viral proteins, including the Spike (S1), Receptor Binding Domain (RBD), and Nucleocapsid, play a critical role in understanding immunity and supporting diagnostic efforts during COVID-19 pandemic, and afterward. This study aimed to develop and validate in-house assays for detecting anti-SARS-CoV-2 antibodies in serum and urine.ELISA-based assay was developed to detect IgG and IgM antibodies against SARS-CoV-2. The assay was examined in serum and urine samples of two different cohort of patients affected by COVID-19 disease with different severity and compared to age and sex matched control group. Neutralizing antibody activity was evaluated using an RBD-ACE2 binding inhibition assay. Additionally, a Sengenics protein microarray platform was employed to assess epitope-specific antibody responses.The in-house ELISA assay reliably detected antibodies in both 163 serum and 64 urine samples compared to 50 serum samples from healthy control, with strong correlations observed between antibody levels in the two biofluids. Neutralizing antibody levels correlated positively with disease severity, highlighting their clinical relevance. The performance of the in-house assays was comparable to commercial kits, and the Sengenics microarray provided detailed insights into antibody profiles, identifying dominant epitopes within the Nucleocapsid core domain and RBD.The developed in-house assay demonstrated robust performance and versatility, offering a cost-effective and scalable alternative to commercial kits. Their ability to detect antibodies in both serum and urine highlighted their potential as non-invasive diagnostic tools. These findings contribute to advancing sero-diagnostic capabilities, improving understanding of immune responses to SARS-CoV-2, and supporting global efforts to monitor and manage COVID-19 effectively.Copyright © 2025. Published by Elsevier Ltd.
P robiotics i nfluencing r esponse of a ntibodies over t ime in s eniors after CO VID-19 v accine (PIRATES-COV): a randomised controlled trial protocolPasquier, Plourde, Ramanathan
et alBMJ Open (2025) 15 (3), e088231
Abstract: The elderly are particularly vulnerable to morbidity and mortality from COVID-19, the disease caused by the SARS-CoV-2. Approximately 20% of the elderly showed no antibodies 3-5 months post-second dose of the COVID-19 vaccine. As probiotics have been shown to increase influenza-specific antibody levels post-influenza vaccination, we aim to reduce the percentage of participants without antibodies against the SARS-CoV-2 spike protein receptor-binding domain (anti-S1-RBD) at 6 months post-vaccination.Our study design is a double-blind randomised controlled trial, using intention-to-treat analysis. Eligible participants are a purposive sample of 688 adults aged 65-89 years, in Quebec, Canada, not diagnosed with COVID-19 in the 3 months prior to recruitment and who wish to receive a government-recommended mRNA booster (Pfizer-BioNTech, Moderna) vaccine. The intervention consists of one capsule/day of a probiotic dietary supplement of Lacticaseibacillus rhamnosus and Lacticaseibacillus casei 6×109 CFU/capsule or a placebo, for 15 days pre-booster and post-booster vaccine. All participants provide dried blood spot samples at three timepoints (inclusion, 3 and 6 months post-vaccination) and a stool sample for microbiome analysis. A subgroup of 100 participants living near Sherbrooke, Quebec, is expected to volunteer for two onsite blood-test visits (at inclusion and 6 months post-vaccination). The primary outcome is the percentage of participants without anti-S1-RBD antibodies at 6 months post-vaccination. Secondary outcomes include longitudinal analysis of anti-S1-RBD and anti-N antibodies at three timepoints. In the subgroup, serum levels of neutralising antibodies will be determined at inclusion and 6 months post-vaccination. Probiotic and vaccine side effects are monitored. At the end of the study, we expect to identify the adjuvant effect of probiotic on vaccine-induced immune response.The study was approved by Research Ethics Board of the Centre Intégré Universitaire de Santé et des Services Sociaux de l'Estrie- Centre Hospitalier Universitaire de Sherbrooke (CIUSSS de l'Estrie-CHUS) and the CHU de Québec-Université Laval # MP-31-2022-4598 as well as Health Canada. All participants will provide informed consent. Results will be disseminated to the scientific community and to all networks related in this research.NCT05195151.© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.
Time course and determinants of the antibody response to SARS-CoV-2 in Costa Rica: the RESPIRA studyHerrero, Fantin, Loría
et alBMC Infect Dis (2025) 25 (1), 376
Abstract: Antibodies to SARS-CoV-2 are essential for protection or reduction in severity of subsequent disease. We studied antibody responses to spike protein receptor-binding domain (S1-RBD) and nucleocapsid (N) in a population-based sample of COVID-19 cases in Costa Rica.As part of the RESPIRA study, we selected an age-stratified random sample of PCR-confirmed COVID-19 cases diagnosed from March 2020 to July 2021. Antibodies were determined with multiplex serology in 794 unvaccinated subjects diagnosed 3 days to 17 months before recruitment to investigate immune response to natural infection. In addition, neutralizing antibodies were determined in 136 randomly selected participants. We estimated antibody positivity and GMTs by time since diagnosis and explored determinants using multivariate regression.Most participants tested 15-29 days after PCR diagnosis were seropositive for N (90%) and S1-RBD antibodies (96%) and had the highest GMTs for both antibodies. Only 42% of subjects tested one year after infection were seropositive for N antibodies, compared to 97% for S1-RBD. GMTs for neutralizing antibodies peaked 15-89 days after infection and declined but remained positive for 95% of subjects thereafter. In multivariate models, antibodies were significantly higher among men and increased with age and severity of the clinical presentation. The correlation of multiplex and neutralizing antibodies was high (0.72 [95% CI = 0.63-0.79]) and stronger among women.A robust immune response against N and S1-RBD is elicited by COVID-19 a few days after infection. While S1-RBD antibodies are present after > 1 year, N antibodies decline significantly. Antibody levels are higher in men and increase with age and severity of disease. The different immune response patterns by sex warrant further investigation.RESPIRA Study ClinicalTrials.gov ID: NCT04537338 (3 September 2020).© 2025. The Author(s).
Electric spiking activity in epithelial cellsYu, Granick
Proc Natl Acad Sci U S A (2025) 122 (12), e2427123122
Abstract: Epithelial cells (human keratinocyte cells and the canine MDCK cell line), traditionally viewed as electrically non-self-excitable and involved primarily in physiological functions such as barrier presentation, absorption, secretion, and protection, are shown here to exhibit traveling extracellular electric charge when they recover from spatially focused, laser-induced wounding of confluent monolayers cultured on a multielectrode array chip. Voltage spikes measured on these electrodes display depolarization, repolarization, and hyperpolarization phases with amplitudes similar to the action potentials of neurons but with the markedly slower duration of 1 to 2 s. Some propagate distances up to hundreds of μm from the wound with a mean speed of around 10 mm s-1. Generation and transmission of bioelectric signals are significantly influenced by the perturbation of mechanosensitive cationic ion channels. These direct measurements confirm bioelectric signaling that previous work has hypothesized to regulate epithelial cell development and may have relevance to the frequency parameter selection of bioelectric devices.
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