Search Results (1,569)

Background/Objectives: Syphilis, a chronic sexually transmitted disease caused by the spirochete Treponema pallidum subspecies pallidum (T. pallidum), is still endemic in low- and middle-income countries and has been resurgent for decades in many high-income nations despite being treatable. Improving our understanding of syphilis pathogenesis, immunology, and T. pallidum biology could result in novel measures to curtail syphilis spread, including new therapeutics, a preventive vaccine, and, most importantly, improved diagnostics. Methods: Using overlapping synthetic peptides spanning the length of the T. pallidum Tp0435 mature lipoprotein, an abundant antigen known to induce an immunodominant humoral response during both natural and experimental infection, we evaluated which Tp0435 linear epitopes are most significantly recognized by antibodies from an infected host. Specifically, we used sera from 63 patients with syphilis at different stages, sera from non-syphilis patients (n = 40), and sera longitudinally collected from 10 rabbits infected with either the Nichols or SS14 isolates of T. pallidum, which represent the model strains for the two known circulating clades of this pathogen, to further evaluate the use of this animal model for syphilis studies. Recognized amino acid sequences were then mapped to the experimentally determined Tp0435 structure. Results: Reactive epitopes in both serum groups mapped predominantly to the α-helix preceding Tp0435 soluble β-barrel and the loops of the barrel. Conclusions: In the current effort to improve current syphilis diagnostics, the peptides corresponding to these immunodominant epitopes could help develop epitope-based assays such as peptide-based ELISAs and lateral flow point-of-care tests to improve the performance of treponemal tests and expedite diagnosis in low-income settings, where the infection is still a significant concern for public health and access to facilities with laboratories equipped to perform complex procedures might be challenging. Full article

Objectives: CA19-9 elevation in non-gastrointestinal tumor patients may be influenced by various non-tumor factors, which poses challenges for clinical diagnosis. This study aims to assess the consistency between initial elevated CA19-9 levels detected by the ARCHITECT/Alinity i system (Abbott Diagnostics) and subsequent retesting using the Elecsys CA19-9 assay (Roche Diagnostics) in 5372 non-gastrointestinal tumor patients, and to explore potential factors contributing to CA19-9 non-specific elevation. Methods: Bland-Altman and Passing-Bablok analyses were used to assess the agreement between the two assays. Nonparametric Spearman and Pearson’s chi-square tests were used to assess the correlation between CA19-9 and different clinical comorbidities/antigen concentration strata and to compare the categorization by age/disease, respectively. Results: Bland–Altman and Passing–Bablok regression analyses revealed that the CA19-9 test results from Abbott and Roche platforms show significant systematic bias and weak correlation, making the two methods not directly interchangeable. After excluding common confounders, the study focused on heterophilic antibodies (HAs) as target. Blood samples were treated with a commercial blocking agent demonstrated alignment with baseline Elecsys CA19-9 results but differed significantly from initial ARCHITECT/Alinity i measurements. Furthermore, non-specific CA19-9 elevation was also associated with comorbidities such as diabetes mellitus, pulmonary infections, breast nodules, uterine leiomyoma, and its incidence increased with age. Conclusions: The study highlights the need to consider potential interferences and underlying disorders when results conflict with clinical diagnoses. Method-specific validation and comprehensive clinical correlation are crucial for accurate interpretation of CA19-9 levels to prevent misdiagnosis and ensure appropriate patient management. Full article

Background/Objectives: Randomised trials show that screening with prostate-specific antigen (PSA) and systematic prostate biopsies can reduce prostate cancer mortality but leads to high rates of overdiagnosis. Today, improved diagnostic methods more selectively detect potentially lethal, high-grade prostate cancer. Methods: This is a narrative review of modern diagnostic methods, ongoing trials, national policies and knowledge gaps related to screening and early detection of prostate cancer. Results: Screening intervals can be prolonged in men with PSA values below around 1 ng/mL as these men are at very low long-term risk of prostate cancer death. Overdiagnosis can be reduced by magnetic resonance imaging (MRI) and lesion-targeted prostate biopsies. Risk calculators and ancillary biomarkers can select men for further investigation and thereby reduce resource needs. These new methods are evaluated in large, randomised screening trials. The remaining knowledge gaps include optimal PSA cut-offs, screening intervals, start and stop ages, and the long-term balance between benefits and harm. Until recently, almost no national healthcare authority recommended population-based screening for prostate cancer. Now, the European Union Council recommends an evaluation of the feasibility of organised, risk-stratified screening. This has led to several pilot projects. In some other parts of the world, such as sub-Saharan Africa and the Caribbean, such initiatives are lacking despite high prostate cancer mortality rates. Conclusions: Risk-stratified prostate cancer screening including MRI and targeted biopsy reduces overdiagnosis. Results from ongoing research are needed to optimise screening protocols and to define long-term benefits and harms. Initiatives for early detection and screening are emerging across the world but are still lacking in many countries with high prostate cancer mortality. Full article

Laboratory confirmation of human leptospirosis relies on serological tests, with the microscopic agglutination test (MAT) as the reference. However, due to its complexity, there is a need for a simpler and more accessible diagnostic method. This study aimed to standardise and develop an IgM dot-blot test with a whole-cell antigen from saprophytic Leptospira biflexa serovar Patoc for diagnosing human leptospirosis. After checkerboard titration standardisation, IgM dot-blot was performed with paired serum samples from 124 MAT-confirmed leptospirosis cases and 143 serum samples from healthy and diseased individuals as the control group. Repeatability and reproducibility were also evaluated. An IgM dot-blot kit was then developed and compared to the Panbio^TM Leptospira IgM ELISA using 144 serum samples from patients with suspected leptospirosis. The IgM dot-blot showed a sensitivity of 58.1% and 96.0% when performed on acute and convalescent samples, respectively. Specificity was 94.4%. The repeatability and reproducibility of the IgM dot-blot showed 100% consistency. Comparison of IgM dot-blot and IgM ELISA showed almost perfect agreement, with a Kappa index of 0.81. The developed IgM dot-blot offers a robust alternative to existing methods, requiring minimal specialised equipment and fewer reagents than IgM ELISA. The good performance of this IgM dot-blot immunoassay makes it a promising tool for diagnosing human leptospirosis, potentially increasing diagnostic capacity, especially in places with limited resources. Full article

Background/Objectives: Early detection of pancreatic cancer can improve patient survival, and blood-based biomarkers to aid in this are a significant need. The goal of this study was to develop and evaluate the performance of a 4- to 6-plex biomarker signature for detection of early-stage pancreatic ductal adenocarcinoma (PDAC) that performs well in high-risk controls. Methods: Enzyme-linked immunosorbent assays were used to measure 10 previously identified serum protein biomarker candidates in Stage I and II PDAC cases (n = 128), high-risk controls (n = 465), and normal-risk controls (n = 30). Various combinations of biomarker candidates (models) were trained using machine learning and tested for robustness in differentiating cases from controls on the full cohort and in clinically relevant sub-types including those with diabetes, those ≥65 years of age, and low producers of carbohydrate antigen 19-9 (CA 19-9). Results: At 98% specificity, the top performing model, which was comprised of tissue inhibitor of metalloproteinase 1 (TIMP1), intracellular adhesion molecule 1 (ICAM1), thrombospondin 1 (THBS1), cathepsin D (CTSD), and CA 19-9, achieved 85% sensitivity in the full cohort and sensitivities of 91% in diabetics, 90% in ≥65 years of age, and 60% in low CA 19-9 producers. This model demonstrated significantly higher sensitivity in detecting PDAC in the full cohort and all sub-populations compared to CA 19-9 alone (p < 0.001). Conclusions: Our findings demonstrate the feasibility of a blood-based assay for detecting early-stage PDAC in high-risk individuals and key sub-populations, representing an important step towards improving diagnostic success for early-stage disease. Full article

Background/Objectives: The COVID-19 pandemic, caused by SARS-CoV-2, required the rapid development of diagnostic tests. SARS-CoV-2, part of the betacoronavirus genus, shares characteristics with SARS-CoV-1, including its ability to survive on surfaces, facilitating the spread of the infection. This study analyzes the technique of nasopharyngeal secretion collection for SARS-CoV-2 diagnosis and compares the accuracy of rapid antigen and molecular tests. Methods: This study had two components: study A assessed the healthcare personnel training in collecting nasopharyngeal secretions and the discomfort associated with applying a questionnaire. Study B compared rapid antigen test accuracy with RT-PCR among children, through a retrospective analysis. The data were statistically analyzed to assess compliance with the testing protocols. Results: In study A, 88 healthcare workers achieved an average compliance score of 7.60 out of 10 regarding the collection procedure. Over 70% of participants correctly followed the fundamental steps of the procedure. Many patients who underwent sample collection reported pain and symptoms such as coughing or sneezing. In study B, 198 pediatric patients were tested using rapid antigen tests, collected simultaneously with RT-PCR. The rapid tests showed a 50% sensitivity and 97.5% specificity. Conclusions: This study indicates that nasopharyngeal specimen collection techniques are based on international recommendations, but improvements could be made to reduce discomfort. Rapid antigen tests are helpful for screening due to their high specificity and negative predictive value. Continuous healthcare personnel training and the monitoring of diagnostic techniques remain essential in managing SARS-CoV-2 and other viral infections. Full article

In this report, we document and analyze a case in which the Irkut virus (IRKV) (Mononegavirales: Rhabdoviridae) caused a fatal human case following a bat bite in June 2021. Unfortunately, the available data did not permit a detailed taxonomic classification of the carrier bat (Chiroptera). The event occurred in the southwestern part of the Sikhote-Alin mountain region (Russian Far East) covered by the Ussuri taiga forest. The symptoms of the illness began with the following: fever; pronounced psychomotor and motor agitation; tremor of the lower jaw and tongue; aphasia; dyslexia; and dysphagia. These rapidly developed, leading to a severe and fatal encephalitis. The patient was not vaccinated for rabies and did not receive rabies immunoglobulin. Using brain sections prepared from the deceased, molecular diagnostics were performed: immunofluorescence (polyclonal anti-rabies immunoglobulin) indicating the presence of the lyssavirus antigen; and RT-PCR indicating traces of viral RNA. Sectional material (brain) was used for whole-genome sequencing, resulting in a near-complete sequence of the lyssavirus genome. The obtained genomic sequence was identified as the Irkut virus. A comparative analysis of the new sequence and other currently available IRKV sequences (NCBI) revealed differences. Specifically, amino acid differences between antigenic sites in the isolate and those of the rabies vaccine strain used regionally were noted. The patient history and subsequent analysis confirm human IRKV infection following bat contact. Like other fatal cases of IRKV infection described earlier, this case occurred in the southern part of the Russian Far East. Two have occurred in the southwestern part of the Sikhote-Alin mountain region. This indicates the possible existence of an active, natural viral focus. Full article

B Cell Maturation Antigen (BCMA) has gained considerable attention as a target in directed therapies for multiple myeloma (MM) treatment, via immunoglobulin-based bispecific T cell engagers or CAR T cell strategies. We describe the development of alternative, non-immunoglobulin BCMA-recognising affinity proteins, based on the small (58 aa) three-helix bundle affibody scaffold. A first selection campaign using a naïve affibody phage library resulted in the isolation of several BCMA-binding clones with different kinetic profiles. One clone showing the slowest dissociation kinetics was chosen as the template for the construction of two second-generation libraries. Characterization of output clones from selections using these libraries led to the identification of clone 1-E6, which demonstrated low nM affinity to BCMA and high thermal stability. Biosensor experiments showed that 1-E6 interfered with the binding of BCMA to both its natural ligand APRIL and to the clinically evaluated anti-BCMA monoclonal antibody belantamab, suggesting overlapping epitopes. A fluorescently labelled head-to-tail homodimer construct of 1-E6 showed specific binding to the BCMA⁺ MM.1s cell line in both flow cytometry and fluorescence microscopy. Taken together, the results suggest that the small anti-BCMA affibody 1-E6 could be an interesting alternative to antibody-based affinity units in the development of BCMA-targeted therapies and diagnostics. Full article

Influenza poses a significant global health burden due to its high transmissibility, antigenic variability, and substantial morbidity. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has further complicated influenza dynamics, highlighting the need for rapid, accurate, and accessible diagnostics. This review comprehensively summarized the advancements in influenza virus (IFV) detection, from conventional methods like viral culture and serology to modern molecular techniques, including CRISPR-based systems, next-generation sequencing (NGS), and biosensors. We analyze the sensitivity, specificity, and applicability of these methods and emphasize their roles in clinical and public health settings. While traditional techniques remain valuable for strain characterization, novel technologies like CRISPR and portable biosensors offer rapid, low-resource solutions. This review provides a comprehensive insight into the development of integrated diagnostic strategies for seasonal IFV epidemics and future pandemics. Full article

Cases of new COVID-19 infection, which manifested in 2019 and caused a global socioeconomic crisis, still continue to be registered worldwide. The high mutational activity of SARS-CoV-2 leads to the emergence of new antigenic variants of the virus, which significantly reduces the effectiveness of COVID-19 vaccines, as well as the sensitivity of diagnostic test systems based on variable viral antigens. These problems may be solved by focusing on highly conserved coronavirus antigens, for example nucleocapsid (N) protein, which is actively expressed by coronavirus-infected cells and serves as a target for the production of virus-specific antibodies and T cell responses. It is known that anti-N antibodies are non-neutralizing, but their protective potential and functional activity are not sufficiently studied. Here, the protective effect of anti-N antibodies was studied in Syrian hamsters passively immunized with polyclonal sera raised to N(B.1) recombinant protein. The animals were infected with 10⁵ or 10⁴ TCID₅₀ of SARS-CoV-2 (B.1, Wuhan or BA.2.86.1.1.18, Omicron) 6 h after serum passive transfer, and protection was assessed by weight loss, clinical manifestation of disease, viral titers in the respiratory tract, as well as by the histopathological evaluation of lung tissues. The functional activity of anti-N(B.1) antibodies was evaluated by complement-dependent cytotoxicity (CDC) and antibody-dependent cytotoxicity (ADCC) assays. The protection of anti-N antibodies was evident only against a lower dose of SARS-CoV-2 (B.1) challenge, whereas almost no protection was revealed against BA.2.86.1.1.18 variant. Anti-N(B.1) monoclonal antibodies were able to stimulate both CDC and ADCC. Thus, anti-N(B.1) antibodies possess protective activity against homologous challenge infection, which is possibly mediated by innate Fc-mediated immune reactions. These data may be informative for the development of N-based broadly protective COVID-19 vaccines. Full article

Foot-and-mouth disease (FMD) is a devastating infectious viral disease of cloven-hoofed animals. Differentiating FMD from other vesicular diseases is difficult based on only clinical symptoms, requiring an appropriate laboratory diagnostic test. The double-antibody sandwich (DAS)-ELISA is a reliable diagnostic technique for antigen detection and serotyping of FMDV. However, classical DAS-ELISAs use polyclonal antibodies (pAbs), which are inconsistent in yields and limited in large-scale applications compared to hybridoma cell-secreted laboratory-made monoclonal antibodies (mAbs). Therefore, this study aimed to develop simplified and sensitive FMD serotype-specific DAS-ELISAs using HRP-conjugated mAbs and a TMB substrate. Six FMDV serotype-specific mAb-DAS-ELISAs were developed. All assays were optimized using BEI-inactivated FMD antigens. Real-time reverse-transcriptase PCR (RRT-PCR) was also used to verify the detection efficiency of all assays. Known negative and positive 10% tissue suspensions of different animal origins were examined to calculate the diagnostic specificity (DSp) and sensitivity (DSe). Serotype-specific mAb-DAS-ELISAs demonstrated 100%, 97%, 97%, 99%, 99%, and 94% DSp and 100%, 95%, 90%, 95%, 100%, and 100% DSe for serotypes O, A, Asia-1, SAT-1, SAT-2, and SAT-3, respectively. The detection efficiency of mAb-DAS-ELISAs was better than that of classical DAS-ELISAs. Also, all assays demonstrated minimal cross-reactivity and optimal reproducibility. Therefore, the mAb-DAS-ELISAs developed in this study could be useful for detecting and serotyping FMDV and ultimately replacing the classical DAS-ELISA. Full article

Background: The role and underlying mechanisms of synaptophysin-like-1 (SYPL1), a neuroendocrine-associated protein, in pancreatic ductal adenocarcinoma (PDAC) remain unclear. This study aims to assess the diagnostic potential of SYPL1 as a serum biomarker for both resectable PDAC (rPDAC) and metastatic PDAC (mPDAC) located at the head of the pancreas. Additionally, the SYPL1 levels were monitored in PDAC patients who underwent surgical resection, with follow-up measurements taken 6 months postoperatively. Method: We analyzed serum SYPL1 in healthy controls (n = 67), rPDAC patients (n = 39), mPDAC patients (n = 22), and rPDAC patients (6-month postoperative) (n = 20) (due to factors such as relocation or death, 20 patients were included instead of 39 patients) by ELISA. Results: The SYPL-1 levels showed significant differences across the groups (controls: 7.43 ± 3.32, PC: 15.89 ± 2.00, mPDAC: 20.01 ± 4.03, p < 0.001). Both carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were significantly greater in cancer groups compared to the healthy group. In patients who underwent surgical resection, the SYPL-1 levels showed a significant decrease 6 months after surgery (p < 0.001). Strong correlations were observed between tumor markers, with CA19-9 showing a positive correlation with CEA in both rPDAC (r = 0.550, p < 0.001) and mPDAC (r = 0.623, p = 0.002), while SYPL-1 demonstrated a negative correlation with CEA (r = −0.530, p = 0.009) in mPDAC. Receiver operating characteristic (ROC) analysis revealed excellent diagnostic performance for SYPL-1 in distinguishing both rPDAC (AUC = 0.965) and mPDAC (AUC = 0.985) from healthy controls, achieving superior accuracy compared to conventional markers CEA and CA19-9. Conclusions: Serum SYPL-1 emerges as a promising biomarker for the diagnosis and monitoring of rPDAC and mPDAC. Its significantly elevated levels in cancer groups, coupled with its marked decrease following surgical resection, suggest that SYPL-1 could play a critical role in both initial diagnosis and post-treatment surveillance. The strong correlations observed between SYPL-1, CEA, and CA19-9 further support its potential utility in a multi-marker panel. Notably, SYPL-1 demonstrated superior diagnostic accuracy compared to conventional markers, with high AUC values indicating its excellent ability to distinguish rPDAC and mPDAC from healthy controls. These findings highlight the need for further investigation to validate SYPL-1 as a reliable, non-invasive biomarker that could enhance early detection, prognosis, and treatment monitoring in rPDAC. Full article

This study investigated the IgA antibodies targeting bovine serum albumin (BSA) in 27 adult celiac disease (CD) patients adhering to a gluten-free diet (GFD), compared to 123 controls (including individuals with autoimmune disorders, those with gastrointestinal cancers, and healthy donors). Serum samples were evaluated using a multiplex assay based on a microarray comprising 66 immobilized antigens, including autoantigens associated with autoimmune diseases, different albumins, cytokines, and inflammatory markers. Elevated IgA-BSA levels were detected in 22% of CD patients versus 3.25% of controls. IgA-BSA did not cross-react with milk proteins like casein, β-lactoglobulin, and γ-globulin, nor with autoantigens and human albumin, ruling out autoimmunity against self-proteins. The observed cross-reactivity with porcine albumin suggests that antibodies target epitopes shared by bovine and porcine albumin. Increased IgA-BSA levels may interfere with immunoassays performed using BSA as a stabilizer, necessitating protein-free buffers to avoid false results when testing CD patients. Elevated IgA-BSA levels may reflect ongoing gut barrier dysfunction in CD patients on a GFD, allowing dietary proteins like BSA to trigger immune responses. This study identifies a novel immune response in CD patients on a GFD, emphasizing the need for tailored diagnostic approaches (BSA-free assays) and further research into the clinical and dietary implications of IgA-BSA elevation. Full article

Toxoplasma gondii is a globally significant zoonotic pathogen responsible for severe parasitic diseases in humans and animals. This study aimed to design, develop, and evaluate a novel immunochromatographic test (ICT) using a recombinant MIC2-MIC3 fusion protein (rMIC2-MIC3) for detecting specific antibodies against T. gondii. The ICT demonstrated exceptional sensitivity, capable of detecting T. gondii-specific antibodies in sera diluted up to 1:8. Specificity evaluation confirmed no cross-reactivity with antibodies against other parasites, such as Neospora caninum, Cryptosporidium suis, Eimeria tenella, and Sarcocystis tenella. Stability tests revealed the test strips maintained full functionality after 12 weeks of storage at 24 °C. The coincidence rate of the colloidal gold test strips prepared in this study with a commercial ELISA kit was 94.59%. Comparisons with advanced serodiagnostic tools, such as chimeric antigen-based ELISAs and recombinant protein diagnostics, further highlighted its robustness and applicability. These findings underscore the potential of the rMIC2-MIC3-based ICT as a reliable, economical, and accessible diagnostic tool for toxoplasmosis in veterinary and human medicine. Full article

Accurate dating of Toxoplasma gondii infection is essential for effective clinical management, particularly in pregnant women and immunocompromised individuals, where distinguishing acute from chronic infection informs treatment decisions. Serological detection of IgM antibodies is a key tool in diagnosing recent toxoplasmosis; however, its reliability is compromised by persistent IgM responses, cross-reactivity, and assay variability. While IgM lacks sufficient specificity to serve as a standalone marker of acute infection, it remains an important component of serological panels. This review summarizes current IgM detection methods and explores advancements aimed at improving diagnostic accuracy with a focus on recombinant antigens, which have emerged as promising alternatives to traditional Toxoplasma lysate antigen-based immunoassays. This paper also explores alternative methods of differentiating chronic and acute toxoplasmosis and outlines key areas for future research. Full article