A simple procedure for preparing biotinylated immunoglobulin M from hybridoma culture medium.

We previously reported a chromatography system for purifying immunoglobulin M (IgM) using N,N,N',N'-ethylenediaminetetrakis(methylenephosphonic acid)-modified zirconia particles that selectively absorb immunoglobulins. Here, we report a simple procedure for preparing biotinylated IgM from hybridoma culture medium using this zirconia-based chromatography system. The culture medium of an IgM-producing hybridoma cell line was used as the starting sample solution, and the IgM in the medium was concentrated and partially purified by zirconia chromatography. Next, 9-(biotinamido)-4,7-dioxanonanoic acid N-succinimidyl ester was added to react with the proteins in the sample. Subsequently, only the biotinylated IgM was isolated by Capto Core 400 polishing column chromatography. The entire process was easy to perform, could be completed within 2 h, and provided highly pure biotin-labeled IgM. This procedure is expected to be applicable to the labeling of IgM with various compounds and drugs.

Comparable and sustained levels of S1-RBD-IgG and S1-RBD-IgA in BNT162b2 homologous and CoronaVac-BNT162b2 heterologous booster vaccination: A 22-month prospective study in Malaysia.

This prospective cohort study examines the long-term humoral immune responses post-COVID-19 vaccination in 146 individuals who received either a homologous three-dose BNT162b2 vaccine regimen (PPP) or two primary doses of CoronaVac followed by BNT162b2 booster (SSP) in Malaysia. The study focuses on serum anti-S1-RBD-IgG, -IgA, and -IgM, using the ELISA method. The results show that BNT162b2 outperformed CoronaVac in the two dose primary vaccination series. BNT162b2 booster dose significantly raised serum anti-S1-RBD-IgG and -IgA levels, sustaining this increase from 26 to 52 weeks after administration, regardless of the vaccine regimen. This leads to equivalent levels of anti-S1-RBD-IgG and -IgA after boosting with BNT162b2 in both groups. Breakthrough infections, particularly with the emergence of the Omicron variant, did not result in increased anti-S1-RBD-IgG and -IgA levels. No significant induction of anti-S1-RBD-IgM was observed following multiple vaccine doses. The long-term investigation revealed that PPP and SSP groups had comparable humoral immune responses to SARS-CoV-2, highlighting the advantage of mRNA booster dose in our cohort.

Intracapillary monoclonal IgM deposits disease with massive pseudothrombi: A clinicopathologic study of 4 cases and literature review.

OBJECTIVES: Intracapillary monoclonal IgM deposits disease (ICMDD) has long been considered a hallmark of Waldenström macroglobulinemia (WM) nephropathy. Intracapillary immunoglobulin thrombi are the characteristic features of cryoglobulinemic glomerulonephritis. Here, we reported 4 cases of ICMDD with massive pseudothrombi but without WM or cryoglobulinemia. METHODS: We retrospectively analyzed the clinical and pathologic features of patients diagnosed with ICMDD with massive pseudothrombi. RESULTS: A total of 4 patients (2 men and 2 women) aged 62 to 73 years were enrolled in this study. Microscopic hematuria, edema, and renal insufficiency were present in all patients, along with low serum C3 and C4 in 2 patients. Hematologic examination showed abnormal serum free light chain ratios in all patients and high levels of serum IgM in 3 patients. IgM-κ monoclonal band was identified by serum immunofixation electrophoresis in 3 patients. One patient was diagnosed with small B-cell lymphoma by bone marrow aspiration. Renal biopsy specimen showed massive periodic acid-Schiff-positive hyaline thrombi in the glomerular capillary lumens and also less mesangial, subendothelial, and subepithelial deposits on light microscopy. Immunofluorescence indicated positive staining for IgM (++) and κ light chain staining in the glomerular capillary lumens, capillary walls, and mesangium in all patients. By electron microscopy, the glomerular capillary lumens were filled with homogeneous high-electron-dense deposits without substructure. Two patients were treated with prednisone combined with cyclophosphamide, and 2 received plasma cell-targeted chemotherapy. One patient achieved partial renal remission. CONCLUSIONS: Intracapillary monoclonal IgM deposits disease is a rare disease and not always related to WM. Most patients have IgM monoclonal immunoglobulinemia; renal biopsy specimens mainly show a large number of pseudothrombi in the glomerular capillary lumens. Cyclophosphamide is effective in some patients.

Diagnostic accuracy of hepatitis E virus antibody tests: A comprehensive meta-analysis.

AIM: Hepatitis E virus (HEV) is a major global health issue, with an estimated 20 million infections annually. Although polymerase chain reaction (PCR) is the diagnostic gold standard due to its precision, it is expensive and technically demanding. Antibody tests offer a more practical and cost-effective alternative, although their accuracy can vary due to factors, such as test manufacturer, antigen composition, HEV genotype, and host immune status. METHODS: A comprehensive search was conducted in PubMed, Cochrane, Scopus, and Web of Science databases. Studies included comparing the sensitivity and specificity of immunoglobulin M or immunoglobulin G antibody tests to PCR. Exclusion criteria were non-PCR comparisons, sample sizes under 10, IgA or antigen tests, non-human samples, or missing sensitivity and specificity data. Only English-language full-texts or abstracts were considered. Data analysis was performed using Meta-DTA v2.1.1 and Stata 16.0. RESULTS: The meta-analysis evaluated 8054 blood samples from 21 studies. Immunoglobulin M antibody tests demonstrated an overall sensitivity of 83% (95% CI 76-88) and specificity of 98% (95% CI 97-99). Immunoglobulin G tests showed a sensitivity of 74% (95% CI 62-82) and specificity of 89% (95% CI 84-93). Among manufacturers, Wantai was the most accurate for immunoglobulin M detection, whereas MP led for immunoglobulin G. Notably, test sensitivity improved when the test protein genotype aligned with the HEV genotype. CONCLUSION: This meta-analysis confirmed that antibody assays have a good sensitivity and high specificity to detect HEV infection in situations where PCR is not feasible, highlighting their potential as a practical diagnostic tool.

Anti-SARS-CoV-2 IgM Antibody Levels Measured by an In-House ELISA in a Convalescent Latin Population Persist over Time and Exhibit Neutralizing Capacity to Several Variants of Concern.

BACKGROUND: The coronavirus, SARS-CoV-2, is the causative agent for COVID-19, first registered in Wuhan, China and responsible for more than 6 million deaths worldwide. Currently, RT-PCR is the gold-standard method for diagnosing COVID-19. However, serological tests are needed for screening acute disease diagnosis and screening large populations during the COVID-19 outbreak. OBJECTIVES: Herein, we described the development and validation of an in-house enzyme-linked immunosorbent assay (ELISA) for detecting the levels of anti-spike-1-RBD IgM antibody (CovIgM-ELISA) in well-defined serum/plasma panel for screening and identifying subjects infected with SARS-CoV-2 in a Latin population. METHOD: In-house CovIgM-ELISA has the format of an indirect ELISA. It was optimized by checkerboard titration using recombinant SARS-CoV-2 spike-S1-RBD protein as an antigen. RESULTS: We found that, compared to the RT-PCR as the standard method, the in-house CovIgM-ELISA displayed sensitivities of 96.15% and 93.22% for samples collected up to 30 or 60 days after infection, respectively, as well as 95.59% specificity with 97.3% accuracy. The agreement kappa value (κ) of our CovIgM-ELISA was substantial when compared to RT-PCR (κ = 0.873) and the anti-SARS-CoV-2 IgM ELISA (InBios Int) (κ = 0.684). The IgM levels detected in the population positively correlated with the neutralizing activity against the wild-type, Alpha and Delta variants of concern, but failed to neutralize Omicron. CONCLUSIONS: These data indicate that our in-house CovIgM-ELISA is a compatible performing assay for the detection of SARS-CoV-2 infection.

Immunoglobulin M-based local production in skin-associated lymphoid tissue of flounder (Paralichthys olivaceus) initiated by immersion with inactivated Edwardsiella tarda.

Fish skin, the mucosal site most exposed to external antigens, requires protection by an efficient local mucosal immune system. The mucosal reserve of IgM is recognized as an immune strategy that blocks pathogen invasion to maintain homeostasis, whereas the mechanism of skin-associated local IgM production induced by mucosal antigens is not well know. In this study, we found that the skin of flounder (Paralichthys olivaceus) was equipped with the immune cellular and molecular basis for processing mucosal antigens and triggering local specific responses, i.e., CD4+ Zap-70+ T cells, CD4- Zap-70+ T/NK cells, IgM+ MHCII+ B cells, PNA+ MHCII+ antigen-presenting cells, UEA-1+ WGA+ and UEA-1+ WGA- antigen-sampling cells, as well as secreted IgM and pIgR, as demonstrated by indirect immunofluorescence assay using different antibodies and lectins. After immersion immunization with inactivated Edwardsiella tarda, qPCR assay displayed up-regulation of immune-related genes in flounder skin. Flow cytometry analysis and EdU labeling demonstrated that the mucosal inactivated vaccine induced local proliferation and increased amounts of cutaneous IgM+ B cells. Skin explant culture proved the local production of specific IgM in the skin, which could bind to the surface of E. tarda. ELISA, laser scanning confocal microscopy, and Western blot revealed that, in addition to the elevated IgM levels, pIgR protein level was significantly up-regulated in skin tissue and surface mucus containing the pIgR (secretory component, SC)-tetrameric IgM complex, indicating that mucosal vaccine stimulated up-regulation of IgM and pIgR, which were secreted as a complex into skin mucus to exert the protective effects as secretory IgM. These findings deepen the understanding of IgM-based local responses in the mucosal immunity of teleosts, which will be critical for subsequent investigation into the protective mechanism of mucosal vaccines for fish health.

Seroprevalent study of cytomegalovirus infection in the regions of Jharkhand.

Background: The Human Cytomegalovirus (HCMV) is a type of beta herpesvirus widespread in all human populations. It is estimated that up to 80-100% of adults worldwide and most infections are harmless and can cause severe health complications in infants, like hearing loss and developmental issues. Still, immunocompromised individuals can experience serious complications from the virus. Unfortunately, there is limited information on the prevalence of this virus in our country, and no studies have been reported on the rate of CMV transmission yet. Objectives: This study aims to evaluate the levels of IgM antibodies against Cytomegalovirus (CMV) in East Singhbhum, West Singhbhum, and Seraikela Kharsawan using an ELISA test. Methods: An indirect ELISA test was performed to detect anti-CMV IgM and the period of study was from January'2021 to June'2023. Results: The examination tested 55 people for the TORCH profile of CMV parameters from regions of East Singhbhum, West Singhbhum, and Seraikela Kharsawan. Here, 17 people (30.09%) were IgM positive by ELISA. Conclusions: The serological data confirms that CMV is not being monitored and recognized in the general population, which limits our study between CMV infection, disease, and clinically diagnosed outcomes. This understanding is crucial for the healthcare and policy sectors. Thus, we recommend implementing a surveillance and mindfulness program for at least one-fourth of the population in Jharkhand and continuing to explore and develop effective vaccines to control CMV infections.

Factors Associated with IgG/IgM Levels after SARS-CoV-2 Vaccination in Patients with Head and Neck Cancer.

This study evaluated the factors influencing IgG/IgM antibody levels in 120 patients with head and neck cancer (HNC) following vaccination with inactivated SARS-CoV-2 vaccines. Each patient's demographic and clinical data were documented, and serum IgG and IgM antibodies were detected using a commercial magnetic chemiluminescence enzyme immunoassay kit. The results indicated that while all patients had received at least one vaccine dose, 95 tested positive for IgG and 25 were negative. A higher proportion of IgG-positive patients had received three vaccine doses. Comparatively, gamma-glutamyl transferase levels were elevated in IgM-negative patients. The study further differentiated patients based on their treatment status: 46 were treatment-naive and 74 had received chemotherapy combined with immune checkpoint inhibitors (ICT) at enrollment. Despite similar baseline characteristics and time from vaccination to antibody detection, IgM positivity was significantly lower in the ICT group, with no significant difference in IgG positivity between the treatment-naive and ICT groups. A multivariable analysis identified the number of vaccine doses as an independent factor of IgG positivity, while ICT emerged as an independent risk factor for IgM positivity. Additionally, IgG titers generally declined over time, although patients with higher baseline IgG levels maintained higher titers longer. In conclusion, ICT in patients with HNC does not significantly affect IgG levels post-vaccination. However, booster vaccinations have been shown to be associated with higher IgG positivity, although these levels gradually decrease over time.

Outbreak of Chikungunya Fever in the Central Valley of Chiapas, Mexico.

Chikungunya virus (CHIKV) was isolated from humans in an outbreak of a febrile illness during July and August 2015 in the central valleys of Chiapas, Mexico. Sera obtained from 80 patients were tested for CHIKV RNA by reverse transcriptase polymerase chain reaction (RT-PCR) and for IgM and IgG antibodies by an enzyme linked immunoassay and a commercial indirect immunofluorescence test for CHIKV and dengue virus (DENV). Of the 80 patients, 67 were positive, including 50 for RNA and 17 for IgM. In addition, one patient was coinfected with CHIKV-DENV and 40 patients were positive for IgG antibody to DENV. The clinical manifestations included a high fever, polyarthralgia, headache, myalgia, rash, digestive disorders, conjunctivitis, and adenopathy associated with cervical and axillary inguinal regions. Complete nucleotide sequences of two of the CHIKV isolates showed that they belonged to the Asian lineage but did not group with other Mexican CHIKV isolates from the Chiapas coast. Our findings documented that different Asian lineage strains of CHIKV were circulating simultaneously during the 2015 outbreak in the Central Valley of Chiapas, Mexico. The 2024 cases suggest an explosive scenario of re-emergence of thousands of new Chikungunya and dengue fever (DENF) cases associated with deaths, and a dangerous increase of the four DENV serotypes throughout the Americas, especially in South American countries that have shown a high influx of human migration to southern Mexico. In Mexico, the state of Chiapas and other southern regions are the most vulnerable.

Corrigendum: Risk of SARS-CoV-2 infection among people living with HIV in Wuhan, China.

[This corrects the article DOI: 10.3389/fpubh.2022.833783.].

Cell-mediated and humoral immune responses of cyprinids induced by a live attenuated vaccine against cyprinid herpesvirus 2 infection in comparison to the virus non-permissive high temperature water treatment.

The live attenuated vaccine (P7-P8 strain) against cyprinid herpesvirus 2 (CyHV-2) infection of goldfish shows high protective efficacy. However, the underlying immune mechanism induced by P7-P8 vaccination remains unknown. It is known that the fish survived in the primary infection with CyHV-2 by the virus non-permissive high temperature (HT) water treatment elicit immunity against secondary virus challenge. In this study, the immunity induced by the P7-P8 vaccine was compared with that by HT treatment. To further explore the immunological responses of cyprinids, in addition to goldfish Carassius auratus, susceptible isogenic ginbuna C. auratus langsdorfii was included in this study. In the primary immune response, cyprinids were vaccinated with P7-P8, or treated with HT. In the secondary immune response, cyprinids were challenged with the virulent CyHV-2. The percentage dynamics of CD4-1 and CD8α positive lymphocytes were determined during the primary and secondary immune responses of the two cyprinids. Blood plasma was sampled to assess the anti-CyHV-2 IgM antibody titers. The vaccination with P7-P8 and HT-treatment induced high protection immunity in the cyprinids with relative percentage survival of over 88 % against virulent virus challenge. Our finding shows that the CD8α positive lymphocytes rather than CD4-1 positive lymphocytes play an important role in the secondary immune responses of cyprinids vaccinated with P7-P8. The CD4-1 positive lymphocytes rather than CD8α positive lymphocytes play an important role in the secondary immune responses of cyprinids treated with HT. The antibody titer of vaccinated cyprinids did not increase greatly even after virulent virus challenge. The results suggest the vaccine activates the CD8α cells and the secondary cell-mediated immunity. The differences in the induced immunity mechanisms in fish by the two measures might be based on the virus either being an avirulent virus form that cannot evade host responses or a virulent virus form that cannot propagate at non-permissive temperature.

A novel multiplex and glycoprotein-based immunochromatographic serologic IgM test for the rapid diagnosis of Escherichia coli O157 and O145 causing bloody diarrhea and hemolytic uremic syndrome.

Shiga toxin-producing Escherichia coli (STEC) are the main etiological agents of hemolytic uremic syndrome (HUS). Good clinical management of STEC infections and HUS depends on early, rapid, and accurate diagnosis. Here, we have developed and evaluated the first multiplex and glycoprotein-based immunochromatographic test for the detection of IgM antibodies against the O-polysaccharide of the lipopolysaccharide of E. coli O157 and O145 in human serum samples. A retrospective study was carried out resulting in a diagnostic sensitivity of the E. coli O157/O145 LFIA (lateral flow immunoassay) of 97.1% and 98.9% for O157 and O145, respectively, and 97.9% for both serogroups. The diagnostic specificity was 98.7% for O157 and O145, and the overall specificity 97.4%. In samples obtained before 3 days after the onset of diarrhea, the detection percentage was 83%, increasing to 100% from 3 days onward. Finally, the association of bloody diarrhea (BD) or HUS cases to an STEC infection increased from 22.8% to 77.2% when stool culture and stx/Stx detection were combined with serology by LFIA. Our results demonstrate that the E. coli O157/O145 LFIA is a highly accurate and serospecific test for the early and rapid diagnosis of E. coli O157 and O145 infections in BD or HUS cases. This test allows the detection of specific IgM antibodies very early in the course of the infection, making it an ideal diagnostic tool to be implemented in pediatric emergencies and, thus, avoid delays in the application of the correct supportive or specific treatment and prevent complications associated with HUS.

Analytical measuring interval, linearity, and precision of serology assays for detection of SARS-CoV-2 antibodies according to CLSI guidelines.

Serology testing is commonly used to evaluate the immunogenicity of COVID-19 vaccines and measure antibodies as a marker of previous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, four laboratory-developed serology enzyme-linked immunosorbent assays (SARS-CoV-2 anti-Spike and anti-Nucleocapsid immunoglobin G [IgG] and immunoglobin M [IgM]) calibrated to the WHO International Standard 20/136 were validated via analytical measuring interval (limit of blank [LOB], limit of detection [LOD], and limit of quantification [LOQ]), linearity, and precision according to the Clinical and Laboratory Standards Institute (CLSI) guidelines EP17-A2, EP06 2nd Edition, and EP05-A3. For Spike IgG, LOB was 3.0 binding antibody units per milliliter (BAU/mL), LOD was 4.1 BAU/mL, and LOQ was 27.1 BAU/mL. For Nucleocapsid IgG, LOB was 1.9 BAU/mL, LOD was 3.2 BAU/mL, and LOQ was 24.6 BAU/mL. For Spike IgM, LOB was 57.1 BAU/mL, LOD was 69.0 BAU/mL, and LOQ was 113.5 BAU/mL. For Nucleocapsid IgM, LOD was 242.2 BAU/mL, LOD was 289.9 BAU/mL, and LOQ was 572.4 BAU/mL. Each assay displayed good linearity (max % deviation from linearity (≥LOQ) = 10.7%). The result of within-run repeatability evaluation for medium positive samples was 7.7% for Spike IgG, 4.6% for Nucleocapsid IgG, 7.5% for Spike IgM, and 10.1% for Nucleocapsid IgM. The total precision, including medium positive sample variability across 20 days, three reagent kits, and two operators, was 13.5% for Spike IgG, 14.5% for Nucleocapsid IgG, 17.6% for Spike IgM, and 16.2% for Nucleocapsid IgM. The assays were successfully validated following the applicable CLSI guidelines. All assays met the ±20% deviation from linearity and the ±20% coefficient of variation specification for precision and repeatability. IMPORTANCE: Reliable and validated serology assays are of increasing importance as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus continues to evolve and cause outbreaks. Validation of serology assays along with calibration to the International and National Standards (such as anti-SARS-CoV-2 Immunoglobulin WHO International Standard 20/136 or Frederick National Laboratory for Cancer Research's National Serology Standard COVID-NS01097) is critical to ensuring that results from clinical studies are reliable and comparable among various assays and laboratories. We describe the design and execution of a comprehensive study that established the analytical measuring intervals, linearity, precision, and repeatability of four in-house developed serology enzyme-linked immunosorbent assays (SARS-CoV-2 anti-Spike immunoglobin G [IgG] and immunoglobin M [IgM] and anti-Nucleocapsid IgG and IgM) following applicable Clinical and Laboratory Standards Institute (CLSI) guidelines. Overall, this study provides practical guidance on experimental design strategies and data analysis techniques, pertaining to the validation of COVID-19 serology assays according to CLSI guidelines, for use in clinical research studies.

Adaptive multi-epitope targeting and avidity-enhanced nanobody platform for ultrapotent, durable antiviral therapy.

Pathogens constantly evolve and can develop mutations that evade host immunity and treatment. Addressing these escape mechanisms requires targeting evolutionarily conserved vulnerabilities, as mutations in these regions often impose fitness costs. We introduce adaptive multi-epitope targeting with enhanced avidity (AMETA), a modular and multivalent nanobody platform that conjugates potent bispecific nanobodies to a human immunoglobulin M (IgM) scaffold. AMETA can display 20+ nanobodies, enabling superior avidity binding to multiple conserved and neutralizing epitopes. By leveraging multi-epitope SARS-CoV-2 nanobodies and structure-guided design, AMETA constructs exponentially enhance antiviral potency, surpassing monomeric nanobodies by over a million-fold. These constructs demonstrate ultrapotent, broad, and durable efficacy against pathogenic sarbecoviruses, including Omicron sublineages, with robust preclinical results. Structural analysis through cryoelectron microscopy and modeling has uncovered multiple antiviral mechanisms within a single construct. At picomolar to nanomolar concentrations, AMETA efficiently induces inter-spike and inter-virus cross-linking, promoting spike post-fusion and striking viral disarmament. AMETA's modularity enables rapid, cost-effective production and adaptation to evolving pathogens.

The evolution of flexibility and function in the Fc domains of IgM, IgY, and IgE.

Introduction: Antibody Fc regions harbour the binding sites for receptors that mediate effector functions following antigen engagement by the Fab regions. An extended "hinge" region in IgG allows flexibility between Fab and Fc, but in both the most primitive antibody, IgM, and in the evolutionarily more recent IgE, the hinge is replaced by an additional domain pair in the homodimeric six-domain Fc region. This permits additional flexibility within the Fc region, which has been exploited by nature to modulate antibody effector functions. Thus, in pentameric or hexameric IgM, the Fc regions appear to adopt a planar conformation in solution until antigen binding causes a conformational change and exposes the complement binding sites. In contrast, IgE-Fc principally adopts an acutely bent conformation in solution, but the binding of different receptors is controlled by the degree of bending, and there is allosteric communication between receptor binding sites. Methods: We sought to trace the evolution of Fc conformational diversity from IgM to IgE via the intermediate avian IgY by studying the solution conformations of their Fc regions by small-angle X-ray scattering. We compared four extant proteins: human IgM-Fc homodimer, chicken IgY-Fc, platypus IgE-Fc, and human IgE-Fc. These are examples of proteins that first appeared in the jawed fish [425 million years ago (mya)], tetrapod (310 mya), monotreme (166 mya), and hominid (2.5 mya) clades, respectively. Results and discussion: We analysed the scattering curves in terms of contributions from a pool of variously bent models chosen by a non-negative linear least-squares algorithm and found that the four proteins form a series in which the proportion of acutely bent material increases: IgM-Fc < IgY-Fc < plIgE-Fc < huIgE-Fc. This follows their order of appearance in evolution. For the huIgM-Fc homodimer, although none are acutely bent, and a significant fraction of the protein is sufficiently bent to expose the C1q-binding site, it predominantly adopts a fully extended conformation. In contrast, huIgE-Fc is found principally to be acutely bent, as expected from earlier studies. IgY-Fc, in this first structural analysis of the complete Fc region, exhibits an ensemble of conformations from acutely bent to fully extended, reflecting IgY's position as an evolutionary intermediate between IgM and IgE.

The immunoglobulin M-degrading enzyme of Streptococcus suis (IdeSsuis) leads to long-lasting inhibition of the activation of porcine IgM-secreting B cells.

Streptococcus suis (S. suis) is one of the most important porcine pathogens, causing severe pathologies such as meningitis or polyarthritis. It is also a very successful colonizer of mucosal surfaces. The IgM-degrading enzyme of S. suis (IdeSsuis) specifically cleaves porcine IgM, which results in complement evasion. On the basis of our previous finding that IdeSsuis also cleaves the IgM B cell receptor in vitro, we verified IgM B cell receptor cleavage ex vivo in whole regional lymph nodes and investigated the working hypothesis that this IgM B cell receptor cleavage results in a long-lasting impaired B cell function. The number of IgM-secreting cells was determined via ELISpot analysis after porcine peripheral blood mononuclear cells had initially been treated with different recombinant S. suis proteins and subsequently stimulated with interleukin-2 and the toll-like receptor 7/8 ligand R848. Compared with treatment with medium or recombinant muramidase-released protein, treatment with rIdeSsuis but also with a cleavage-deficient variant led to a reduction in the number of IgM-secreting cells as well as the level of secreted IgM. Flow cytometry analysis confirmed that the IgM B cell receptor was cleaved only by rIdeSsuis, and the receptor recovered to pretreatment levels on day 2 after treatment. Flow cytometry analysis of B and T cells incubated with fluorescein-labelled recombinant proteins revealed that different rIdeSsuis variants bind specifically to B cells, most prominently the cleavage-deficient variant. Our results indicate that in vitro interference of rIdeSsuis with the IgM B cell receptor results in long-lasting impaired IgM secretion by B cells after toll-like receptor activation. Further studies are warranted to prove that the modulation of B cell function by IdeSsuis could play a role in vivo.

Seroprevalence of brucellosis among high-risk individuals in Madinah, Saudi Arabia.

Background and Aim: Brucellosis is a highly contagious, neglected zoonotic disease of major importance worldwide. The disease is endemic in many countries, burdening healthcare systems and the livestock industry and representing a persistent public health concern in these countries. Brucellosis is considered an important occupational hazard for livestock workers. Limited studies have investigated human brucellosis in Saudi Arabia. Therefore, this study aimed to estimate the prevalence of brucellosis among employees of high-risk brucellosis professions, including veterinarians, animal herders, and abattoir workers in Madinah, Saudi Arabia, and to determine the associated risk factors. Materials and Methods: A cross-sectional study was conducted in Madinah, Saudi Arabia, during the period of January-March 2023. Ninety blood samples were collected from individuals occupationally at risk of exposure to Brucella infections. Serum samples were examined for immunoglobulins (Ig)M and IgG antibodies against Brucella using an indirect enzyme-linked immunosorbent assay. Before sample collection, a predesigned online questionnaire was used to collect the participants' sociodemographic characteristics and the probable risk factors for human brucellosis. A Chi-square test was used to compare the differences among groups; p < 0.05 were considered statistically significant. Results: Among the 90 participants among the high-risk individuals, Brucella IgM and IgG seropositivity were found in 8 (8.8%) and 11 (12.12%) cases, respectively. IgM mono antibody positivity was observed in 4 (4.44%) and 7 (7.77%) of the study population who tested positive for IgG only. Dual positivity for IgM and IgG antibodies was observed in 4 (4.44%) participants. No significant association was determined between seropositivity and age, urbanicity, education, occupation, and duration of exposure (p > 0.05). Conclusion: Brucellosis is a high-risk occupational disease among workers with close contact with livestock. This study demonstrates that the seroprevalence of brucellosis among occupationally high-risk individuals in Madinah, Saudi Arabia, is relatively low compared to other countries in the region. Nevertheless, educational programs should be implemented to improve knowledge regarding brucellosis, particularly among high-risk individuals.

Role of IgM/ IgG Ratio in Distinguishing Primary and Secondary Dengue Viral Infections: A Cross-Sectional Study.

Objectives In recent years, Uttarakhand, a state in North India has become one of the prime spots for tourism all over the world. Thereby, a tremendous increase in the epidemics of dengue infection has been observed recently. Secondary dengue causes more severe disease in comparison with primary, thus to differentiate the two is very crucial. We aim to find out the cut-off values of the IgM:IgG ratio for early detection of secondary dengue which could further help clinicians to prevent the complications. Methods A cross-sectional study was conducted over one year involving around 936 suspected cases of dengue. Samples were tested using the commercially available capture enzyme linked Immunosorbent assay (ELISA) method for IgM and IgG. Real-time and nested polymerase chain reaction (PCR) tests were also done to find out the prevalent serotype. IgM:IgG ratio was evaluated by using receiver operating characteristic curve analysis for the differentiation of primary and secondary dengue. Results Among the total 91 serologically confirmed dengue patients, forty-seven (51.6%) were found to be primary, and forty-four (48.4%) were secondary dengue infections with male preponderance. Using the WHO diagnostic criteria, patients with dengue fever (DF) without warning signs added up to 51.6%, with warning signs 42.9% and severe dengue 5.5% of the total cases. The cut-off ratio of IgM:IgG ratio = 1.59 found the best discrimination between primary and secondary infection. Forty out of ninety-one (44%) patients exhibited ratios of > 1.59 whereas the rest fifty-one (56%) exhibited ratios of < 1.59. Dengue virus - 2 (DENV- 2) was found to be the most prevalent serotype. Conclusion Our study recommends the cut-off values for IgM:IgG ratio as 1.59. Therefore it is hoped that this will guide the clinicians to early distinguish between primary and secondary dengue. Furthermore, it can reduce morbidity and mortality because of dengue infections in the future.

Detection of IgM antibodies against bovine viral diarrhea virus using IgM capture ELISA on farms with persistently infected cattle.

Bovine viral diarrhea (BVD) is a serious disease in cattle and causes economic losses in the livestock industry. Bovine viral diarrhea virus (BVDV) is the causative agent of BVD and spreads among herds via persistently infected (PI) animals that shed large amounts of the virus throughout their lives. Hence, identifying, and culling PI animals and assessing the immune status against BVDV on farms are important strategies for controlling BVD. Additionally, estimating the time when individuals around PI animals were infected with the virus could also be supportive information to interpret a farm status. We herein constructed a BVDV-specific IgM capture ELISA using recombinant E2 antigen and applied it to detecting BVDV-specific IgM antibodies on farms with identified PI cattle. The IgM ELISA detected anti-BVDV IgM antibodies during approximately 2-3 weeks post infection and identified IgM-positive cattle on two farms with recognized PI cattle. Virus neutralization tests showed that almost all adult cattle had high virus neutralization antibodies against BVDV, and sero-positive and -negative cattle coexisted in young herds. In this situation, most of the IgM-positive cattle were in relatively young animals, implying that BVDV had been recently spreading in these young herds. Thus, our findings demonstrated that detecting IgM antibodies could be useful to know recent BVDV infection on farm on which PI cattle were identified.

Maternal Cytomegalovirus (CMV) Serology: The Diagnostic Limitations of CMV IgM and IgG Avidity in Detecting Congenital CMV Infection.

INTRODUCTION: Congenital cytomegalovirus (cCMV) is a common congenital viral infection. Testing for cCMV usually begins with assessing maternal CMV serology, specifically IgM and IgG antibodies. A negative maternal CMV IgM suggests a low risk of recent maternal CMV infection, thereby suggesting a low risk of cCMV in the fetus. Consequently, cCMV is often ruled out when maternal CMV IgM is negative. METHODS: In our perinatal autopsy and placental pathology database, we identified 5 cases of cCMV despite negative maternal CMV IgM results in the second trimester. RESULTS: In all 5 cases, fetal abnormalities were first detected by ultrasound in the second trimester, prompting maternal CMV testing. Since second trimester maternal CMV IgM was negative in all cases, cCMV was considered unlikely, thus precluding further prenatal CMV testing in 4 of these cases. The diagnosis of cCMV was subsequently made through placental and/or autopsy examinations. Following this diagnosis, retrospective CMV serology and IgG avidity testing was performed on stored frozen first-trimester maternal blood samples in 3 cases. Among these, the first-trimester samples in 2 cases were IgG+, IgM+, and exhibited low IgG avidity, suggesting a primary maternal CMV infection around the time of conception. In the third case, both first and second-trimester maternal blood samples were IgG+, IgM-, and showed high IgG avidity, suggesting a non-primary maternal CMV infection (i.e., reactivation or reinfection of CMV). CONCLUSION: A negative maternal CMV IgM in the second trimester cannot exclude cCMV infection. While CMV IgG avidity testing and analysis of stored frozen first-trimester maternal blood samples provide valuable insights, they have limitations. CMV PCR performed on amniotic fluid is a useful prenatal diagnostic tool. For cases of unexplained fetal abnormalities or death, autopsy and placental examination are recommended.