Specific Antibodies Research Articles

The protective effect of specific yolk antibody against Nervous necrosis virus infection in Mandarin fish(Siniperca chuatsi)

Nervous necrosis virus (NNV), a member of the Nodavirus genus, is a highly contagious disease that is found all over the world. As of right now, there aren't many reliable commercial vaccines available to combat this infection. In a previous study, we isolated a Mandarin fish (Siniperca chuatsi)-derived NNV strain, tentatively named MFNNV. By immunizing hens with MFNNV recombinant capsid protein (CP), this study produced high-purity anti-MFNNV yolk antibodies. According to the ELISA results, the purified anti-MFNNV IgY titer peaked at week 8 after the first vaccination; western blotting and indirect immunofluorescence results showed that IgY could act as a primary antibody to specifically recognize recombinant CP and virus particles. At the cellular level, specific IgY significantly reduced the appearance of vacuolated cytopathic effect in GS cells after incubation with an equal volume of virus compared with non-specific IgY. Mandarin fish was fed diets supplemented with anti-MFNNV IgY or non-specific IgY at 33% (w/w) for 7 days prior to artificial infection with MFNNV. On the 14th day of artificial infection with MFNNV, the mortality rate was 53.3% in the specific group and 83.3% in the nonspecific group, and the relative protection rate of the specific IgY group was about 36% compared with that of the nonspecific IgY group. In histopathological analysis, vacuolizing lesions were observed in the brain tissues of Mandarin fish in the non-specific group, whereas only slight vacuolization was observed in the brain tissues of the specific group. Further analysis revealed that compared with the non-specific group, the MFNNV-CP gene expression in the eyes as well as the brain of Mandarin fish in the specific group showed a significant decrease, and the mRNA expression levels of immune-related factors, such as TNF-α, IFN-h, IL-1, IL-8, Mx proteins, and IgM in the spleen, liver, kidney, and hindgut tissues of the specific group also showed a decrease of varying degrees, suggesting that oral administration of specific IgY could neutralize virus and reduce the immune responses as well as tissue pathological damage induced by the Nervous necrosis virus. Consequently, we suggested that IgY could protect Mandarin fish from MFNNV infection by acting as a passive immunological measure.

Antibody selection and automated quantification of TRPV1 immunofluorescence on human skin

AbstractAssessing localization of the transient receptor potential vanilloid-1 (TRPV1) in skin nerve fibers is crucial for understanding its role in peripheral neuropathy and pain. However, information on the specificity and sensitivity of TRPV1 antibodies used for immunofluorescence (IF) on human skin is currently lacking. To find a reliable TRPV1 antibody and IF protocol, we explored antibody candidates from different manufacturers, used rat DRG sections and human skin samples for screening and human TRPV1-expressing HEK293 cells for further validation. Final specificity assessment was done on human skin samples. Additionally, we developed two automated image analysis methods: a Python-based deep-learning approach and a Fiji-based machine-learning approach. These methods involve training a model or classifier for nerve fibers based on pre-annotations and utilize a nerve fiber mask to filter and count TRPV1 immunoreactive puncta and TRPV1 fluorescence intensity on nerve fibers. Both automated analysis methods effectively distinguished TRPV1 signals on nerve fibers from those in keratinocytes, demonstrating high reliability as evidenced by excellent intraclass correlation coefficient (ICC) values exceeding 0.75. This method holds the potential to uncover alterations in TRPV1 associated with neuropathic pain conditions, using a minimally invasive approach.

Performance Assessment of ELISA Using the Trypanosoma cruzi-Specific Antigen Tc323 for the Diagnosis of Chronic Chagas Disease.

In the chronic phase of Chagas disease (CCD), diagnosis relies on detecting specific IgG antibodies due to the low or absent presence of the parasiteTrypanosoma cruzi in human blood. However, the performance of current serological tests is highly variable, lacking a "gold standard" assay with 100% sensitivity and specificity, which challenges the exploration of new biomarkers. In the present study, we evaluated the diagnostic accuracy of an optimized ELISA using the predicted immunogenic domains (called TcD3 and TcD6) of Tc323, a protein highly conserved among T.cruzi strains but absent in other clinically significant parasites such as Leishmania spp. This study was conducted using plasma or serum samples from CCD individuals with different clinical manifestations and living in endemic regions in Latin America, subjects with unrelated infectious diseases, and noninfected donors. The sensitivity and specificity of recombinant TcD3 were 90.8% and 92.6%, respectively, while rTcD6 displayed values of 93.1% and 93.6% for the same parameters. Area under curve (AUC) values were 0.949 for rTcD3 and 0.954 for rTcD6. The receiver operative characteristic (ROC) curve showed a highly significant difference between CCD individuals and noninfected donors. Cross-reactivity was 10.2% for rTcD3 and 8.2% for rTcD6 in subjects infected with leishmaniasis or with toxoplasmosis. In addition, the reactivity against rTcD3 differed among some geographical areas while no significant difference was found using both domains for the detection of T.cruzi-infected individuals with or without cardiac symptoms. Our findings show that the recombinant antigens rTcD3 and rTcD6 could be used as highly potential biomarkers for the serological diagnosis of CCD.

Real-world application of disitamab vedotin (RC48-ADC) in patients withbreast cancer with different HER2 expression levels: efficacy and safety analysis.

Disitamab vedotin (RC48-ADC), an antibody-drug conjugate (ADC), combines specific antibody disitamab with cytotoxicity monomethyl auristatin E to effectively target the human epidermal growth factor receptor 2 (HER2) protein on tumor cells for precise elimination. Recent studies have demonstrated that RC48-ADC offers therapeutic benefits for patients with HER2-positive and HER2-low-expression breast cancer (BC). However, a thorough exploration of its efficacy and safety in real-world settings for patients with metastatic breast cancer (mBC) is currently lacking. This retrospective, multicenter, real-world study included patients with mBC who received RC48-ADC from September 2021 to March 2024. These patients include HER2-positive BC and HER2-low-expression BC. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), restricted mean survival time, objective response rate (ORR), and disease control rate (DCR). Factors affecting efficacy and the occurrence of treatment-related adverse events (TRAE) were evaluated. The study included a cohort of 89 patients with mBC, with 48 of those being identified as HER2-positive. As of March 2024, 22 deaths were recorded, with an immature median OS. Total PFS varied from 1.0 to 31.2 months, with a median of 5.5 months (95% CI, 4.368-6.632). HER2-positive patients exhibited prolonged PFS compared with HER2-low-expression patients (6.6 months vs 4.1 months, P = .023). The overall ORR stood at 25.8% (95% CI, 0.178-0.358), with higher rates observed in HER2-positive patients compared with HER2-low-expression patients (31.3% vs 19.5%). Similarly, the overall DCR was 78.7% (95% CI, 0.691-0.859), with HER2-positive patients demonstrating superior DCR compared with HER2-low-expression patients (83.3% vs 73.2%). Notably, HER2 expression emerged as the primary determinant of RC48-ADC efficacy. The most prevalent TRAE among all patients included leukopenia (21.3%) and alopecia (20.2%). RC48-ADC showcases promising efficacy and manageable safety in patients with both HER2-positive and HER2-low-expression mBC.

Protective threshold of a potent neutralizing Zika virus monoclonal antibody in rhesus macaques.

Zika virus (ZIKV) is a mosquito-borne flavivirus that caused a global pandemic in 2016-2017 with continued ongoing transmission at low levels in several countries. In the absence of an approved ZIKV vaccine, neutralizing monoclonal antibodies (mAbs) provide an option for the prevention and treatment of ZIKV infection. Previous studies identified a potent neutralizing human mAb ZIKV-117 that reduced fetal infection and death in mice following ZIKV challenge. In this study, we report exquisite potency of ZIKV-117-LALA-YTE, which has been engineered to reduce Fc receptor binding and to extend half-life, in a titration study in rhesus macaques to protect against ZIKV challenge. We show complete protection at a dose of 0.016 mg/kg ZIKV-117-LALA-YTE, which resulted in median serum concentrations of 0.13 µg/mL. The high potency of this mAb supports its potential clinical development as a novel biotherapeutic intervention for ZIKV.IMPORTANCEIn this study, we report the potency of the Zika virus (ZIKV)-specific neutralizing antibody ZIKV-117-LALA-YTE against ZIKV challenge in a titration study rhesus macaques. This high potency supports the further development of this monoclonal antibody for ZIKV.

Abstract A024: Assessing Mitondiral Priming in Leukemia Using BH3 Complex Specific Antibodies (PRIMABS): Prediciting Patient Response to Apoptosis Inducing Drugs

Abstract Diagnostic tools for cancer therapy that enable oncologists to inform patients about the likely benefits of their treatment versus toxicity will empower patients to make evidence-based decisions about the management of their disease, and in some cases, their last phase of life. Here we provide a novel approach that measures key drug response features of individual cancer cells with the potential for providing prognostic/predictive diagnostic utility for practicing precision medicine. Most cancer treatments work though activation of the cell suicide program of apoptosis. This process is tightly regulated by the BCL-2 family of proteins whose members either prevent or promote cell death. The relative levels of, and the specific interactions between the pro-survival and pro-apoptotic family members that dictates the fate of all cells and determines their propensity to undergo apoptosis. Cells that more readily die in response to various stimuli are referred to as “primed”. Hence, the degree of priming of a tumor sample can be predictive of responses to anti-cancer drugs and can be established using a technique called “BH3 profiling”. The relevance of this method has been demonstrated but it has had only limited application. To address this limitation a unique panel of antibody-based reagents that are mitochondrial PRIMing state detecting Antibodies (PRIMABS), have been developed by our lab, as a novel approach to implementing personalized medicine and developing predicative diagnostic tests. These antibodies enable the degree of tumor cell priming to be determined directly, unlike BH3 profiling which is an indirect measure. The key innovation lies in the approach taken to determine the presence (or absence) of the critical pro-survival : pro-apoptotic protein complexes , as these are the principal determinants of cell priming.. Such PRIMAB reagents have hitherto not been available. Here we provide data outlining the methodology development as well as evidence demonstrating feasibility of PRIMABTM Dx platform for predicting AML and CLL patient response in retrospective studies. Our platform provides a PD biomarker that will become a clinical predictor of cancer cell response to treatments tat are intended to induce apopstosis in tumor cells. The PRIMABTM -DX platform will enable heretofore hard to achieve clinical applicability of priming measurements. This will be significant due to the important prognostic implications of PRIMAB-DxTM readouts and will provide insights into drug resistance and sensitivity mechanisms and lead to new treatment options for cancer patients. Citation Format: Michael Cardone. Assessing Mitondiral Priming in Leukemia Using BH3 Complex Specific Antibodies (PRIMABS): Prediciting Patient Response to Apoptosis Inducing Drugs [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr A024.

A subunit vaccine based on P97R1, P46, P42, and P65 from Mycoplasma hyopneumoniae can induce significant immune response in piglets

Mycoplasma pneumonia (MPS), caused by Mycoplasma hyopneumoniae (Mhp), is a chronic, airborne respiratory disease that poses a significant threat to the global swine industry. The P97 and P46 proteins are major antigens of Mhp, with the R1 region of P97 possessing full adhesive capability. Studies have shown that the main antigenic regions of Mhp P42 and P65 proteins exhibit strong immunogenicity. In this study, we first linked the genes encoding P97R1 and P46 proteins to form the P97R1P65 gene and subsequently constructed three shuttle plasmids: pFBD-P97R1P46, pFBD-P97R1P46-p65, and pFBD-P65-P42. These proteins were expressed using the Bac to Bac system and formulated into subunit vaccines for mouse immunization. Mouse experiments indicated that the P97R1P46 + P65-P42 protein combination elicited higher levels of specific antibodies, IL-2, IL-4, and CD8+ T cells compared to other subunit vaccine groups, a finding further validated in subsequent mouse challenge protection experiments. Therefore, we utilized the MultiBac expression system to co-express P97R1P46, P65, and P42 proteins in the pFastMultibacDual vector for immunization experiments in piglets. The piglet immunization experiments demonstrated that the Mhp subunit vaccine prepared in this study could induce specific antibodies against Mhp, with the combination of P97R1P46, P65, and P42 proteins inducing the highest level of humoral immunity. This study provides valuable insights for the development of Mhp subunit vaccines.

Antibody–Drug Conjugates: A Start of a New Era in Gynecological Cancers

Antibody–drug conjugates (ADCs) are a new class of therapeutic agents designed to target specific antigens on tumor cells, combining the specificity of monoclonal antibodies with the cytotoxicity of chemotherapy agents. ADCs have been available for over a decade, but in gynecological cancers, these agents are relatively new with great promise ahead. More than 80% of ongoing trials in gynecological cancers are evaluating ADCs’ safety and efficacy, of which 40% are early-phase trials. Around twenty ADCs are currently under investigation, either alone or in combination with chemotherapies or immune checkpoint inhibitors. Among them, mirvetuximab soravtansine has been recently approved by the Food and Drug Administration (FDA) in platinum-resistant ovarian cancer with high folate-α receptor expression, as a single agent or in combination. Tisotumab vedotin and trastuzumab deruxtecan are also now approved by the FDA in patients with pre-treated cervical and uterine cancers and further investigation is ongoing. Overall, the toxicity profiles of ADCs are acceptable. Ocular toxicity is one of the specific side effects of some ADCs, but most of the cases are manageable with the use of prophylactic steroids and dose adjustments. This review aims to provide an overview of the fundamental and operational features of ADCs and examine the latest and most promising data, with a particular focus on the Canadian viewpoint.

Analysis of allergen positivity rates in relation to gender, age, and cross-reactivity patterns.

This study aims to gain a deeper understanding of the patterns of allergen detection positivity rates among different age and gender groups, and to explore cross-reactivity patterns among allergens. We conducted a retrospective analysis of patients who underwent allergen testing at our hospital. The sample for this study included all patients who underwent allergen testing. We utilized immune blotting to detect specific IgE antibodies to 20 allergens in patient sera. The study results showed a higher proportion of female samples (72.35%) compared to male samples (27.65%). Among all participants, the age distribution was primarily concentrated in the 25-35 age group, accounting for 37.43% of the total sample, followed by the 45 years and older age group, accounting for 27.00%. This indicates that allergic symptoms may occur not only in children and adolescents but also at any time after adulthood. We further observed significant influences of factors such as gender and age on individual sensitivity to specific allergens. For example, compared to males, females were found to be more sensitive to certain allergens such as cat hair, dust mites, and dog epithelium. Similarly, we also found variations in sensitivity to specific allergens among different age groups. Close monitoring of allergen distribution in populations facilitates active engagement of allergic individuals in self-management, while gender and age may be important factors influencing individual sensitivity to specific allergens. These findings provide valuable insights for understanding the pathogenesis of allergic diseases and designing more effective prevention and treatment strategies.

Abstract A059: Serum EphA2 proteolytic fragment is a potent biomarker for diagnosing a very early stage of ductal pancreatic carcinoma

Abstract Erythropoietin-producing hepatocellular receptor A2 (EphA2) is a receptor tyrosine kinase, and its expression increases with malignant progression of cancer. Therefore, EphA2 is believed to be a candidate for molecular cancer therapy and many candidate drugs targeting EphA2 have been developed, but their effects are limited. The reason is its complex signaling functions. In fact, EphA2 has a tumor suppressor function regulated by the stimulation of the Ephrin-A ligand, while in the absence of ligand stimulation, it has a prooncogenic function in collaboration with EGFR and its downstream signaling molecules. The opposite functions of EphA2 make it difficult to develop it as a cancer drug target. We have previously demonstrated that a type-1 matrix membrane metalloprotease (MT1-MMP) at cancer cell surface interacted with EphA2 and selectively cleaved its N-terminal ligand binding site, converting it into a prooncogenic signaling transmitter (Koshikawa N et al., Cancer Research, 2015). We also found that the N- terminal fragment of EphA2 (termed EphA2-NF) released by MT1-MMP cleavage increased in sera from patients with gastric cancer and ductal pancreatic carcinoma (PDC) (Koshikawa N et al., Cell Death & Disease, 2017). In this study, we compare the expression of EphA2-NF in serum from a healthy donor (HD: 150 cases), patients with chronic pancreatic disease (87 cases), and PDC (578 cases) by automated chemiluminescence immunoassay with a specific EphA2-NF monoclonal antibody. As a result, PDC cases, including stage I/II PDC, show significantly higher levels of EphA2-NF than HD (Sato et al. Cancer Research Communications, 2023). Furthermore, PDC occurred in the intraductal papillary mucinous neoplasm (IPMN) cases with high levels of EphA2-NF during follow-up observation. Therefore, to verify that the EphA2 proteolytic cleavage occurred in the PDC onset, we analyzed 50 surgical resected tissues from patients with PDC and IPMN to detect the N and C-terminal regions of EphA2 by immunohistochemical staining. Interestingly, PDC, including early stage PDC cases, lacked the N-terminus of EphA2. Furthermore, the deletion of N-terminus of EphA2 was observed in all tested cases pathologically diagnosed as intraductal papillary mucinous adenocarcinoma (IPMC) (Sato S et al., Cancer Research Communications, 2023). These results suggest that serum EphA2-NF has the potential to revolutionize the early detection and management of PDC, providing a valuable tool to diagnose the disease in very early stages when treatment results may be more favorable. Collaborators: Masatoshi Nakagawa, Eisaku Yoshida and Toru Yoshimura (Research and Development, Abbott Japan LLC) Citation Format: Naohiko Koshikawa, Shinya Sato, Kouki Nio, Takeshi Terashima, Makoto Ueno, Taro Yamashita. Serum EphA2 proteolytic fragment is a potent biomarker for diagnosing a very early stage of ductal pancreatic carcinoma [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A059.

Dynamic maternal synthesis and segregation of the germ plasm organizer, Bucky ball, in chicken oocytes and follicles.

Maternal germ plasm determines the germline in birds. Previously, we proposed the chicken-specific Bucky ball (cBuc) as a functional equivalent of the zebrafish germ plasm organizer. This study demonstrated the maternal cBuc synthesis, and verified a highly dynamic distribution of Bucky ball from oocyte nests to maturing follicles using specific antibodies. The dynamic re-localization of cBuc from the ovarian stroma to the granulosa cells, and the Balbiani structure of the oocyte was revealed. Following the accumulation of cBuc in the Balbiani body, an increased signal of chicken vasa homolog (CVH) in close contact to cBuc could be detected. Highest transcription of cBuc was recorded in follicles with diameters up to 500µm. First RNA-interference experiments in an in-vivo follicle culture assay revealed inhibiting effects on cBuc in small follicles. These data demonstrate the maternal origin of cBuc, and underpin its role as germ plasm organizer.

Nanoparticle containing recombinant excretory/secretory-24 protein of Haemonchus contortus enhanced the cellular immune responses in mice

Haemonchus contortus poses a global challenge as a parasite affecting small ruminants, yet the problem of absence of an effective vaccine against H. contortus infection still exists. This investigation sought to appraise the immunological reaction induced by recombinant H. contortus excretory/secretory-24 (rHcES-24) in combination with complete Freund’s adjuvant (CFA) and bio-polymeric nanoparticles (NPs) within a murine model. In this study, rHcES-24 was encapsulated in poly(d, l-lactide-co-glycolide) (PLGA) and chitosan (CS) NPs, administered subcutaneously to mice. Researchers analyzed the NPs using scanning electron microscope (SEM) and assessed lymphocyte proliferation, specific antibodies, cytokines, T cell proliferation (CD3e+CD4+, CD3e+CD8a+), and phenotypic alteration in splenocytes (CD11c+CD83+, CD11c+CD86+) through flow cytometry to understand the immune response. The results demonstrated that the administration of nanovaccines (NVs) prompted immune responses towards Th1 pathway. This was indicated by notable enhancements in the production of specific antibodies, heightened cytokine levels, and a robust proliferation of lymphocytes observed in mice that received the NVs compared to control groups. Remarkably, mice vaccinated with the antigen-loaded NPs formulations exhibited considerably higher proportions of splenic dendritic cells (DCs) and T cells in comparison to those receiving the traditional adjuvant or the control groups. Incorporating HcES-24 protein into NPs effectively conferred immunity against H. contortus, paving the way for developing a targeted and commercial vaccine.

Oral Bacillus subtilis spores-based vaccine for mass vaccination against porcine reproductive and respiratory syndrome.

Porcine reproductive and respiratory syndrome (PRRS) poses a significant challenge in the global swine industry, leading to substantial economic losses and reproductive and respiratory complications. The causative agent, PRRS virus (PRRSV), with its high mutation rate, complicates the development of universally effective vaccines. Furthermore, current PRRS vaccines are limited by high costs and complex administration methods. Therefore, in this study, we aimed to develop an innovative Bacillus subtilis spore-based oral vaccine targeting PRRS. Their oral administration was evaluated in mice and pigs, and blood, saliva, feces, and bronchoalveolar lavage fluid samples were collected for further analyses. Our vaccine induced IgG and IgA immune responses in both models, with swine demonstrating considerable increase in specific antibody and cytokine levels. These results indicate a high potential for more effective and economically viable control of PRRS in commercial pig farming. The ease of administration and cost-effectiveness of the vaccine also offer a feasible option for widespread application. Our results suggest a new direction in veterinary vaccine development, underscoring the potential of B. subtilis spores in creating effective vaccines for large-scale, real-world applications in animal health management.

Primary Biliary Cholangitis: Personalizing Second-Line Therapies-R1

Primary biliary cholangitis (PBC) is an enigmatic, autoimmune disease targeting the small intralobular bile ducts resulting in cholestasis and potentially progression to biliary cirrhosis. Primarily affecting middle-aged women, the diagnosis of PBC is typically straightforward with most patients presenting with cholestatic liver tests and the highly specific anti-mitochondrial antibody. For decades, the foundational treatment of PBC has been ursodeoxycholic acid (UDCA) which delays disease progression in most patients but has no impact on PBC symptoms. Large cohort studies of patients with PBC have established the benefit of maximizing the reduction in serum alkaline phosphatase with UDCA and the need to add second-line agents in patients who do not achieve an adequate response. Advances in the understanding of bile acid physiology have led to the development of new agents that improve cholestasis in patients with PBC and are predicted to reduce the risk of disease progression. Obeticholic acid, the first second-line therapy to be approved for PBC, significantly improves liver biochemistries and has been associated with improved long term clinical outcomes but is limited by its propensity to induce pruritus. Elafibranor and seladelpar are peroxisome proliferator-activated receptor agonists recently approved for use in patient with PBC, whereas bezafibrate and fenofibrate are available as off-label therapies. They also have shown biochemical improvements among patients with an inadequate response to UDCA, but may improve symptoms of pruritus. Herein, we review the patient features to consider when deciding whether a second-line agent is indicated and which agent to consider for a truly personalized approach to PBC patient care.

Inserting Omp22 into the flagellin protein, replacing its hypervariable region, results in stronger protection against lethal Acinetobacter baumannii infection.

Acinetobacter baumannii, a common nosocomial pathogen, is known for its rapid acquisition of antimicrobial resistance, underscoring the urgent need to develop an effective vaccine against this pathogen. Outer membrane protein 22 (Omp22) regulates the biogenesis of outer membrane vesicles to transport virulence-promoting factors into the host cells and facilitates the progression of A. baumannii infection. In this study, we used a mouse model to assess a vaccine's immunogenicity and protective efficacy using recombinant Omp22 protein within the hypervariable region of flagellin (FliC-Omp22). FliC-Omp22 demonstrated superior protection following challenge with a lethal dose of multidrug-resistant (MDR) A. baumannii strain 58ST compared to Omp22 alone. In addition, it elicited increased IgG1/IgG2a and IL-4/IFN-γ ratios, indicating a predominant Th2 immune response. Furthermore, the FliC-Omp22 vaccination elicited strong specific antibodies that inhibited the adhesion and invasion of A. baumannii 58ST and enhanced the opsonic killing activity against the pathogen. FliC-Omp22 immunization significantly reduced bacterial loads in infected mice's spleen, lungs, and liver, thereby improving their survival against the lethal infection caused by MDR A. baumannii 58ST. This study suggests that integrating Omp22 into the hypervariable domain of flagellin holds promise for developing an effective vaccine against A. baumannii infections.

Unveiling the impact of Leptospira TolC efflux protein on host tissue adherence, complement evasion, and diagnostic potential.

The TolC family protein of Leptospira is a type I outer membrane efflux protein. Phylogenetic analysis revealed significant sequence conservation among pathogenic Leptospira species (83%-98% identity) compared with intermediate and saprophytic species. Structural modeling indicated a composition of six β-strands and 10 α-helices arranged in two repeats, resembling bacterial outer membrane efflux proteins. Recombinant TolC (rTolC), expressed in a heterologous host and purified via Ni-NTA chromatography, maintained its secondary structural integrity, as verified by circular dichroism spectroscopy. Polyclonal antibodies against rTolC detected native TolC expression in pathogenic Leptospira but not in nonpathogenic ones. Immunoassays and detergent fractionation assays indicated surface localization of TolC. The rTolC's recognition by sera from leptospirosis-infected hosts across species suggests its utility as a diagnostic marker. Notably, rTolC demonstrated binding affinity for various extracellular matrix components, including collagen and chondroitin sulfate A, as well as plasma proteins such as factor H, C3b, and plasminogen, indicating potential roles in tissue adhesion and immune evasion. Functional assays demonstrated that rTolC-bound FH retained cofactor activity for C3b cleavage, highlighting TolC's role in complement regulation. The rTolC protein inhibited both the alternative and the classical pathway-mediated membrane attack complex (MAC) deposition in vitro. Blocking surface-expressed TolC on leptospires using specific antibodies reduced FH acquisition by Leptospira and increased MAC deposition on the spirochete. These findings indicate that TolC contributes to leptospiral virulence by promoting host tissue colonization and evading the immune response, presenting it as a potential target for diagnostic and therapeutic strategies.

Progress and Challenges in the Management of Congenital Cytomegalovirus Infection

Congenital cytomegalovirus (CMV) infection is the most common intrauterine viral infection with a significant impact on the foetus and newborn. Current diagnostic practice includes serological testing for specific antibodies, but there are no global screening protocols. Maternal CMV screening is often performed in conjunction with antenatal ultrasound. While most infections are asymptomatic, severe cases can lead to long-term disability or death. Antiviral therapies, mainly ganciclovir and valganciclovir, are reserved for symptomatic patients, especially those with central nervous system involvement. Although effective, these treatments are associated with significant side effects such as neutropenia and hepatotoxicity. Foscarnet and cidofovir are used as alternatives, but their efficacy and safety require further study in paediatric patient populations. The effectiveness of passive prophylaxis is still uncertain. The lack of universally accepted guidelines for diagnosis, treatment, and prevention and the risk of serious side effects highlight the need for continued research. This review evaluates current therapeutic strategies, discusses their efficacy and associated risks, and highlights the need for innovative approaches to improve outcomes for affected neonates.

Abstract 4144583: Beyond Acute Rejection Screening Following Pediatric Heart Transplant: In Patients Negative for Rejection, Elevated Donor-Derived Cell-Free DNA is Associated with Cardiac Allograft Vasculopathy (CAV) and Donor Specific Antibodies (DSA)

Donor-derived cell-free DNA (dd-cfDNA) has been increasingly used to detect acute rejection (AR). We aimed to compare our institutional dd-cfDNA results to previously published adult and pediatric dd-cfDNA AR cutoffs. We also hypothesized that in the absence of AR, elevated dd-cfDNA would be associated with CAV and positive DSA. Patients (pt) < 18 years at transplant with > 1 dd-cfDNA between 2021-2023 were included. Using dd-cfDNA levels from this cohort, sensitivity, specificity, NPV, and PPV were calculated. False positives and false negatives (FN) were determined using published dd-cfDNA thresholds. AR was defined as decision-to-treat with increased immunosuppression, which was independent of dd-cfDNA in our cohort. In pt without AR, t -test was used to compare the means of dd-cfDNA levels in pt with and without DSA. χ 2 testing was then performed to evaluate the association between dd-cfDNA levels above and below 0.2% and the presence/absence of DSA and CAV. DSA was defined as allele-specific DSA identified by single antigen bead with mean fluorescence intensity >1000, and CAV as any disease by angiography. There were 379 samples among 163 pt, a median of 2 samples per pt, and 32 samples obtained at time of AR. Performance of dd-cfDNA in our cohort vs published dd-cfDNA thresholds is shown in Table 1. The FN rate ranged from 16 to 37% as the dd-cfDNA threshold increased. Mean dd-cfDNA was higher in patients with positive DSA versus those without (0.83% vs 0.19%, p<0.001). In patients that did not meet AR criteria, dd-cfDNA levels > 0.2% were associated with a higher prevalence of positive DSA (n=66) (48% vs 13%, p<0.001), and trended towards a higher prevalence of CAV (n=20) (15% vs 11%, p=0.08). Dd-cfDNA had high sensitivity and NPV for AR but the FN rate using published dd-cfDNA cutoffs was high in our validation cohort. The clinical utility of dd-cfDNA may extend beyond AR screening given increased frequency of DSA and CAV in pt with elevated levels that are negative for AR. We speculate that monitoring intra-pt dd-cfDNA variability will reduce the FN rate when screening for AR in addition to enhancing its clinical utility when monitoring for CAV and DSA.

The association of Helicobacter pylori with adverse pregnancy outcomes in three European birth cohorts.

Helicobacter pylori is a prevalent infection that may complicate pregnancy, but evidence remains limited, controversial and may not apply to all pregnant women. This study aims to evaluate whether Helicobacter pylori is a risk factor for adverse pregnancy outcomes and to identify vulnerable subpopulations. Multiplex serology was utilized to measure blood levels of immunoglobulin G against eight Helicobacter pylori antigens in 1372 pregnant women from three European birth cohorts: BiB (United Kingdom), Rhea (Greece) and INMA (Spain). Outcomes of interest included gestational diabetes mellitus, gestational hypertension, preeclampsia, preterm birth and small for gestational age neonates, as well as prenatal anxiety and depression. Adjusted logistic regression models were used to evaluate the association between Helicobacter pylori seropositivity (overall and by antigen) and antigen specific antibody levels with the outcomes. We examined effect modification of the associations by ethnicity. Helicobacter pylori seropositivity was detected in 18.8% (258/1372) of pregnant women. Preeclampsia was the least common outcome (26/830). Helicobacter pylori seropositivity was associated with the development of two or more adverse pregnancy outcomes (gestational hypertension, gestational diabetes, preterm birth, small gestational age and preeclampsia) [OR:1.32 (95% CI: 1.06-1.65), p-value: 0.01], especially in women with high antibody levels to OMP antigen [OR: 2.12 (95% CI: 1.62-2.76), p-value: 0.001]. Women with high antibody levels to Helicobacter pylori antigens GroEL and NapA were more likely to develop preeclampsia [OR: 2.34 (95% CI: 1.10-8.82), p-value: 0.03; OR: 4.09 (95% CI: 1.4-11.93), p-value 0.01)]. Helicobacter pylori seropositivity increased the odds of developing any hypertensive disorder during pregnancy among women of western ethnicity (948/1372) [OR:3.35 (95% CI: 1.29-8.74), p-value 0.03]. Our study suggests that Helicobacter pylori seropositivity is a risk factor for multiple adverse pregnancy outcomes and particularly in women of western origin for hypertensive disorders during pregnancy. Moreover, pathogen specific characteristics reflected in the antibody responses against OMP, GroEL and NapA seem to determine disease associations.

Seroprevalence and silent infection rate during SARS-CoV-2 pandemic among children and adolescents in Western Pomerania: a multicenter, cross-sectional study-the COVIDKID study.

Limited data on SARS-CoV-2 seroprevalence in rural areas of northern Germany necessitate comprehensive cohort studies. We aimed to evaluate the seroprevalence, silent infection (SI) rates and risk factors for infections among children and adolescents in Western Pomerania from December 2020 to August 2022. In this cross-sectional study, serum or plasma samples from children and adolescents (6 months to 17 years) were collected during routine blood draw. SARS-CoV-2 specific antibodies (S1 and nucleocapsid) and their neutralizing capacity were analyzed using commercially available enzyme-linked immunosorbent and neutralization assays. Socio-demographic data and information about SARS-CoV-2 infection or vaccination were obtained. Multivariable logistic regression was used to identify independent risk factors for SARS-CoV-2 infections and SI. A total of 1,131 blood samples were included into the study. Overall, SARS-CoV-2 seroprevalence was 25.1%, strongly influenced by the pandemic course, predominant virus variants, age and approval of vaccination. SI rate was 5.4% (95%-CI [3.7%-6.8%]) among unvaccinated and undiagnosed children over the entire study period with highest rates among adolescents. Main risk factor despite the time at risk for silent infections was an infected household member (Odds ratio = 9.88, 95%-CI [4.23-22.9], p<0.001). Factors associated with overall infections (known and silent) also include the infection of a household member (Odds ratio = 17.8, 95%-CI [10.7-29.6], p<0.001). We believe that the introduction of governmental measures and systematic test strategies in schools strongly impacted on the SI rate, as we suspect that asymptomatic cases have already been identified, resulting in surprisingly low SI identified in our study.