COBRA N2 NA vaccines induce protective immune responses against influenza viral infection.

Influenza neuraminidase (NA) is a promising target for a broadly protective vaccine. In this study, the Computationally Optimized Broadly Reactive Antigen (COBRA) methodology was used to develop N2 NA vaccine candidates. The unique wild type (WT) N2 sequences of human and swine influenza strains isolated between 1957 and 2019 were used to design the COBRA N2-A NA vaccine, while the unique WT N2 sequences of human influenza strains isolated between 2000 and 2019 were used to design the COBRA N2-B NA vaccine. Sera collected from COBRA N2 NA vaccinated mice showed more broadly reactive antibody responses against a broad panel of H×N2 influenza virus strains than sera collected from mice vaccinated with WT N2 NA vaccines. Antibodies elicited by COBRA or WT N2 NA antigens cross react with recent human H3N2 influenza viruses from different clades, while the antibodies elicited by A/Switzerland/9715293/2013 hemagglutinin (HA) reacted with viruses from the same clade. Furthermore, mice vaccinated with COBRA N2-B NA vaccine had lower viral lung titers compared to mock vaccinated mice when challenged with human H3N2 influenza viruses. Thus, the COBRA N2 NA vaccines elicit broadly protective murine anti-NA antibodies against multiple strains across subtypes and the viral loads were significantly decreased in the lungs of the mice in the COBRA N2 NA vaccine groups, compared to the mice in the mock vaccinated group, indicating that the COBRA-based N2 subtype NA vaccines have a potential to be a component in a universal influenza vaccine.

Isolation and characterization of IgG3 glycan-targeting antibodies with exceptional cross-reactivity for diverse viral families.

Broadly reactive antibodies that target sequence-diverse antigens are of interest for vaccine design and monoclonal antibody therapeutic development because they can protect against multiple strains of a virus and provide a barrier to evolution of escape mutants. Using LIBRA-seq (linking B cell receptor to antigen specificity through sequencing) data for the B cell repertoire of an individual chronically infected with human immunodeficiency virus type 1 (HIV-1), we identified a lineage of IgG3 antibodies predicted to bind to HIV-1 Envelope (Env) and influenza A Hemagglutinin (HA). Two lineage members, antibodies 2526 and 546, were confirmed to bind to a large panel of diverse antigens, including several strains of HIV-1 Env, influenza HA, coronavirus (CoV) spike, hepatitis C virus (HCV) E protein, Nipah virus (NiV) F protein, and Langya virus (LayV) F protein. We found that both antibodies bind to complex glycans on the antigenic surfaces. Antibody 2526 targets the stem region of influenza HA and the N-terminal domain (NTD) region of SARS-CoV-2 spike. A crystal structure of 2526 Fab bound to mannose revealed the presence of a glycan-binding pocket on the light chain. Antibody 2526 cross-reacted with antigens from multiple pathogens and displayed no signs of autoreactivity. These features distinguish antibody 2526 from previously described glycan-reactive antibodies. Further study of this antibody class may aid in the selection and engineering of broadly reactive antibody therapeutics and can inform the development of effective vaccines with exceptional breadth of pathogen coverage.

Variant-specific antibody profiling for tracking SARS-CoV-2 variant infections in children and adolescents.

Monitoring the seroprevalence of SARS-CoV-2 in children and adolescents can provide valuable information for effective SARS-CoV-2 surveillance, and thus guide vaccination strategies. In this study, we quantified antibodies against the spike S1 domains of several SARS-CoV-2 variants (wild-type, Alpha, Delta, and Omicron variants) as well as endemic human coronaviruses (HCoVs) in 1,309 children and adolescents screened between December 2020 and March 2023. Their antibody binding profiles were compared with those of 22 pre-pandemic samples from children and adolescents using an in-house Luminex®-based Corona Array (CA). The primary objectives of this study were to (i) monitor SARS-CoV-2-specific antibodies in children and adolescents, (ii) evaluate whether the S1-specific antibody response can identify the infecting variant of concern (VoC), (iii) estimate the prevalence of silent infections, and (iv) test whether vaccination or infection with SARS-CoV-2 induce HCoV cross-reactive antibodies. Both SARS-CoV-2 infection and vaccination induced a robust antibody response against the S1 domain of WT and VoCs in children and adolescents. Antibodies specific for the S1 domain were able to distinguish between SARS-CoV-2 VoCs in infected children. The serologically identified VoC was typically the predominant VoC at the time of infection. Furthermore, our highly sensitive CA identified more silent SARS-CoV-2 infections than a commercial ELISA (12.1% vs. 6.3%, respectively), and provided insights into the infecting VoC. Seroconversion to endemic HCoVs occurred in early childhood, and vaccination or infection with SARS-CoV-2 did not induce HCoV S1 cross-reactive antibodies. In conclusion, the antibody response to the S1 domain of the spike protein of SARS-CoV-2 is highly specific, providing information about the infecting VoC and revealing clinically silent infections.

Enhanced and cross-reactive in vitro memory B cell response against Epstein-Barr virus nuclear antigen 1 in multiple sclerosis.

Multiple sclerosis (MS) is a prototypical autoimmune disease of the central nervous system (CNS). In addition to CD4+ T cells, memory B cells are now recognized as a critical cell type in the disease. This is underlined by the fact that the best-characterized environmental risk factor for MS is the Epstein-Barr virus (EBV), which can infect and persist in memory B cells throughout life. Several studies have identified changes in anti-EBV immunity in patients with MS. Examples include elevated titers of anti-EBV nuclear antigen 1 (EBNA1) antibodies, interactions of these with the MS-associated HLA-DR15 haplotype, and molecular mimicry with MS autoantigens like myelin basic protein (MBP), anoctamin-2 (ANO2), glial cell adhesion molecule (GlialCAM), and alpha-crystallin B (CRYAB). In this study, we employ a simple in vitro assay to examine the memory B cell antibody repertoire in MS patients and healthy controls. We replicate previous serological data from MS patients demonstrating an increased secretion of anti-EBNA1380-641 IgG in cell culture supernatants, as well as a positive correlation of these levels with autoantibodies against GlialCAM262-416 and ANO21-275. For EBNA1380-641 and ANO21-275, we provide additional evidence suggesting antibody cross-reactivity between the two targets. Further, we show that two efficacious MS treatments - natalizumab (NAT) and autologous hematopoietic stem cell transplantation (aHSCT) - are associated with distinct changes in the EBNA1-directed B cell response and that these alterations can be attributed to the unique mechanisms of action of these therapies. Using an in vitro system, our study confirms MS-associated changes in the anti-EBNA1 memory B cell response, EBNA1380-641 antibody cross-reactivity with ANO21-275, and reveals treatment-associated changes in the immunoglobulin repertoire in MS.

Longevity of hybrid immunity against SARS-CoV-2 in adults vaccinated with an adenovirus-based COVID-19 vaccine.

BACKGROUND: Hybrid immunity provides better protection against COVID-19 than vaccination or prior natural infection alone. It induces high magnitude and broadly cross-reactive neutralising anti-Spike IgG antibodies. However, it is not clear how long these potent antibodies last, especially in the context of adenovirus-based COVID-19 vaccines. METHODS: We conducted a longitudinal cohort study and enrolled 20 adults who had received an adenovirus-based COVID-19 vaccine before a laboratory-confirmed SARS-CoV-2 infection. We followed up the study participants for 390 days post the initial breakthrough infection. We assessed the longevity and cross-reactive breadth of serum antibodies against SARS-CoV-2 variants of concern (VOCs), including Omicron. RESULTS: The binding anti-Spike IgG antibodies remained within the reported putative levels for at least 360 days and were cross-neutralising against Beta, Gamma, Delta, and Omicron. During the follow up period, a median of one SARS-CoV-2 re-infection event was observed across the cohort, but none resulted in severe COVID-19. Moreover, the re-exposure events were associated with augmented anti-Spike and anti-RBD IgG antibody titres. CONCLUSIONS: This study confirms that hybrid immunity provides durable broadly cross-reactive antibody immunity against SARS-CoV-2 variants of concern for at least a year (360 days), and that it is further augment by SARS-CoV-2 re-exposure.

Unraveling wasp sensitization in a patient with systemic mastocytosis by CAP-inhibition assay.

Systemic mastocytosis (SM) is a clonal mast cell disorder that can lead to potentially severe anaphylactic reactions. Hymenoptera sting is one of the most frequent triggers of anaphylaxis in these patients, and diagnosis of indolent SM (ISM) without skin involvement (ISMs) is not rare. In this subgroup of patients, venom immunotherapy (VIT) is an effective treatment decreasing subsequent systemic reactions, and lifelong administration is recommended. An individualized diagnosis is necessary to offer the most adequate VIT, and molecular diagnosis (MD) may be useful to discriminate between primary sensitization and cross-reactivity. Nevertheless, other techniques such as ImmunoCAP inhibition assays may be necessary to identify the genuine sensitization to offer the most suitable VIT. We present a male patient with an anaphylactic reaction following several wasp stings. The patient was diagnosed with ISM, and allergy to both Polistes dominula and Vespula sp venom was confirmed. In this scenario, MD did not discriminate between a genuine double sensitization and venom cross-reactivity between both vespids. Thus, CAP-inhibition assay was performed. This case indicated the importance of an accurate diagnosis of hymenoptera venom allergy (HVA). It also highlights the usefulness of CAP-inhibition assays when MD fails to distinguish between genuine double Polistes-Vespula sensitization and cross-reactivity.

Inter-individual and inter-regional variability of breast milk antibody reactivity to bacterial lipopolysaccharides.

Breast milk is a vital source of nutrients, prebiotics, probiotics, and protective factors, including antibodies, immune cells and antimicrobial proteins. Using bacterial lipopolysaccharide arrays, we investigated the reactivity and specificity of breast milk antibodies towards microbial antigens, comparing samples from rural Kenya and urban Switzerland. Results showed considerable variability in antibody reactivity both within and between these locations. Kenyan breast milk demonstrated broad reactivity to bacterial lipopolysaccharides, likely due to increased microbial exposure. Antibodies primarily recognized the O-antigens of lipopolysaccharides and showed strong binding to specific carbohydrate motifs. Notably, antibodies against specific Escherichia coli O-antigens showed cross-reactivity with parasitic pathogens like Leishmania major and Plasmodium falciparum, thus showing that antibodies reacting against lipopolysaccharide O-antigens can recognize a wide range of antigens beyond bacteria. The observed diversity in antigen recognition highlights the significance of breast milk in safeguarding infants from infections, particularly those prevalent in specific geographic regions. The findings also offer insights for potential immunobiotic strategies to augment natural antibody-mediated defense against diverse pathogens.

Bispecific killer cell engagers employing species cross-reactive NKG2D binders redirect human and murine lymphocytes to ErbB2/HER2-positive malignancies.

NKG2D is an activating receptor expressed by natural killer (NK) cells and other cytotoxic lymphocytes that plays a pivotal role in the elimination of neoplastic cells through recognition of different stress-induced cell surface ligands (NKG2DL). To employ this mechanism for cancer immunotherapy, we generated NKG2D-engaging bispecific antibodies that selectively redirect immune effector cells to cancer cells expressing the tumor-associated antigen ErbB2 (HER2). NKG2D-specific single chain fragment variable (scFv) antibodies cross-reactive toward the human and murine receptors were derived by consecutive immunization of chicken with the human and murine antigens, followed by stringent screening of a yeast surface display immune library. Four distinct species cross-reactive (sc) scFv domains were selected, and reformatted into a bispecific engager format by linking them via an IgG4 Fc domain to a second scFv fragment specific for ErbB2. The resulting molecules (termed scNKAB-ErbB2) were expressed as disulfide-linked homodimers, and demonstrated efficient binding to ErbB2-positive cancer cells as well as NKG2D-expressing primary human and murine lymphocytes, and NK-92 cells engineered with chimeric antigen receptors derived from human and murine NKG2D (termed hNKAR and mNKAR). Two of the scNKAB-ErbB2 molecules were found to compete with the natural NKG2D ligand MICA, while the other two engagers interacted with an epitope outside of the ligand binding site. Nevertheless, all four tested scNKAB-ErbB2 antibodies were similarly effective in redirecting the cytotoxic activity of primary human and murine lymphocytes as well as hNKAR-NK-92 and mNKAR-NK-92 cells to ErbB2-expressing targets, suggesting that further development of these species cross-reactive engager molecules for cancer immunotherapy is warranted.

Pollen-Food Allergy Syndrome: From Food Avoidance to Deciphering the Potential Cross-Reactivity between Pru p 3 and Ole e 7.

BACKGROUND: Cross-reactivity between nonspecific lipid transfer proteins could cause anaphylaxis, further influencing food avoidance and nutrient deficiencies. The one affecting olive pollen (Ole e 7) and peach (Pru p 3) may underlie a variety of pollen-food syndromes, though a deep molecular analysis is necessary. METHODS: Three Ole e 7-monosensitised patients (MON_OLE), three Pru p 3-monosensitised patients (MON_PRU) and three bisensitised patients (BI) were selected. For epitope mapping, both digested proteins were incubated with patient sera, and the captured IgE-bound peptides were characterised by LC-MS. RESULTS: The analysis revealed two Ole e 7 epitopes and the three Pru p 3 epitopes previously described. Interestingly, the "KSALALVGNKV" Ole e 7 peptide was recognised by MON_OLE, BI and MON_PRU patients. Conversely, all patients recognised the "ISASTNCATVK" Pru p 3 peptide. Although complete sequence alignment between both proteins revealed 32.6% identity, local alignment considering seven residue fragments showed 50 and 57% identity when comparing "ISASTNCATVK" with Ole e 7 and "KSALALVGNKV" with Pru p 3. CONCLUSIONS: This study mapped sIgE-Ole e 7-binding epitopes, paving the way for more precise diagnostic tools. Assuming non-significant sequence similarity, structural homology and shared key residues may underlie the potential cross-reactivity between Ole e 7 and Pru p 3 nsLTPs.

[Analysis of the effectiveness of cross-reactive carbohydrate antigen determinant antibody adsorbents in identifying allergen-specific IgE antibodies].

This study aimed to investigate the influence of anti-cross-reactive carbohydrate determinant IgE antibodies (anti-CCD IgE) on the detection of allergen-specific IgE (sIgE) antibodies, as well as the application value of anti-CCD IgE adsorbents in detecting allergen sIgE. In this cross-sectional study, a total of 2 636 test samples from patients who received treatment in West China Hospital of Sichuan University and tested allergen sIgE using the western blot method from October 2020 to May 2021 were analyzed. In these samples, 709 samples tested postive of allergen sIgE. 46 stochastic venous serum samples that tested positive in both sIgE and anti-CCD IgE and 1 serum sample that tested positive in sIgE but negative in anti-CCD IgE were collected. These samples were processed by anti-CCD IgE adsorbents, followed by allergen sIgE detection. The difference between the two detection results before and after adsorption was analyzed. The allergen test results showed that the positive rate of anti-CCD IgE in samples was 2.6% (69/2 636) during the period of sample collection. After treatment with anti-CCD IgE adsorbents, the top three allergen-sIgE of the positive rate changed from tree combination 2 (willow/poplar/elm), common ragweed and peanut to dust mite combination, cockroach and crab. The positive anti-CCD IgE results of 46 samples all turned negative and the total positive sIgE antibody dropped by 62.8%; the positive rate of sIgE antibodies with the class result ≥2 significantly decreased after treatment with anti-CCD IgE adsorbents, especially the positive rate of common ragweed dropped by 96.2%. The results of positive samples showed that multiple sIgE antibodies declined by different ranges, involving up to 11 antibodies with a maximum decline of 4 classes. Strongly positive sIgE antibodies (the class result ≥4) also had a high conversion rate of negative (25.0%-100%). The positive sIgE antibodies in about 60% of the samples decreased by more than 2, and the sIgE antibodies in 17.4% of the samples turned completely negative. There was no change in the allergen sIgE detection results of the sample with negative anti-CCD IgE after treatment. In conclusion, sIgE antibodies including targeting common ragweed, humulus, tree combination 2 (willow/poplar/elm), etc. are susceptible to false positives caused by anti-CCD IgE. Treatment of samples with anti-CCD IgE adsorbents can significantly reduce the risk of false positives caused by anti-CCD IgE. It is necessary to pretreat samples that were anti-CCD IgE positive with anti-CCD IgE adsorbents, which can make laboratory results more accurate and provide a reference for diagnosis and prevention of allergic diseases.

Cephalosporin Allergy: Updates on Diagnostic Testing.

PURPOSE OF REVIEW: Cephalosporins are one of the most prescribed antibiotics worldwide and are implicated in a wide range of hypersensitivity reactions (HSR). This review summarizes recent updates in cephalosporin hypersensitivity with a focus on diagnostic testing. RECENT FINDINGS: Reported testing strategies to evaluate different immediate and delayed cephalosporin HSR have included skin testing, in vitro testing, and diagnostic drug challenges. However, the diagnostic performance of in vivo and in vitro tests remains unclear across different hypersensitivity endotypes; adequately powered studies investigating the true positive and negative predictive value of these diagnostic modalities are needed using the reference standard of drug challenges to define cephalosporin hypersensitivity. Refinement of diagnostic testing should be guided by growth in our understanding of cephalosporin antigenic determinants. This growth will be crucial in driving further clarification of cross-reactivity between cephalosporins, and potentially delineating streamlined evaluation processes resulting in reduced unnecessary antibiotic avoidance.

Molecular mimicry in multisystem inflammatory syndrome in children.

Multisystem inflammatory syndrome in children (MIS-C) is a severe, post-infectious sequela of SARS-CoV-2 infection1,2, yet the pathophysiological mechanism connecting the infection to the broad inflammatory syndrome remains unknown. Here we leveraged a large set of samples from patients with MIS-C to identify a distinct set of host proteins targeted by patient autoantibodies including a particular autoreactive epitope within SNX8, a protein involved in regulating an antiviral pathway associated with MIS-C pathogenesis. In parallel, we also probed antibody responses from patients with MIS-C to the complete SARS-CoV-2 proteome and found enriched reactivity against a distinct domain of the SARS-CoV-2 nucleocapsid protein. The immunogenic regions of the viral nucleocapsid and host SNX8 proteins bear remarkable sequence similarity. Consequently, we found that many children with anti-SNX8 autoantibodies also have cross-reactive T cells engaging both the SNX8 and the SARS-CoV-2 nucleocapsid protein epitopes. Together, these findings suggest that patients with MIS-C develop a characteristic immune response to the SARS-CoV-2 nucleocapsid protein that is associated with cross-reactivity to the self-protein SNX8, demonstrating a mechanistic link between the infection and the inflammatory syndrome, with implications for better understanding a range of post-infectious autoinflammatory diseases.

Fourth dose bivalent COVID-19 vaccines outperform monovalent boosters in eliciting cross-reactive memory B cells to Omicron subvariants.

Bivalent COVID-19 vaccines comprising ancestral Wuhan-Hu-1 (WH1) and the Omicron BA.1 or BA.5 subvariant elicit enhanced serum antibody responses to emerging Omicron subvariants. Here, we characterized the RBD-specific memory B cell (Bmem) response following a fourth dose with a BA.1 or BA.5 bivalent vaccine, in direct comparison with a WH1 monovalent fourth dose. Healthcare workers previously immunized with mRNA or adenoviral vector monovalent vaccines were sampled before and one month after a fourth dose with a monovalent or a BA.1 or BA.5 bivalent vaccine. Serum neutralizing antibodies (NAb) were quantified, as well as RBD-specific Bmem with an in-depth spectral flow cytometry panel including recombinant RBD proteins of the WH1, BA.1, BA.5, BQ.1.1, and XBB.1.5 variants. Both bivalent vaccines elicited higher NAb titers against Omicron subvariants compared to the monovalent vaccine. Following either vaccine type, recipients had slightly increased WH1 RBD-specific Bmem numbers. Both bivalent vaccines significantly increased WH1 RBD-specific Bmem binding of all Omicron subvariants tested by flow cytometry, while recognition of Omicron subvariants was not enhanced following monovalent vaccination. IgG1+ Bmem dominated the response, with substantial IgG4+ Bmem only detected in recipients of an mRNA vaccine for their primary dose. Thus, Omicron-based bivalent vaccines can significantly boost NAb and Bmem specific for ancestral WH1 and Omicron variants and improve recognition of descendent subvariants by pre-existing, WH1-specific Bmem beyond that of a monovalent vaccine. This provides new insights into the capacity of variant-based mRNA booster vaccines to improve immune memory against emerging SARS-CoV-2 variants and potentially protect against severe disease. ONE-SENTENCE SUMMARY: Omicron BA.1 and BA.5 bivalent COVID-19 boosters, used as a fourth dose, increase RBD-specific Bmem cross-recognition of Omicron subvariants, both those encoded by the vaccines and antigenically distinct subvariants, further than a monovalent booster.

Enhanced Assessment of Cross-Reactive Antigenic Determinants within the Spike Protein.

Despite successful vaccination efforts, the emergence of new SARS-CoV-2 variants poses ongoing challenges to control COVID-19. Understanding humoral responses regarding SARS-CoV-2 infections and their impact is crucial for developing future vaccines that are effective worldwide. Here, we identified 41 immunodominant linear B-cell epitopes in its spike glycoprotein with an SPOT synthesis peptide array probed with a pool of serum from hospitalized COVID-19 patients. The bioinformatics showed a restricted set of epitopes unique to SARS-CoV-2 compared to other coronavirus family members. Potential crosstalk was also detected with Dengue virus (DENV), which was confirmed by screening individuals infected with DENV before the COVID-19 pandemic in a commercial ELISA for anti-SARS-CoV-2 antibodies. A high-resolution evaluation of antibody reactivity against peptides representing epitopes in the spike protein identified ten sequences in the NTD, RBD, and S2 domains. Functionally, antibody-dependent enhancement (ADE) in SARS-CoV-2 infections of monocytes was observed in vitro with pre-pandemic Dengue-positive sera. A significant increase in viral load was measured compared to that of the controls, with no detectable neutralization or considerable cell death, suggesting its role in viral entry. Cross-reactivity against peptides from spike proteins was observed for the pre-pandemic sera. This study highlights the importance of identifying specific epitopes generated during the humoral response to a pathogenic infection to understand the potential interplay of previous and future infections on diseases and their impact on vaccinations and immunodiagnostics.

Histoplasma capsulatum urinary antigen detection in a kidney transplant recipient with acute paracoccidioidomycosis: Case study and literature review.

BACKGROUND: Paracoccidioidomycosis (PCM) and histoplasmosis are endemic fungal diseases in South America. Both can lead to lung involvement with fungal dissemination progressing to systemic and severe clinical manifestations, especially in immunosuppressed hosts. As the population of immunosuppressed individuals has been rising, a higher occurrence of fungal infections is predicted in this setting. This poses challenges regarding the differential diagnosis due to overlapping clinical and laboratorial findings, hampering the management of cases. OBJECTIVES: In this study, the authors discuss the occurrence of a false-positive Histoplasma urinary antigen detection in a kidney transplant recipient with acute PCM. Given the scarce information about this subject, a review on literature data is provided. METHODS: A comprehensive literature search was conducted to investigate previous studies that found cross-reactivity between Histoplasma urinary antigen assays in human patients with confirmed diagnosis of PCM. Additionally, an update of PCM in transplant recipients is provided. FINDINGS: The included studies reported 120 samples from patients with PCM tested for Histoplasma antigen, presenting an overall cross-reactivity of 51.67% and 17 cases of PCM in transplant recipients. CONCLUSIONS: The galactomannan urinary antigen developed to diagnose histoplasmosis can cross react with PCM, which may represent a concern in countries where both mycoses overlap.

Fully human monoclonal antibodies against Ebola virus possess complete protection in a hamster model.

Ebola disease is a lethal viral hemorrhagic fever caused by ebolaviruses within the Filoviridae family with mortality rates of up to 90%. Monoclonal antibody (mAb) based therapies have shown great potential for the treatment of EVD. However, the potential emerging ebolavirus isolates and the negative effect of decoy protein on the therapeutic efficacy of antibodies highlight the necessity of developing novel antibodies to counter the threat of Ebola. Here, 11 fully human mAbs were isolated from transgenic mice immunized with GP protein and recombinant vesicular stomatitis virus-bearing GP (rVSV-EBOV GP). These mAbs were divided into five groups according to their germline genes and exhibited differential binding activities and neutralization capabilities. In particular, mAbs 8G6, 2A4, and 5H4 were cross-reactive and bound at least three ebolavirus glycoproteins. mAb 4C1 not only exhibited neutralizing activity but no cross-reaction with sGP. mAb 7D8 exhibited the strongest neutralizing capacity. Further analysis on the critical residues for the bindings of 4C1 and 8G6 to GPs was conducted using antibodies complementarity-determining regions (CDRs) alanine scanning. It has been shown that light chain CDR3 played a crucial role in binding and neutralization and that any mutation in CDRs could not improve the binding of 4C1 to sGP. Importantly, mAbs 7D8, 8G6, and 4C1 provided complete protections against EBOV infection in a hamster lethal challenge model when administered 12 h post-infection. These results support mAbs 7D8, 8G6, and 4C1 as potent antibody candidates for further investigations and pave the way for further developments of therapies and vaccines.

Efficacy and safety evaluation of cross-reactive Fibroblast activation protein scFv-based CAR-T cells.

Introduction: Fibroblast activation protein (FAP) overexpression on cancer-associated fibroblasts (CAFs) is associated with poor prognosis and worse clinical outcomes. Selective ablation of pro-tumorgenic FAP+ stromal cells with CAR-T cells may be a new therapeutic strategy. However, the clinical use of FAP-CAR T cells is suggested to proceed with caution for occasional poor efficacy and induction of on-target off-tumor toxicity (OTOT), including lethal osteotoxicity and cachexia. Hence, more investigations and preclinical trials are required to optimize the FAP-CAR T cells and to approve their safety and efficacy. Methods: In this study, we designed second-generation CAR T cells targeting FAP with 4-1BB as a co-stimulatory molecule, and tested their cytotoxicity against FAP-positive cells (hFAP-HT1080 cells and a variety of primary CAFs) in vitro and in Cell line-derived xenograft (CDX) and a patient-derived xenograft (PDX) model. Results: Results showed that our FAP-CAR T cells were powerfully potent in killing human and murine FAP-positive tumor cells and CAFs in multiple types of tumors in BALB/c and C57BL/6 mice and in patient-derived xenografts (PDX) model. And they were proved to be biologically safe and exhibit low-level OTOT. Discussion: Taken together, the human/murine cross-reactive FAP-CAR T cells were powerfully potent in killing human and murine FAP positive tumor cells and CAFs. They were biologically safe and exhibit low-level OTOT, warranting further clinical investigation into our FAP-CAR T cells.

Understanding the landscape of the SARS-CoV-2-specific T cells post-omicron surge.

Emerging evidence shows increased humoral response post-omicron surge, but research on T cell responses is limited. This study investigated the durability, magnitude, and breadth of SARS-CoV-2-spike-specific T cell responses in 216 two-dose vaccinated individuals pre- and post-omicron surge. Post-surge samples showed enhanced T cell responses, indicating widespread asymptomatic exposure to omicron. Further analysis of 105 individuals with multiple exposures to SARS-CoV-2 through boosters or infections showed that post-omicron, two-dose vaccinated individuals had T cell responses comparable to those of COVID-19 convalescents or boosted individuals. Additionally, we report cross-reactive T cell responses against omicron sub-variants, including BA2.86, remained strong, with preserved frequencies of spike-specific stem-cell-like memory T cells. In silico prediction indicates that mutated epitopes of JN.1 and KP.2 retain over 95.6% of their HLA binding capability. Overall, our data suggests that T cell responses are sustained, enhanced, and cross-reactive against emerging SARS-CoV-2 variants following symptomatic or asymptomatic omicron infection.

Impact of pre-existing cross-reactive antibodies on cyclic dengue outbreaks in the hyperendemic region of Bali, Indonesia.

The four serotypes of the dengue virus (DENV) cause a range of diseases ranging from mild fever to severe conditions. Understanding the immunological interactions among the four serotypes is crucial in comprehending the dynamics of serotype shifting during outbreaks in areas where all four serotypes co-circulate. Hence, we evaluated the neutralizing antibody and antibody-dependent enhancement responses against the four DENV serotypes using acute-phase plasma samples collected from 48 laboratory-confirmed dengue patients during a dengue outbreak in Bali, Indonesia in 2022. Employing single-round infectious particles to exclusively investigate immunogenicity to the structural surface proteins of DENV, which are the targets of antibodies, we found that individuals with a probable prior history of DENV-1 infection exhibited increased susceptibility to secondary DENV-3 infection, attributed to cross-reactive antibodies with limited neutralizing activity against DENV-3 (geometric mean 50 % neutralization titer (GMNT50) = 47.6 ± 11.5). This susceptibility was evident in vitro, with a mean fold enhancement of 28.4 ± 33.9. Neutralization titers against DENV-3 were significantly lower compared to other serotypes (DENV-1 GMNT50 = 678.1 ± 9.0; DENV-2 GMNT50 = 210.5 ± 8.7; DENV-4 GMNT50 = 95.14 ± 7.0). We demonstrate that prior immunity to one serotype provides limited cross-protection against the other serotypes, influencing the dominant serotype in subsequent outbreaks. These findings underscore the complexity of dengue immunity and its implications for vaccine design and transmission dynamics in hyperendemic regions.

A broadly cross-reactive i-body to AMA1 potently inhibits blood and liver stages of Plasmodium parasites.

Apical membrane antigen-1 (AMA1) is a conserved malarial vaccine candidate essential for the formation of tight junctions with the rhoptry neck protein (RON) complex, enabling Plasmodium parasites to invade human erythrocytes, hepatocytes, and mosquito salivary glands. Despite its critical role, extensive surface polymorphisms in AMA1 have led to strain-specific protection, limiting the success of AMA1-based interventions beyond initial clinical trials. Here, we identify an i-body, a humanised single-domain antibody-like molecule that recognises a conserved pan-species conformational epitope in AMA1 with low nanomolar affinity and inhibits the binding of the RON2 ligand to AMA1. Structural characterisation indicates that the WD34 i-body epitope spans the centre of the conserved hydrophobic cleft in AMA1, where interacting residues are highly conserved among all Plasmodium species. Furthermore, we show that WD34 inhibits merozoite invasion of erythrocytes by multiple Plasmodium species and hepatocyte invasion by P. falciparum sporozoites. Despite a short half-life in mouse serum, we demonstrate that WD34 transiently suppressed P. berghei infections in female BALB/c mice. Our work describes the first pan-species AMA1 biologic with inhibitory activity against multiple life-cycle stages of Plasmodium. With improved pharmacokinetic characteristics, WD34 could be a potential immunotherapy against multiple species of Plasmodium.