IgM Reactivity Research Articles

Clones reactive to apoptotic cells and specific chemical adducts are prevalent among human thymic B cells

IntroductionThymus resident B cells were described more than 40 years ago. In early human life, these cells are found predominantly in the medulla and overwhelmingly display an unswitched IgM+ phenotype. The reactivity of thymic IgM B cells, however, is still unclear.MethodsHere, we generated 120 IgM-producing B cell clones from 3 separate thymus specimens obtained from infant, adolescent, and adult donors. Using flow cytometry and a unique high-dimensional ELISA platform, we investigated the clones’ reactivity to apoptotic cells as well as to common chemical adducts exposed on modified amino acids and other macromolecules.ResultsRegardless of the age, approximately 30-40% of thymic IgM B cells reacted to apoptotic cells. Further, 30-40% displayed reactivity to at least one adduct, including malondialdehyde, Homocysteine, and NEDD 8. Four distinct reactivity patterns were identified through this profiling. Notably, a significant association was observed between reactivity to apoptotic cells, and to one or more adducts, suggesting that the same determinants were recognized in both assays. Additionally, thymic IgM B cells reactive to adducts were more likely to recognize intra-nuclear or intra-cytoplasmic structures in Hep-2 cells as revealed by immunofluorescence staining.Conclusion/DiscussionCollectively, our findings suggest that thymic IgM B cells actively uptake apoptotic bodies and cellular debris in the medulla by binding specific chemical adducts. This mechanism could underpin their antigen-presenting function and further support their role in T-cell negative selection.

Evaluation of different standard and modified two-tier testing strategies for the laboratory diagnosis of lyme borreliosis in a European setting.

Diagnosis of Lyme borreliosis (LB) relies on clinical symptoms and detection of Borrelia-specific antibodies. Guidelines recommend a two-tier testing (TTT) strategy for disseminated LB: serological screening with a sensitive enzyme immunoassay (EIA) and confirmation with a specific immunoblot. Searching for the most sensitive and specific approach, this retrospective study evaluated standard (STTT) and modified (MTTT) strategies using a well-defined study population. Cases included patients with active Lyme neuroborreliosis (LNB; n = 29) or Lyme arthritis (LA; n = 17). Controls comprised patients treated for LNB (n = 36) or LA (n = 8), healthy individuals who were either untreated (n = 75) or treated for LB (n = 15) in the past, and patients with potentially cross-reactive diseases (n = 16). Sera were subjected to three EIAs and two immunoblots. Reactive screening results were confirmed by immunoblot (STTT) or EIA (MTTT). Solitary IgM results in the screening assay and effects of antibiotic treatment on isotype-specific seropositivity rates were also assessed. Sensitivities of STTT strategies ranged from 90%-97% for LNB and were 100% for LA. MTTT strategies were 100% sensitive. Specificities ranged from 89%-95% for STTT and from 88%-93% for MTTT strategies. Differences between STTT and MTTT strategies were not statistically significant. Solitary IgM reactivity was common among controls. Antibiotic treatment significantly reduced IgM/IgG positivity for LNB patients; for LA patients, a decline was only observed for IgM. In conclusion, MTTT strategies showed a slightly higher sensitivity and similar specificity compared to STTT strategies. Since EIAs are more time- and cost-efficient, MTTT strategies seem more favorable for clinical use. IgG testing enhances specificity with minimal sensitivity loss.

Distinct groups of autoantigens as drivers of ocular adnexal MALT lymphoma pathogenesis.

Chronic B-cell receptor signals incited by cognate antigens are believed to play a crucial role in the pathogenesis of mucosa-associated lymphoid tissue lymphomas. We have explored the immunoglobulin variable regions (IGHV) expressed by 124 ocular adnexal MALT lymphomas (OAML) and tested the in vitro reactivity of recombinant IgM derived from 23 OAMLs. Six of 124 OAMLs (5%) were found to express a high-affinity stereotyped rheumatoid factor. OAMLs have a biased IGHV4-34 usage, which confers intrinsic super auto-antigen reactivity with poly-N-acetyllactosamine (NAL) epitopes, present on cell surface glycoproteins of erythrocytes and B cells. Twenty-one OAMLs (17%) expressed IGHV4-34-encoded B-cell receptors. Five of the 23 recombinant OAML IgMs expressed IGHV4-34, four of which bound to the linear NAL i epitope expressed on B cells but not to the branched NAL I epitope on erythrocytes. One non-IGHV4-34-encoded OAML IgM was also reactive with B cells. Interestingly, three of the 23 OAML IgMs (13%) specifically reacted with proteins of U1-/U-snRNP complexes, which have been implicated as cognate-antigens in various autoimmune diseases such as systemic lupus erythematosus and mixed connective tissue disease. The findings indicate that local autoimmune reactions are instrumental in the pathogenesis of a substantial fraction of OAMLs.

Evolución de la seroprevalencia de COVID-19 en bancos de sangre durante la pandemia en la región Lima, Perú

Introduction. Peru was one of the countries most affected by the COVID-19 pandemic, with more than 220,000 deaths recorded due to SARS-CoV-2 infection. Given the constant mutations of the virus and registered variants, it is important to carry out research that reflects the evolution of the humoral immune state. Objective. Measure the seroprevalence of COVID-19 during the pandemic in the department of Lima in the period between April 1, 2020 and June 30, 2022, in donor samples from 6 hospital blood banks public of Lima, Peru. Methods. A descriptive, transversal, observational and retrospective study was carried out evaluating the presence of IgM/IgG antibodies against SARS-CoV-2 using lateral flow chromatographic immunoassay in samples from healthy and asymptomatic donors from blood banks of 6 health facilities in the department of Lima. Results. A progressive increase in the seroprevalence of IgG and total reactivity of IgM/ IgG antibodies against SARS-CoV-2 will be observed as follows: 22,6% - 32,7% during 2020; 53,9% - 58,1% during 2021; 88,9% - 93,3% during the first half of 2022. Conclusions. The reactivity and presence of anti- SARS-CoV-2 antibodies progressively increase during the COVID-19 pandemic from 11,2% to 98,4% in the samples evaluated, possibly with the impact of the pandemic waves and the active vaccination campaign against COVID-19.

Discovery of a Unique Set of Dog-Seroreactive Coccidioides Proteins Using Nucleic Acid Programmable Protein Array.

Valley Fever (VF), caused by fungi in the genus Coccidioides, is a prevalent disease in southwestern and western parts of the United States that affects both humans and animals, such as dogs. Although the immune responses to infection with Coccidioides spp. are not fully characterized, antibody-detection assays are used in conjunction with clinical presentation and radiologic findings to aid in the diagnosis of VF. These assays often use Complement Fixation (CF) and Tube Precipitin (TP) antigens as the main targets of IgG and IgM reactivity, respectively. Our group previously reported evidence of over 800 genes expressed at the protein level in C. posadasii. However, antibody reactivity to the majority of these proteins has never been explored. Using a new, high-throughput screening technology, the Nucleic Acid Programmable Protein Array (NAPPA), we screened serum specimens from dogs against 708 of these previously identified proteins for IgG reactivity. Serum from three separate groups of dogs was analyzed and revealed a small panel of proteins to be further characterized for immuno-reactivity. In addition to CF/CTS1 antigen, sera from most infected dogs showed antibody reactivity to endo-1,3-betaglucanase, peroxisomal matrix protein, and another novel reactive protein, CPSG_05795. These antigens may provide additional targets to aid in antibody-based diagnostics.

A Mystery Unsolved: A Spontaneous Lens and Uveal Prolapse in a New-born

Introduction : Corneal rupture in new-born, especially during the first week of life is rare. Some of these cases occur because of ocular trauma during deliveries, systemic infection, and congenital anomalies. We aim to deliver a rare case of spontaneous lens and uveal prolapse in new-born and management in treating the case.
 Case Illustration : A-2-day-old full-term-baby was referred due to bleeding of the right eye 6 hours post-partum by spontaneous vaginal delivery with no trauma. The mother, a 23-year-old, having the second born with no history of medical illness or vaginal discharged during pregnancy. Measurements of birth weight and length were normal. Eye examination of the right eye (RE) was uveal and lens prolapse and left eye (LE) cloudy cornea with leukoma and prominent neovascularization. Orbital CT-Scan revealed bilateral vitreous bleeding of both eyes. Laboratory examination showed reactive IgM for herpes simplex virus, reactive IgG for both toxoplasma and rubella. Corneal swab culture was sterile. Systemic and topical antibiotics were administered then switched to systemic antivirus. The 12-day-old-patient showed partial epithelization of cornea, less uveal volume with it partially shrank. Close observation was conducted and evisceration was postponed.
 Discussion : Although etiologic work-up has been addressed, exact etiology remains unknown with the possibility of congenital cause. It has been postulated that structurally malformed eyes are more prone to corneal perforations. Management should be personalized based on the patient’s need.
 Conclusion : Thorough examination is vital a rare case with undisclosed aetiology especially new-born. Patient monitoring is sufficient if no infections and bleedings found.

Detection of Toxoplasma gondii Parasite on Blood Donor at PMI Kabupaten Magelang by Rapid Diagnostic Methods in 2022

Toxoplasma gondii is a parasite that can infect most warm-blooded animals, including humans. The infection is caused by Toxoplasma gondii called Toxoplasmosis. Toxoplasmosis transmission can occur because of human behaviour’s such as keeping cats, eating raw vegetables and fruit with a less clean, not washing hands properly, and consuming food and drinks served without lids that could potentially be contaminated with oocysts, as well as soil-related work such as gardening and farming. Toxoplasma gondii is an infectious parasite that could be transmitted through blood transfusions. The aim of this research was to detect IgM and IgG antibodies of Toxoplasma gondii in blood donors by Rapid Diagnostic method at PMI Kabupaten Magelang. This research is a descriptive observational with a cross sectional design and used 25 respondents with blood categories A, B, O, and AB at PMI Kabupaten Magelang in 2022. According to the results of the Toxoplasmosis examination utilizing the Rapid Diagnostic Test technique on blood donors at PMI Kabupaten Magelang, as many as 25 respondents obtained non-reactive IgM and IgG antibodies against Toxoplasma gondii. It could be concluded that no respondents were found to have reactive IgM and IgG antibodies against Toxoplasma gondii.

Study of the Immune Response of COVID-19 Patients in Kirkuk Province

Abstract Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a novel coronavirus causing coronavirus disease 2019 (COVID-19); it is diagnosed based on clinical signs and laboratory detection methods such as polymerase chain reaction (PCR) and serological techniques. Objective: The objective of the study is to use other diagnostic methods that support the PCR method of diagnosis for COVID-19. Materials and Methods: The study included 90 COVID-19 patients and 26 control group. Nasopharyngeal swabs were collected from the suspected patients with COVID-19 infection for the detection of the RNA virus by PCR technique. If the PCR was positive, the serum samples were collected and used for the quantitative detection of SARS-CoV-2 S1 (IgM, IgG) by using enzyme linked immunosorbent assay. Results: The result of this study showed that in a total of 116 participants, there was a significant difference between IgM and IgG reactivity (±) and the number of PCR-positive and negative individuals with P value <0.0001 and P value = 0.003, respectively. In addition, a significant increase in the levels of IgM and IgG (P ≤ 0.0001 for IgM and P ≤ 0.0001 for IgG) was recorded in patients compared with healthy control. Moreover, a significant correlation between IgM level with P = 0.0018 and the onset of symptoms as well as positive correlation was noticed between IgG concentration and the onset of symptoms (P = 0.0272). Conclusion: The study concluded that antibodies developed against COVID-19 infection could appear at early stages of the infection without the confirmation of real time polymerase chain reaction, and this could be a beneficial tool for early screening of suspected as well as asymptomatic individuals.

Autoantibody repertoire profiling in tissue and blood identifies colorectal cancer-specific biomarkers.

Autoantibodies (AAbs) in the blood of colorectal cancer (CRC) patients have been evaluated for tumor detection. However, it remains uncertain whether these AAbs are specific to tumor-associated antigens. In this study, we explored the IgG and IgM autoantibody repertoires in both the insitu tissue microenvironment and peripheral blood as potential tumor-specific biomarkers. We applied high-density protein arrays to profile AAbs in the tumor-infiltrating lymphocyte supernatants and corresponding serum from four patients with CRC, as well as in the serum of three noncancer controls. Our findings revealed that there were more reactive IgM AAbs than IgG in both the cell supernatant and corresponding serum, with a difference of approximately 3-5 times. Immunoglobulin G was predominant in the serum, while IgM was more abundant in the cell supernatant. We identified a range of AAbs present in both the supernatant and the corresponding serum, numbering between 432 and 780, with an average of 53.3% shared. Only 4.7% (n = 23) and 0.2% (n = 2) of reactive antigens for IgG and IgM AAbs, respectively, were specific to CRC. Ultimately, we compiled a list of 19 IgG AAb targets as potential tumor-specific AAb candidates. Autoantibodies against one of the top candidates, p15INK4b-related sequence/regulation of nuclear pre-mRNA domain-containing protein 1A (RPRD1A), were significantly elevated in 53 CRC patients compared to 119 controls (p < 0.0001). The project revealed that tissue-derived IgG AAbs, rather than IgM, are the primary source of tumor-specific AAbs in peripheral blood. It also identified potential tumor-specific AAbs that could be applied for noninvasive screening of CRC.

Alpha-7 Nicotinic Acetylcholine Receptor Activation Inhibits Trauma Induced Pronociceptive Autoimmune Responses

Both autonomic nervous system dysfunction and immune system activation are characteristic of chronic pain after limb injuries. Cholinergic agonists reduce immune system activation in many settings. We hypothesized, therefore, that alpha-7 nicotinic acetylcholine receptor (α7nAChR) agonist administration would reduce nociceptive and immune changes after tibia fracture and cast immobilization in mice. Fracture mice were treated with either vehicle, a low (.2 mg/kg) dose, or a high (1 mg/kg) dose of the selective α7nAChR agonist PNU-282987 for 4 weeks. We assessed hindpaw allodynia and weight bearing as behavioral outcomes. The assessment of adaptive immune responses included regional lymph node hypertrophy, germinal center formation, α7nAChR expression, and IgM deposition. Assessment of innate immune system activation focused on IL-1β and IL-6 generation in fractured hindlimb skin. We observed that mechanical allodynia and unweighting were alleviated by PNU-282987 treatment. Drug treatment also reduced popliteal lymph node hypertrophy and germinal center formation. Immunohistochemical studies localized α7nAChR to germinal center B lymphocytes, and this expression increased after fracture. Analysis of fracture limb hindpaw skin demonstrated increased inflammatory mediator (IL-1β and IL-6) levels and IgM deposition, which were abrogated by PNU-282987. Serum analyses demonstrated fracture-induced IgM reactivity against keratin 16, histone 3.2, GFAP, and NMDAR-2B. Administration of PNU-282987 reduced the enhancement of IgM reactivity. Collectively, these data suggest that the α7nAChR is involved in regulating posttraumatic innate and adaptive immune responses and the associated nociceptive sensitization. PerspectiveThese studies evaluate the effects of a selective α7nAChR agonist in a tibial fracture/cast immobilization model of limb pain. Administration of the drug reduced nociceptive and functional changes 4 weeks after injury. These novel findings suggest that well-tolerated α7nAChR agonists may be viable analgesics for chronic pain after limb injuries.

Novel CD123xCD3 Bispecific Igm Antibody, Igm-2537, Potently Induces T-Cell Mediated Cytotoxicity of Acute Myeloid Leukemia Cells In Vivo and in Vitro with Minimal Cytokine Release

Introduction: New therapeutics are needed for the effective treatment of acute myeloid leukemia (AML), as standard chemotherapeutics are poorly tolerated and ~50% of patients relapse primarily due to the incomplete elimination of leukemia stem cells (LSCs). CD123, the IL-3Rα chain, is highly expressed on leukemic blasts and LSCs, and is further increased in patients with poor prognostic factors. Bispecific T-cell engager (TCE) antibodies and CAR-T cells targeting CD123 have shown promising clinical efficacy in AML patients, but cytokine release syndrome limits their therapeutic window and remains a major safety concern. IGM-2537 is a novel pentameric IgM bispecific TCE antibody engineered with ten anti-CD123 binding sites, and an anti-CD3ε single chain Fv domain fused to the joining chain to engage T-cells. Here, we report that IGM-2537 not only potently induces T-cell mediated cytolytic killing of AML cells in vitro and in vivo but also demonstrates minimal cytokine release, and little to no effect on normal hematopoietic progenitor cells and human vascular endothelial cells (HUVECs) with in vitro and ex vivo studies. Additionally, an improved tolerability, excellent pharmacodynamic (PD) response and lower cytokine release was observed with a cynomolgus cross-reactive IgM TCE in monkeys. Materials and Methods:Surface plasma resonance (SPR), cell membrane protein array, and alanine scanning were utilized to characterize human CD123 binding affinity, specificity and epitope mapping, respectively. T-cell dependent cellular cytotoxicity (TDCC) assays were employed to evaluate the potency of IGM-2537 target cytotoxicity, T cell activation and cytokine release. Ex vivo AML colony formation assays were used to assess the activity on AML blasts. Human MV-4-11 and MOLM-13 xenograft tumor models in humanized NSG dKO mice were utilized to determine in vivo anti-tumor activity of IGM-2537. Healthy human PBMCs and bone marrow (BM) samples as well as HUVECs were used in ex vivo assays to address potential safety concerns of IGM-2537 mediated effects on hematopoietic progenitor cells and HUVECs, respectively. Lastly, to confirm that a CD123 directed IgM-based TCE molecule can potentially provide better safety profile in vivo, a cynomolgus-cross reactive IgM TCE comparator was assessed in monkeys for tolerability and PK/PD responses. Results and Conclusions: IGM-2537 bound with high affinity and avidity to CD123. In vitro, IGM-2537 engaged both CD123 and CD3 to induce potent T-cell activation and T-cell mediated cytotoxicity of CD123 + AML cells, and autologous CD123 + basophils and plasmacytoid dendritic cells (pDCs). Though IGM-2537 demonstrated comparable maximal killing activity to a comparator IgG TCE, IGM-2537 demonstrated minimal cytokine release. In ex vivo patient-derived AML or normal BM colony formation assays, IGM-2537 eliminated AML colony forming cells at physiologically relevant effector/target (E/T) ratios but had little or no effect on normal hematopoietic progenitors. In addition, IGM-2537 demonstrated no cytotoxicity against HUVECs regardless of their CD123 expression at basal levels or at maximal levels upregulated by TNF-a and IFN-g, in contrast to a comparator IgG TCE. In vivo, IGM-2537 completely inhibited tumor growth in two AML xenograft tumor models, a subcutaneous MV-4-11 model, and a systemic MOLM-13 model in humanized NSG dKO mice. To further evaluate the potency and safety of the CD123xCD3 IgM bispecific TCE format in vivo, a cynomolgus cross-reactive CD123xCD3 IgM bispecific TCE was evaluated for tolerability and PD responses in cynomolgus monkeys using single doses. All animals tolerated the cross-reactive bispecific IgM TCE well at doses up to 10 mg/kg (the maximal dose level evaluated), a dose 100-fold greater than published doses of a comparator IgG TCE. Complete depletion of CD123 + basophils and substantial reductions of pDCs were seen in blood and BM with minimal to no cytokine induction. In summary, IGM-2537 demonstrated potent in vitro and in vivo T-cell mediated cytotoxicity of AML cell lines with minimal cytokine induction. The encouraging preclinical safety profiles were further supported by little/no effect on normal hematopoietic progenitor cells and HUVECs. These preclinical data support the clinical development of IGM-2537 for the treatment of AML and other hematological malignancies.

Autoimmune PaneLs as PrEdictors of Toxicity in Patients TReated with Immune Checkpoint InhibiTors (ALERT)

BackgroundImmune-checkpoint inhibitors (ICI) can lead to immune-related adverse events (irAEs) in a significant proportion of patients. The mechanisms underlying irAEs development are mostly unknown and might involve multiple immune effectors, such as T cells, B cells and autoantibodies (AutoAb).MethodsWe used custom autoantigen (AutoAg) microarrays to profile AutoAb related to irAEs in patients receiving ICI. Plasma was collected before and after ICI from cancer patients participating in two clinical trials (NCT03686202, NCT02644369). A one-time collection was obtained from healthy controls for comparison. Custom arrays with 162 autoAg were used to detect IgG and IgM reactivities. Differences of median fluorescent intensity (MFI) were analyzed with Wilcoxon sign rank test and Kruskal–Wallis test. MFI 500 was used as threshold to define autoAb reactivity.ResultsA total of 114 patients and 14 healthy controls were included in this study. irAEs of grade (G) ≥ 2 occurred in 37/114 patients (32%). We observed a greater number of IgG and IgM reactivities in pre-ICI collections from patients versus healthy controls (62 vs 32 p < 0.001). Patients experiencing irAEs G ≥ 2 demonstrated pre-ICI IgG reactivity to a greater number of AutoAg than patients who did not develop irAEs (39 vs 33 p = 0.040). We observed post-treatment increase of IgM reactivities in subjects experiencing irAEs G ≥ 2 (29 vs 35, p = 0.021) and a decrease of IgG levels after steroids (38 vs 28, p = 0.009).ConclusionsOverall, these results support the potential role of autoAb in irAEs etiology and evolution. A prospective study is ongoing to validate our findings (NCT04107311).

Outbreak-Associated Cases Of Human Hepatitis Viruses (HAV, HBV &amp; HCV) With Herpes Simplex Virus And HIV Infections Detected in Blood-Based Biomarkers

Hepatitis A vaccines are based on classic first-generation inactivated virus vaccines and have been developed by different biopharmaceuticals. HAV is found in the stool, blood of people who are infected and foodborne hepatitis. HBV is a short-term disease and is one of the major causative agents of chronic liver illness. For others, it can become a long-term, chronic infection like liver disease or liver cancer. The analysis of genomic variability of HBV isolates is fundamental for molecular and epidemiological studies. HCV has a higher rate of mutation existing inside an individual as quasispecies. In this sense, this study addresses an analysis of viral hepatitis A/B/C, Herpervirus Simplex (HSV) type 1/2 and the human immunodeficiency virus (HIV) as topics related to comprehensive care for people with sexually transmitted infections (STIs). A total of 2.750 samples were collected from 2.713 patients, of which 38,43% were for HCV; 31,20% for HIV research; 30,25% for HAV and 0,10% for HSV. In all, eight biomarkers of the hepatitis B virus (HBV) were investigated, of which the HBsAg marker was non-reactive in 44,01% (2022 y) and 47.66% (2023 y). About 31,41% (2022 y) and 31.99% (2023y) were reactive for anti-HBs. The highest percentage of investigated samples (98.38%) was recorded in March 2022 with a average proportion of 55.25 ± 12.96 (CV = 0.234) for the non reactive IgM biomarker. The authors suggest follow-up with new serological research associated with molecular assays aimed specifically at reactive and inconclusive results.

Evaluation of isotype-based serology for diagnosis of Schistosoma mansoni infection in individuals living in endemic areas with low parasite burden

Intestinal schistosomiasis is a chronic and debilitating disease that affects public health systems worldwide. Control interventions to reduce morbidity primarily involve the diagnosis and treatment of infected individuals. However, the recommended Kato-Katz (KK) parasitological method shows low sensitivity in individuals with low parasite loads and is not useful for monitoring elimination of parasite transmission at later stages. In the current study, we evaluated the accuracy of serum reactivity levels of different immunoglobulin isotypes in an enzyme-linked immunosorbent assay (ELISA), utilizing Schistosoma mansoni crude extracts, with the aim to improve the diagnosis of infected individuals with low parasite loads. The serum reactivity of IgM and IgG subclass antibodies (IgG1, IgG3, and IgG4) against soluble adult worm and egg antigen preparations was evaluated in residents from a schistosomiasis-endemic area in northern Minas Gerais, Brazil. The parasitological status of the study population was determined through fecal examination with multiple parasitological tests to create a consolidated reference standard (CRS) plus a fecal DNA detection test (q-PCR). Twelve months after praziquantel treatment, a second serum sample was obtained from the population for reexamination. A two-graph receiver operating characteristic curve (TG-ROC) analysis was performed using the serum reactivity of non-infected endemic controls and egg-positive individuals, and the cut-off value was established based on the intersection point of the sensibility and specificity curves in TG-ROC analyses. The diagnostic accuracy of each serological test was evaluated in relation to the parasitological CRS and to the combination of CRS plus qPCR results. The data revealed that serum reactivity of IgM and IgG3 against S. mansoni antigens did not allow identification of infected individuals from the endemic area. In contrast, serum IgG1 and IgG4-reactivity against schistosome antigens could distinguish between infected and non-infected individuals, with AUC values ranging between 0.728–0.925. The reactivity of IgG4 anti-soluble egg antigen - SEA (sensitivity 79 %, specificity 69 %, kappa = 0.49) had the best diagnostic accuracy, showing positive reactivity in more than 75 % of the infected individuals who eliminated less than 12 eggs per gram of feces. Moreover, serum IgG4 reactivity against SEA and against soluble worm antigen preparation (SWAP) was significantly reduced in the serum of infected individuals after 12 months of confirmed parasitological cure and in the absence of re-infection. These results reinforce that the described IgG4 anti-SEA ELISA assay is a sensitive alternative for the diagnosis of active intestinal schistosomiasis in individuals from endemic areas, including in those with a very low parasite load.

Exploring the dynamics of Borrelia burgdorferi sensu lato antibodies—a registry-based study on laboratory data from Sweden and Denmark

ObjectivesLyme borreliosis (LB) is the most common tick-transmitted infection in the northern hemisphere and is caused by bacteria in the Borrelia burgdorferi sensu lato (Bbsl)-complex. The diagnosis is partially based on serology, and clinicians often take follow-up serum samples to look for seroconversion or an increase in IgG-antibody levels. In this registry-based study, we proposed a method for determining actual changes in IgG and examined antibody reactivity and decay. MethodsSerological data from the departments of clinical microbiology at Karlstad Hospital, Sweden, and Slagelse Hospital, Denmark, were used to calculate a seroreactivity cut-off (SCOFF), above which changes between two samples from the patient cannot be explained by random variation. Increases in IgG reactivity as well as IgG and IgM decay were illustrated using time-to-event analysis and the SCOFF. ResultsA total of 44,861 serum samples from 34,157 patients were tested for Bbsl-antibodies. Of the 4301 patients with follow-up samples taken within 100 days, 201 (4.67%) were above the SCOFF of 1.42 with a median time to follow-up sample of 36 days (interquartile range: 21). IgG demonstrated longer median time for all antibody levels (indeterminate: 4.6 years, low: 7.0 years, moderate-high: 8.8 years) than IgM antibodies (indeterminate: 2.1 years, low: 3.9 years, moderate-high: 6.8 years) and higher initial antibody levels persisted significantly longer for both IgG and IgM antibodies (p < 0.001). Of the 7868 patients with follow-up samples, isolated IgM reactivity preceded an increase in IgG reactivity in 18 patients (0.23%). DiscussionThe SCOFF indicated little biological and random variation for Bbsl-specific IgG antibodies on the platforms used during the study. In most follow-up samples, both IgG and IgM antibodies persisted for years, with longer seropositivity associated with high initial antibody levels and IgG-type antibodies. The diagnostic value of isolated IgM reactivity was limited.

Seroprevalence of SARS-CoV-2(Covid-19) Antibody Among Blood Donors in a Tertiary Care Centre in South India

Introduction The novel severe acute respiratory syndrome virus 2 (SARS-CoV-2), which is responsible Coronavirus disease (COVID-19), spread worldwide from China, causing a pandemic from late December 2019. Due to the high proportion of asymptomatic or mild infections (approximately 80%), data restricted to laboratory-confirmed cases do not capture the true extent of the spread or burden of the virus, or its infection-fatality ratio. Therefore, serological detection of specific antibodies against SARS-CoV-2 can better estimate the true number of infections. The current study aims to estimate the seroprevalence of SARS-CoV-2 antibodies among the whole blood donors without any prior COVID-19 history or symptoms. Objective To determine seroprevalence of SARS-CoV-2 (COVID-19) antibody (IgG and IgM) among asymptomatic healthy blood donors. Methods This was a cross sectional study conducted between March and July, 2021 among 300 blood donors without any prior COVID-19 history or symptoms who came to a tertiary care, multispecialty hospital in south India. Any donor who had recently travelled abroad or donors who had received COVID-19 vaccine are excluded from the study. 3 ml venous blood was drawn in EDTA tube from participants and was tested by “Access SARS CoV-2 IgG assay” and “Access SARS CoV-2 IgM assay” by UniCel DxI 800 Immunoassay analyzer (Beckman coulter). The Access SARS CoV-2 IgG assay and the Access SARS Cov-2 IgM assay detect antibodies to the Receptor Binding Domain (RBD) of the Spike Protein. Result was reported as Reactive if Signal/Cut-off (S/CO)&gt;1.0 and non-Reactive if S/CO &lt;1. Data was collected and entered into excel sheets and was analyzed by using the software SPSS version 25. Results A total of 300 healthy blood donors were included. The study reported seroprevalence of 15.3% for IgG and 4.3% for IgM (95%CI) among asymptomatic whole blood donors. No significant difference was observed across age groups, diet, BMI, ABO/Rh blood type or Ayurveda/homeo immune medicine intake with respect to IgG and IgM reactivity. Conclusion 15% of blood donors were seroconverted for COVID-19 during second wave. This reflects widespread seroprevalence in the adult population. Real-time seroprevalence studies will help to know the herd immunity among the blood donors which will assist in knowing the COVID-19 transmission dynamics and distribution of immunity levels at a particular point in time.

Construction, Expression, and Evaluation of the Naturally Acquired Humoral Immune Response against Plasmodium vivax RMC-1, a Multistage Chimeric Protein.

The PvCelTOS, PvCyRPA, and Pvs25 proteins play important roles during the three stages of the P. vivax lifecycle. In this study, we designed and expressed a P. vivax recombinant modular chimeric protein (PvRMC-1) composed of the main antigenic regions of these vaccine candidates. After structure modelling by prediction, the chimeric protein was expressed, and the antigenicity was assessed by IgM and IgG (total and subclass) ELISA in 301 naturally exposed individuals from the Brazilian Amazon. The recombinant protein was recognized by IgG (54%) and IgM (40%) antibodies in the studied individuals, confirming the natural immunogenicity of the epitopes that composed PvRMC-1 as its maintenance in the chimeric structure. Among responders, a predominant cytophilic response mediated by IgG1 (70%) and IgG3 (69%) was observed. IgM levels were inversely correlated with age and time of residence in endemic areas (p < 0.01). By contrast, the IgG and IgM reactivity indexes were positively correlated with each other, and both were inversely correlated with the time of the last malaria episode. Conclusions: The study demonstrates that PvRMC-1 was successfully expressed and targeted by natural antibodies, providing important insights into the construction of a multistage chimeric recombinant protein and the use of naturally acquired antibodies to validate the construction.

Utility of Borrelia-specific IgM and IgG antibody titer determinations during a 12-year period - results from a clinical laboratory in Northern Sweden.

Interpretation of serological findings in suspected Lyme borreliosis (LB) is challenging and IgM reactivities may have low predictive value. Therefore, if used indiscriminately, there is a risk for incorrect diagnosis of LB. To evaluate the usefulness of IgM titer determination, we performed a study of the prevalence of Borrelia-specific antibodies in serological samples from patients with suspected LB analyzed during the period 2010 - 2021 at the University Hospital of Umeå in Sweden. In total, 19,335 samples had been analyzed for the presence of IgG and IgM antibodies. Overall, there were higher percentages of IgM positive or borderline titers, 1,847 (9.6%) and 905 (4.7%), respectively, than IgG positive or borderline titers, 959 (5.0%) and 406 (2.1%), respectively. Peak number of samples were recorded 2012 - 2013, exceeding 1,800, whereas there were around 1,200 during 2020 - 2021. The peak number of positive IgG and/or positive IgM samples were observed during the period 2015 - 2017 with close to, or above 400, and concomitantly, the proportion of IgG positive samples increased markedly. For IgG positive samples, the increase followed a positive linear time trend (P< 0.001). Peak monthly numbers were observed during August, September, and October. This seasonal increase was significant for the IgG positive group (P< 0.05), but not for the IgM positive/IgG negative group. Repeated samples were obtained from 3,188 individuals and of the initial samples 2,817 were (88%) IgG negative and 2,315 (72%) were IgM negative and of these, 130 (4%) showed IgG seroconversion and 300 (9%) IgM seroconversion. Collectively, the data demonstrate that IgG and/or IgM positive samples represented a minority of all samples, even when repeated sampling had occurred, and IgM positive samples were much more common than IgG positive samples. Thus, the accuracy of the clinical suspicion was low and this will lead to a low predictive value of the analysis, in particular of IgM. These findings question the use of IgM titer determination as a routine analysis.

Classical Borrelia Serology Does Not Aid in the Diagnosis of Persistent Symptoms Attributed to Lyme Borreliosis: A Retrospective Cohort Study.

The diagnosis of Lyme borreliosis is based on two-tier testing using an ELISA and Western blot. About 5-10% of patients report persistent symptoms of unknown etiology after treatment, resulting in substantial difficulties in further diagnostic workup. This paper presents a study aimed at determining whether serology can differentiate between patients with persistent symptoms attributed to Lyme and other patients with Lyme borreliosis. A retrospective cohort study included 162 samples from four subgroups: patients with persistent symptoms of Lyme (PSL), early Lyme borreliosis with erythema migrans (EM), patients tested in a general practitioner setting (GP), and healthy controls (HC). ELISA, Western blots, and multiplex assays from different manufacturers were used to determine inter-test variations in PSL and to compare reactivity against Borrelia-specific antigens among the groups. In comparing the IgG and IgM reactivity by Western blot, IgG was more often positive in the PSL group than in the GP group. The individual antigen reactivity was similar between the PSL and EM or GP groups. Inter-test agreement among the manufacturers was variable, and agreement was higher for IgG testing compared to IgM. Serological testing is unable to define the subgroup of patients with persistent symptoms attributed to Lyme borreliosis. Additionally, the current two-tier testing protocol shows a large variance among different manufacturers in these patients.

Analysis of naturally acquired immune responses against the Plasmodium falciparummalaria vaccine candidate PF3D7_1136200

Abstract Humoral immunity is critical for protection against Plasmodium falciparum malaria. In endemic areas, individuals acquire protective immunity against malaria through repeated exposure to P. falciparum parasites. Understanding these naturally acquired immune responses would be highly informative for the development of improved vaccination strategies against malaria. Antibody responses against the uncharacterized protein PF3D7_1136200 correlate with protection from malaria, however, the development of these antibody responses over time and their role in protecting against malaria remain unknown. Here, we compared PF3D7_1136200-specific antibody and B cell responses to that of other P. falciparum antigens in Ugandan individuals with different immune status: immune adults (n=24) and children with high (n=10) or low (n=8) susceptibility to malaria. In all groups, serum antibody reactivity against MSP1, MSP3, AMA1, VFT, Pf41, and Pf113 was dominated by IgG. In contrast, serum IgG antibody reactivity against PF3D7_1136200 was much lower, while IgM reactivity was at a similar or higher level compared to these antigens. In line with the low serum IgG reactivity against PF3D7_1136200 among adults, we exclusively observed IgM +memory B cells (MBCs) against PF3D7_1136200, while IgG +MBCs were more abundant than IgM +MBCs for all other antigens. These results indicate that PF3D7_1136200 has a low antigenic profile, similar to that of other favorable P. falciparum vaccine candidates, and suggest potential shielding of antigen from the host immune system. Together with the genetic conservation of PF3D7_1136200, these characteristics highlight that Pf3D7_1136200 has potential as a novel vaccine candidate against malaria. Supported by grants from NIH (R01 AI153425, P30 CA054174-20)