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Swine acute diarrhoea syndrome coronavirus (SADS-CoV) causes vomiting, severe diarrhoea and death in newborn piglets. The spike (S) protein plays a crucial role in promoting virus invasion and inducing neutralizing antibody production. In this study, the extracellular region of the S protein was used as an immunogen to immunize BALB/c mice. After immunization, B cells were collected, fused with SP2/0 myeloma cells, cultured and subcloned, and a cell line capable of secreting neutralizing antibodies was obtained and named as 5D6. Additionally, it was determined that the 5D6 mAb could be used as the primary antibody for western blotting and indirect immunofluorescence assay (IFA) to detect SADS-CoV. Further studies indicated that the 5D6 mAb binds to the 136STSHAAD142 motif, which located in the N-terminal domain (NTD) of the spike protein. This result suggested that the NTD of the S protein can induce the production of neutralizing antibodies. Amino acid sequence alignment revealed that the epitope of the 5D6 mAb was conserved among SADS-CoV strains. This study helps elucidate the S protein function of SADS-CoV, and the 5D6 mAb may be used to develop diagnostic and treatment tools for detecting SADS-CoV infection. [ABSTRACT FROM AUTHOR]

Background: Defining the protective thresholds against the severe-acute-respiratory-syndrome-related corona virus-2 pandemic is a crucial challenge. To reduce the risks of severe disease, hospitalization, and death, various COVID-19 vaccines have been rapidly developed. Aim of the work: This study aimed to assess the impact of three common COVID-19 vaccine types; two mRNA COVID-19 vaccines: (Pfizer/BioNTech's BNT162b2 and Moderna's mRNA-1273), one adenoviral vector vaccine: Oxford/AstraZeneca's ChAdOx1, and one inactivated vaccine (Sinovac Biotech/China's Sinovac) on the level of neutralizing antibodies, considering factors such as vaccine type, demographic characteristics, and hybrid immunity. We conducted a direct comparative analysis involving 300 healthcare workers, both with and without prior SARS-CoV-2 infection (B.1, C.36.3, and AY.32 (Delta) variants). Neutralizing antibodies levels were measured at baseline (before vaccination), before the second dose, and six months after the second dose. Results: The results showed a significant increase in neutralizing antibodies levels after complete vaccination with all vaccine types. Among healthcare workers, those vaccinated with mRNA vaccines (Moderna or Pfizer) exhibited the highest neutralizing antibodies titers, followed by AstraZeneca, and finally Sinovac with the lowest titer. On studying the effect of previous COVID-19 infection after vaccination, no significant difference in neutralizing antibodies levels was observed between healthcare workers vaccinated with mRNA or AstraZeneca vaccines, both with prior COVID-19 infection, following the first and six months after the second dose. Conclusion: These findings suggest that individuals with prior COVID-19 may only require a single dose of mRNA or AstraZeneca vaccines to achieve a similar level of immunization as those without prior COVID-19 who completed the vaccination program. Highlights: There is a significant increase in neutralizing antibodies levels after complete vaccination against COVID-19 Vaccination with mRNA vaccines exhibits the highest neutralizing antibodies titers. Vaccination with Sinovac exhibits the lowest neutralizing antibodies titers. [ABSTRACT FROM AUTHOR]

High levels of pre-existing antibodies are amajor challenge for the application of viral vectors since they can severely limit their efficacy. To identify promising candidates among adeno-associated virus (AAV) based vectors for future gene therapies for the treatment of hereditary neuromuscular disorders (NMDs), we investigated the antibody levels in sera from patients with NMDs against 18 AAV types, including 11 AAVs with wild-type capsids, 5 AAVs with peptide-modified capsids and 2 AAVs with shuffled capsids. With regard to the wild-type capsid AAVs, the lowest binding antibody levels were detected against AAV6, AAV5, AAV12 and AAV9, whereas the highest binding antibody levels were detected against AAV10, AAV8, AAV1, and AAV2. The lowest neutralizing antibody levels againstwild-type AAVs were detected against AAV12, AAV5, AAV9, AAV7, AAV8 and AAV10, and the highest neutralizing antibody levels were detected against AAV13, AAV2 and AAV3. Interestingly, the influence of peptide modifications or shuffling of AAV capsids on antibody binding and AAV neutralization seemed to depend on the parental AAV. While the sex of the serum donors had no significant impact on binding or neutralizing antibody levels, we observed a trend to higher binding antibodies in older serum donors against some AAV types and a clear positive correlation of neutralizing antibody titers with the age of the serum donors. The disease status on the other hand did not have a meaningful impact on antibody levels, with no changes in AAV neutralization. Our data indicate that several wild-type or peptide-modified AAV may be good candidates for therapeutic application due to low pre-existing antibody levels, and that the age of potential recipients rather than their health status with regard to NMDs has the biggest impact on vector applicability. [ABSTRACT FROM AUTHOR]

Introduction: Solid organ transplant (SOT) recipients display weak seroconversion and neutralizing antibody (NAb) responses after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and remain at risk of severe coronavirus disease 2019 (COVID-19). While B-cell memory is the hallmark of serological immunity, its role in driving successful vaccine responses and providing immune protection in SOT patients remains unclear. Methods: We investigated the function and interplay of SARS-CoV-2-specific memory B cells (mBc), different cytokineproducing T cells, and cross-reactive NAb in driving seroconversion and protection against COVID-19 in two cohorts. First, we studied a large cohort of 148 SOT recipients and 32 immunocompetent individuals who underwent several vaccinations. Subsequently, we assessed 25 SOT patients participating in a randomized controlled trial to compare two different immunosuppressive strategies for allowing successful seroconversion and memory-cell responses after booster vaccination. Results: We corroborate previous findings that B- and T-cell memory responses are weaker and more delayed in SOT patients than in immunocompetent (IC) individuals; however, within the SOT cohort, we found that these responses are relatively stronger and more robust in patients not receiving mycophenolate mofetil (MMF)-based therapies. Anti-spike IgG titers strongly correlated with RBD-specific IgG-producing mBc, with both displaying broad viral cross reactivity. Prebooster SARS-CoV-2-specific mBc and IL-2-producing T cells accurately predicted Nab seroconversion (AUC, 0.828) and protection against severe COVID-19. While switching unresponsive SOT patients from calcineurin inhibitors (CNI)/MMF to a low-exposure CNI/mTOR-i regimen favored wider SARS-CoV-2-specific immune responses after a fourth booster vaccination, preformed RBD-specific mBc predicted NAb seroconversion. Discussion: Our study adds new insights into the pathobiology of immune memory and highlights the pivotal role of SARS-CoV-2-specific mBc in promoting immune protection inSOT patients. [ABSTRACT FROM AUTHOR]

Background Rapidly evolving RNA viruses, such as human norovirus, generate extraordinary sequence diversity, posing a significant challenge to vaccine design. This diversity, coupled with short-lasting natural immunity, leads to reinfection throughout one's lifetime. How reexposure shapes humoral immunity to future norovirus strains remains incompletely understood. Methods We profiled the antibody responses following 2 community gastroenteritis outbreaks with GII.2 and GII.6 noroviruses in 1971. Using diverse virus-like particles (VLPs), enzyme-linked immunosorbent assay (ELISA), and carbohydrate-blocking assays (surrogate for neutralization), we examined the antibody response at acute and convalescent timepoints following GII.6 infection. Results Convalescent sera displayed strong homologous blocking, demonstrating a 5-fold increase in GII.6 carbohydrate blockade over acute samples, and broad blocking of diverse archival and modern GII.6 noroviruses. Convalescent sera displayed limited carbohydrate blocking of heterotypic VLPs, despite high ELISA binding titers. Select individuals developed broad cross-genotype blockade, but this response was established before the second outbreak. Finally, we applied a novel competitive carbohydrate-blocking assay to demonstrate the epitope specificity and discrete compartments of the neutralizing response. Conclusions Our data show that infection generates narrow, focused immunity directed toward the infecting genotype. We did detect broad cross-blocking in specific individuals, but these responses could be attributed to diverse, genotype-specific antibodies predating GII.6 infection. [ABSTRACT FROM AUTHOR]

Longitudinal humoral immune response to inactivated COVID-19 vaccines among people living with HIV (PLWH) have not yet been systematically investigated. We conducted a 6-month longitudinal study among vaccinated PLWH and HIV-Negative Controls (HNC) to determine whether the humoral immune response effects of the inactivated COVID-19 vaccine are different between the two groups of people. Totally, 46 PLWH and 38 HNC who received the inactivated COVID-19 vaccine on days 0 and 28 were enrolled. The SARS-CoV-2 neutralizing antibodies (nAbs) and total specific IgM and IgG antibodies were examined on Day 0-Day190. The level and positive seroconversion rate of nAbs peaked on Day 42 in HNC while peaked on Day 70 in PLWH, then decreased gradually with the extension of the vaccination period after the peaks. The peak level of nAbs in PLWH on Day 70, (GMC 8.07 BAU/mL, 95% CI 5.67-11.48) was significantly lower than in HNC on Day 42 (GMC 18.28 BAU/mL, 95% CI 10.33-32.33, P =0.03). The decrease in the geometric mean concentrations (GMCs) of nAbs was observed as 42.9% in PLWH after peak level, which decreased from 8.07 BAU/mL [95% CI: 5.67-11.48] on Day 70 to 4.61 BAU/mL [95% CI: 3.35-6.34] on Day 190 (p = 0.02). On Day 190, only seven (18%, [95% CI: 6-40]) HNC and five (11%, [95% CI: 4-25]) PLWH maintained positive nAbs response respectively. The geometric mean ELISA units (GMEUs) and positive seroconversion rate of IgG in PLWH dropped significantly from Day 70 (GMEUs, 0.20 EU/mL, [95% CI: 0.13-0.34]; seroconversion, 52%, [95% CI: 34-69]) to Day 190 (GMEUs, 0.05 EU/mL, [95% CI: 0.03-0.08], P<0.001; seroconversion, 18%, [95% CI: 8-33], P<0.001). There was no significant difference in levels and seroconversion rates of nAbs and IgG between the two groups on Day 190. The peak immunogenicity of the inactivated COVID-19 vaccine was delayed and inferior in PLWH compared to HNC, while no significant difference was found in six-month immunogenicity between the two groups. [ABSTRACT FROM AUTHOR]

Background: Human adenoviruses (HAdVs) frequently cause common respiratory or gastrointestinal infections among children, adults, individuals with immune deficiencies, and other vulnerable populations with varying degree of symptoms, ranging from mild to server, and in some cases, even fatalities. Despite the significant clinical impact of HAdVs, there is currently no approved vaccine available. Methods: This study explores the potential of the adenovirus type 5 fiber knob (Ad5-FK) to stimulate the production of Ad-specific neutralizing antibodies and T-cell responses in mice. Based on structure predictions, we first expressed Ad5-FK in E. coli and confirmed the assembly of FK into its trimeric form. After testing the binding capability of the trimeric FK to susceptible cells, the immunogenicity of the protein in combination with the c-di-AMP adjuvant was assessed in BALB/c mice. Results: The purified Ad5-FK exhibited self-trimerization and maintained correct conformation akin to the authentic FK structure. This facilitated effective binding to susceptible HEK293 cells. Notably, the protein demonstrated significant inhibition of HEK293 cells infection by rAd5-GFP. Immunization of BALB/c mice with Ad5-FK, or Ad5-FK mixed with c-di-AMP yielded FK-specific antibodies with potent neutralization capacity. Significantly, Ad5-FK was found to elicit a vigorous CD4+ T-cell response in the immunized mice. Conclusion: Our findings underscore the efficacy of FK-based vaccine in eliciting anti-Ad humoral immune response and CD4 T-cell immune reactions essential for protection against viral infections. [ABSTRACT FROM AUTHOR]

Background: Botulinum toxin type A is widely utilized for both therapeutic and aesthetic purposes, yet concerns regarding its immunogenicity have raised issues related to treatment failure and adverse reactions. Objective: This review aims to evaluate the immunogenicity of commercially available botulinum toxin type A products across various clinical indications and identify the risk factors associated with antibody formation. Methods: A comprehensive search of electronic databases was conducted to find studies that investigated the immunogenicity of botulinum toxin type A in patients treated for different conditions. The studies were classified based on the Oxford Center for Evidence-Based Medicine's evidence hierarchy. Results: The overall incidence of neutralizing antibody formation with botulinum toxin type A treatment is relatively low. However, it varies depending on the indication and is influenced by factors such as the frequency of injections and the cumulative dose. The total cumulative dose and the number of treatment cycles are critical factors in determining the risk of developing antibodies against botulinum toxin type A. Conclusion: This literature review highlights that the immunogenicity of botulinum toxin type A products differs across indications, with repeated injections posing a significant risk for the formation of neutralizing antibodies. The findings underscore the need for further research to better understand antibody formation mechanisms and to develop strategies that minimize their impact on treatment efficacy. [ABSTRACT FROM AUTHOR]

COVID-19 remains a significant threat, particularly to vulnerable populations. The emergence of new variants necessitates the development of treatments and vaccines that induce both humoral and cellular immunity. This study aimed to identify potentially immunogenic SARS-CoV-2 peptides and to explore the intricate host–pathogen interactions involving peripheral immune responses, memory profiles, and various demographic, clinical, and lifestyle factors. Using in silico and experimental methods, we identified several CD8-restricted SARS-CoV-2 peptides that are either poorly studied or have previously unreported immunogenicity: fifteen from the Spike and three each from non-structural proteins Nsp1-2-3-16. A Spike peptide, LA-9, demonstrated a 57% response rate in ELISpot assays using PBMCs from 14 HLA-A*02:01 positive, vaccinated, and mild-COVID-19 recovered subjects, indicating its potential for diagnostics, research, and multi-epitope vaccine platforms. We also found that younger individuals, with fewer vaccine doses and longer intervals since infection, showed lower anti-Spike (ELISA) and anti-Wuhan neutralizing antibodies (pseudovirus assay), higher naïve T cells, and lower central memory, effector memory, and CD4hiCD8low T cells (flow cytometry) compared to older subjects. In our cohort, a higher prevalence of Vδ2-γδ and DN T cells, and fewer naïve CD8 T cells, seemed to correlate with strong cellular and lower anti-NP antibody responses and to associate with Omicron infection, absence of confusional state, and habitual sporting activity. [ABSTRACT FROM AUTHOR]

Ricin is a highly potent toxin that has been used in various attempts at bioterrorism worldwide. Although a vaccine for preventing ricin poisoning (RiVax™) is in clinical development, there are currently no commercially available prophylaxis or treatments for ricin intoxication. Numerous studies have highlighted the potential of passive immunotherapy using anti-ricin monoclonal antibodies (mAbs) and have shown promising results in preclinical models. In this article, we describe the neutralizing and protective efficacy of a new generation of high-affinity anti-ricin mAbs, which bind and neutralize very efficiently both ricin isoforms D and E in vitro through cytotoxicity cell assays. In vivo, protection assay revealed that one of these mAbs (RicE5) conferred over 90% survival in a murine model challenged intranasally with a 5 LD50 of ricin and treated by intravenous administration of the mAbs 6 h post-intoxication. Notably, a 35% survival rate was observed even when treatment was administered 24 h post-exposure. Moreover, all surviving mice exhibited long-term immunity to high ricin doses. These findings offer promising results for the clinical development of a therapeutic candidate against ricin intoxication and may also pave the way for novel vaccination strategies against ricin or other toxins. [ABSTRACT FROM AUTHOR]

Nipah virus (NiV) is a highly pathogenic paramyxovirus capable of causing severe respiratory and neurologic disease in humans. Currently, there are no licensed vaccines or therapeutics against NiV, underscoring the urgent need for the development of countermeasures. The NiV surface-displayed glycoproteins, NiV-G and NiV-F, mediate host cell attachment and fusion, respectively, and are heavily targeted by host antibodies. Here, we describe a vaccination-derived neutralizing monoclonal antibody, mAb92, that targets NiV-F. Structural characterization of the Fab region bound to NiV-F (NiV-F-Fab92) by cryo-electron microscopy analysis reveals an epitope in the DIII domain at the membrane distal apex of NiV-F, an established site of vulnerability on the NiV surface. Further, prophylactic treatment of hamsters with mAb92 offered complete protection from NiV disease, demonstrating beneficial activity of mAb92 in vivo. This work provides support for targeting NiV-F in the development of vaccines and therapeutics against NiV. [ABSTRACT FROM AUTHOR]

Numerous gene therapy drugs for cancer have received global approval, yet their efficacy against solid tumors remains inadequate. Our previous research indicated that the fiber protein, a component of the adenovirus capsid, can propagate from infected cells to neighboring cells that express the adenovirus receptor. We hypothesize that merging this fiber protein with an anti-cancer protein could enable the anti-cancer protein to disseminate around the transfected cells, presenting a novel approach to cancer gene therapy. In our study, we discovered that the knob region of the adenovirus type 5 fiber protein is the smallest unit capable of spreading to adjacent cells in a receptor-specific manner. We also showed that the recombinant knob protein infiltrates cells after dispersing to surrounding cells. To assess the potential of the knob protein to augment gene therapy for solid tumors in mice, we expressed a fusion gene of the A subunit of cytotoxic cholera toxin and the knob region in mouse tumors. We found that this fusion protein only inhibited tumor growth in receptor-expressing mouse melanomas, and this inhibitory effect persisted even in mice with anti-knob antibodies. Our study's findings propose a novel cancer gene therapy strategy that enhances therapeutic effects by specifically delivering therapeutic proteins, expressed from in vivo administered genes, to target molecules. This outcome offers a fresh perspective on gene therapy for solid cancers, and we anticipate that knob proteins will serve as a platform for this method. [ABSTRACT FROM AUTHOR]

Background: This study aimed to support the end-of-shelf life specification (2.5 × 1010 virus particles [vp]) for the standard Ad26.COV2.S dose (5 × 1010 vp). Methods: This randomized, double-blind Phase 3 study evaluated immunogenicity, reactogenicity, and safety of several Ad26.COV2.S dose levels (range 1.25 to 9 × 1010 vp) in 1593 adults between June 2021 and July 2023. Results: Spike-binding antibody responses 28 days post-dose 1 were non-inferior for the 9 × 1010 vp, but not the 2.5 × 1010 vp group when compared with the standard dose. Non-inferiority was demonstrated in terms of spike-binding antibody responses 14 days post-dose 2 for each dose level, including the lowest dose level of 1.25 × 1010 vp, compared to 28 days after one dose and 14 days after two doses of the standard dose. Spike-binding antibody levels correlated well with virus neutralizing titers. There was no impact of pre-existing Ad26.COV2.S neutralizing titers on immunogenicity at any dose level. All dose levels were well tolerated. Conclusions: This study highlights the challenges associated with conducting clinical studies in a rapidly evolving environment and underscores the importance of platform data that can guide initial vaccine specifications such as shelf life during accelerated vaccine development. The present study supports the end-of-shelf life specifications for the approved Ad26.COV2.S dose, and could provide useful information in future vaccine developments using adenovirus vector vaccines. [ABSTRACT FROM AUTHOR]

Background: Adalimumab induces the production of anti-drug antibodies (ADA) that may lead to reduced drug concentration and loss-of-response, posing significant clinical challenges. However, traditional immunoassays have limitations in terms of sensitivity and drug-tolerance, hindering the insights of ADA response. Methods: Herein, we developed an integrated immunoassay platform combining the electrochemiluminescence immunoassay with immunomagnetic separation strategy. A longitudinal cohort study involving 49 patients with ankylosing spondylitis was carried out to analyze the dynamic profiles of ADA and to investigate the impact of ADA on adalimumab pharmacokinetics using a population pharmacokinetic model. Additionally, cross-sectional data from 12 patients were collected to validate the correlation between ADA levels and disease relapse. Results: The ADA assay demonstrated high sensitivity (0.4 ng/mL) and drugtolerance (100 mg/mL), while the neutralizing antibodies (NAB) assay showed a sensitivity of 100 ng/mL and drug-tolerance of 20 mg/mL. Analysis of the longitudinal cohort revealed that a majority of patients (44/49, 90%) developed persistent ADA within the first 24 weeks of treatment. ADA levels tended to plateau over time after an initial increase during the early immune response phase. Further, nearly all of the tested patients (26/27, 96%) were classified as NAB positive, with a strong correlation between ADA levels and neutralization capacity (R2 = 0.83, P < 0.001). Population pharmacokinetic modeling revealed a significant positive association between model-estimated individual clearance and observed ADA levels. Higher ADA levels were associated with adalimumab clearance and disease relapse in a cross-sectional cohort, suggesting a promising ADA threshold of 10 for potential clinical application. Moreover, the IgG class was the primary contributor to ADA against adalimumab and the apparent affinity exhibited an increasing trend over time, indicating a T-cell dependent mechanism for ADA elicitation by adalimumab. Conclusion: In summary, this integrated immunoassay platform shows promise for in-depth analysis of ADA against biologics, offering fresh insights into immunogenicity and its clinical implications. [ABSTRACT FROM AUTHOR]

Background: Early pregnancy Zika virus (ZIKV) infection is associated with major brain damage in fetuses, leading to microcephaly in 0.6–5.0% of cases, but the underlying mechanisms remain largely unknown. Methods: To understand the kinetics of ZIKV infection during fetal development in a nonhuman primate model, four cynomolgus macaque fetuses were exposed in utero through echo-guided intramuscular inoculation with 103 PFU of ZIKV at 70–80 days of gestation, 2 controls were mock inoculated. Clinical, immuno-virological and ultrasound imaging follow-ups of the mother/fetus pairs were performed until autopsy after cesarean section 1 or 2 months after exposure (n = 3 per group). Results: ZIKV was transmitted from the fetus to the mother and then replicate in the peripheral blood of the mother from week 1 to 4 postexposure. Infected fetal brains tended to be smaller than those of controls, but not the femur lengths. High level of viral RNA ws found after the first month in brain tissues and placenta. Thereafter, there was partial control of the virus in the fetus, resulting in a decreased number of infected tissue sections and a decreased viral load. Immune cellular and humoral responses were effectively induced. Conclusions: ZIKV infection during the second trimester of gestation induces short-term brain injury, and although viral genomes persist in tissues, most of the virus is cleared before delivery. [ABSTRACT FROM AUTHOR]

Background: Dengue is a global public health challenge which requires accurate diagnostic methods for surveillance and control. The gold standard for detecting dengue neutralizing antibodies (nAbs) is the plaque reduction neutralization test (PRNT), which is both labor-intensive and time-consuming. This study aims to evaluate three alternative approaches, namely, the MTT-based (or (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) microneutralization assay, the xCELLigence real-time cell analysis (RTCA), and the immuno-plaque assay-focus reduction neutralization test (iPA-FRNT). Methods: Twenty-two residual serum samples were tested for DENV-2 nAbs using all four assays at three neutralization endpoints of 50%, 70% and 90% inhibition in virus growth. For each neutralization endpoint, results were compared using linear regression and correlation analyses. Test performance characteristics were further obtained for iPA-FRNT using 38 additional serum samples. Results: Positive correlation of DENV-2 neutralization titers for the MTT-based microneutralization assay and the PRNT assay was only observed at the neutralization endpoint of 50% (r = 0.690). In contrast, at all three neutralization end points, a linear trend and positive correlation of DENV-2 neutralization titers for the xCELLigence RTCA and the PRNT assays were observed, yielding strong or very strong correlation (r = 0.829 to 0.967). This was similarly observed for the iPA-FRNT assay (r = 0.821 to 0.916), which also offered the added advantage of measuring neutralizing titers to non-plaque forming viruses. Conclusion: The xCELLigence RTCA and iPA-FRNT assays could serve as suitable alternatives to PRNT for dengue serological testing. The decision to adopt these methods may depend on the laboratory setting, and the utility of additional applications offered by these technologies. [ABSTRACT FROM AUTHOR]

Leukemia inhibitory factor (LIF) is involved in the progression of different cancers. In this study, we investigated the effect of anti-LIF antibodies on immune-related gene expression in the Balb/c mouse model of breast cancer. To immunize mice against LIF, recombinant LIF with Freund adjuvant was injected into the test group, whereas the control group received phosphate-buffered saline with adjuvant. Tumor induction (4T1 cell line) was performed by increasing the antibody titer. The expression of immune-related genes was evaluated by real-time PCR. The anti-LIF titer was significantly increased in the immunized group. The expression of genes related to the differentiation of T helper (Th)-1, Th-2, and Th-17 cells was significantly higher in the immunized group than in the control group. In addition, anti-LIF did not have a significant effect on the expression of genes related to the differentiation of regulatory T cells, and immune checkpoint-associated genes. Additionally, the test group had higher survival and lower tumor development rates. The results demonstrated that the anti-LIF antibody may potentially play a role in the differentiation of immune cells or immune responses. However, further studies utilizing advanced techniques are necessary to validate its function. [ABSTRACT FROM AUTHOR]

Background: Porcine Epidemic Diarrhea (PED) is a highly contagious disease caused by Porcine Epidemic Diarrhea Virus (PEDV), resulting in a mortality rate of suckling piglets as high as 100%. Vaccination is the primary strategy for controlling PEDV infection, however, there is currently a lack of reliable methods for assessing the efficacy of vaccination. This study aimed to analyze serum and colostrum samples from 75 parturient sows with a specific vaccination strategy to measure levels of IgG, IgA, and neutralizing antibodies (nAbs) against PEDV, and to investigate the correlation between serum and colostrum antibody levels, as well as to identify potential biomarkers that can be used to evaluate immunization effects under field conditions. Results: The findings of correlation analysis between antibody levels of IgA, IgG, and nAbs in serum or colostrum samples revealed that IgG demonstrated the most robust correlation with nAbs exhibiting a correlation coefficient of 0.64 in serum samples. Conversely, IgA exhibited the highest correlation with nAbs, with a correlation coefficient of 0.47 in colostrum samples. Additionally, the correlation analysis of antibody levels between serum and colostrum samples indicated that serum IgA displayed the strongest correlation with colostrum IgA, with a coefficient of 0.63, indicating that serum IgA may serve as a viable alternative indicator for evaluating IgA levels in colostrum samples. To further evaluate the suitability of serum IgA as a substitute marker for colostrum IgA, levels of IgA antibodies in serum samples from sows were examined both pre- and post-parturition. The findings indicated that serum IgA levels were initially low prior to the initial immunization, experienced a notable rise 21 days after immunization, and maintained a significant elevation compared to pre-immunization levels from 21 days pre-parturition to 14 days postpartum, spanning a total of 35 days. Conclusions: Serum anti-PEDV IgA antibody levels may serve as a valuable predictor for immunization effects, allowing for the assessment of colostrum IgA antibody levels up to 21 days in advance. This insight could enable veterinarians to timely adjust or optimize immunization strategies prior to parturition, thereby ensuring adequate passive immunity is conferred to piglets through colostral transfer postpartum. [ABSTRACT FROM AUTHOR]

The global pandemic sparked by the emergence of SARS-CoV-2 and its variants has imposed a substantial burden of morbidity and mortality. Central to the battle against these viral threats is the immune response, with a spotlight on the pivotal role played by neutralizing antibodies. This comprehensive review delves into current research, unravelling the dual functionality of neutralizing antibodies acting as formidable barriers to viral replication and crucial facilitators of adaptive immune memory. Beyond this dual purpose, the review illuminates the nuanced variability characterizing neutralizing antibody responses to SARS-CoV-2. Emphasizing the dynamic nature of these responses, the review advocates for the plausible challenges in targeted therapeutic interventions. This review also attempts to compare various vaccination approaches and their impact on SARS-CoV-2, as well as offer insights into various Omicron variations. Recognizing the ever-evolving viral landscape, this exploration underscores the necessity of flexible approaches to address the diverse challenges posed by SARS-CoV-2 and its variants, contributing valuable insights to the ongoing global efforts in pandemic mitigation and public health safeguarding. [ABSTRACT FROM AUTHOR]

Over the past three years, new SARS-CoV-2 variants have continuously emerged, evolving to a point where an immune response against the original vaccine no longer provided optimal protection against these new strains. During this time, high-throughput neutralization assays based on pseudoviruses have become a valuable tool for assessing the efficacy of new vaccines, screening updated vaccine candidates against emerging variants, and testing the efficacy of new therapeutics such as monoclonal antibodies. Lentiviral vectors derived from HIV-1 are popular for developing pseudo and chimeric viruses due to their ease of use, stability, and long-term transgene expression. However, the HIV-based platform has lower transduction rates for pseudotyping coronavirus spike proteins than other pseudovirus platforms, necessitating more optimized methods. As the SARS-CoV-2 virus evolved, we produced over 18 variants of the spike protein for pseudotyping with an HIV-based vector, optimizing experimental parameters for their production and transduction. In this article, we present key parameters that were assessed to improve such technology, including (a) the timing and method of collection of pseudovirus supernatant; (b) the timing of host cell transduction; (c) cell culture media replenishment after pseudovirus adsorption; and (d) the centrifugation (spinoculation) parameters of the host cell+ pseudovirus mix, towards improved transduction. Additionally, we found that, for some pseudoviruses, the addition of a cationic polymer (polybrene) to the culture medium improved the transduction process. These findings were applicable across variant spike pseudoviruses that include not only SARS-CoV-2 variants, but also SARS, MERS, Alpha Coronavirus (NL-63), and bat-like coronaviruses. In summary, we present improvements in transduction efficiency, which can broaden the dynamic range of the pseudovirus titration and neutralization assays. [ABSTRACT FROM AUTHOR]

Virus-like particles (VLPs) are non-infectious and serve as promising vaccine platforms because they mimic the membrane-embedded conformations of fusion glycoproteins on native viruses. Here, we employed SARS-CoV-2 VLPs (SMEN) presenting ancestral, Beta, or Omicron spikes to identify the variant spike that elicits potent and cross-protective immune responses in the highly sensitive K18-hACE2 challenge mouse model. A combined intranasal and intramuscular SMEN vaccine regimen generated the most effective immune responses to significantly reduce disease burden. Protection was primarily mediated by antibodies, with minor but distinct contributions from T cells in reducing virus spread and inflammation. Immunization with SMEN carrying ancestral spike resulted in 100, 75, or 0% protection against ancestral, Delta, or Beta variant-induced mortality, respectively. However, SMEN with an Omicron spike provided only limited protection against ancestral (50%), Delta (0%), and Beta (25%) challenges. By contrast, SMEN with Beta spikes offered 100% protection against the variants used in this study. Thus, the Beta variant not only overcame the immunity produced by other variants, but the Beta spike also elicited diverse and effective humoral immune responses. Our findings suggest that leveraging the Beta variant spike protein can enhance SARS-CoV-2 immunity, potentially leading to a more comprehensive vaccine against emerging variants. [ABSTRACT FROM AUTHOR]

Bourbon virus is a tickborne virus that can cause human disease. Cases have been reported in Kansas, Oklahoma, and Missouri, USA. We identified Bourbon virus–specific neutralizing antibodies in patients from North Carolina. Bourbon virus infections are likely more common than previously thought, highlighting the need for improved diagnostics and surveillance.

In order to clarify the pre-exist immunity background of different human coronaviruses (HCoV), this study investigated the positive rate of spike (S) protein antibodies of HCoV, including HCoV- severe acute respiratory syndrome (SARS) −associated coronavirus (SARS-CoV-1), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Middle East respiratory syndrome coronavirus (MERS-CoV), HCoV-229E, HCoV-NL63, HCoV-HKU1 and HCoV-OC43, before and after the Coronavirus Disease 2019 (COVID-19) outbreak. We utilized pseudotyped virus-based neutralization assays (PBNA) or enzyme-linked immunosorbent assays (ELISA) to detect antibody levels against HCoV in serum samples collected in 2009–2010 and 2023. The PBNA results showed that neutralizing antibodies against SARS-CoV-1 and the MERS-CoV were negative. In the serum samples from 2009 to 2010, neutralizing antibodies against SARS-CoV-2 (D614G) were negative, whereas in the serum samples from 2023, 73 samples (73 %) showed neutralizing reactions with the SARS-CoV-2 D614G strain, 96 samples (96 %) with the BA.5 strain, and 91 samples (91 %) with the BF.7 strain. Among pre-COVID-19 samples, 33 % (33/100) showed neutralizing reactions with HCoV-229E and 63 % (63/100) with HCoV-NL63. Among post-COVID-19 samples, 50 % (50/100) showed neutralizing reactions with HCoV-229E and 49 % (49/100) with HCoV-NL63. Due to the different receptors of alpha coronavirus genus compared to other beta coronavirus genus, neutralizing antibodies against HCoV-OC43 and HCoV-HKU1 virus cannot be detected by constructing corresponding pseudotyped virus. Binding antibodies against HCoV-OC43 and HCoV-HKU1 virus were detected using ELISA. The results revealed that among pre-COVID-19 samples, 83 % (83/100) and 45 % (45/100) had binding activity with HCoV-OC43 and HCoV-HKU1, respectively. Among post-COVID-19 samples, 100 % (100/100) and 81 % (81/100) had binding activity with HCoV-OC43 and HCoV-HKU1, respectively.

Abstract Background Human adenoviruses (HAdVs) frequently cause common respiratory or gastrointestinal infections among children, adults, individuals with immune deficiencies, and other vulnerable populations with varying degree of symptoms, ranging from mild to server, and in some cases, even fatalities. Despite the significant clinical impact of HAdVs, there is currently no approved vaccine available. Methods This study explores the potential of the adenovirus type 5 fiber knob (Ad5-FK) to stimulate the production of Ad-specific neutralizing antibodies and T-cell responses in mice. Based on structure predictions, we first expressed Ad5-FK in E. coli and confirmed the assembly of FK into its trimeric form. After testing the binding capability of the trimeric FK to susceptible cells, the immunogenicity of the protein in combination with the c-di-AMP adjuvant was assessed in BALB/c mice. Results The purified Ad5-FK exhibited self-trimerization and maintained correct conformation akin to the authentic FK structure. This facilitated effective binding to susceptible HEK293 cells. Notably, the protein demonstrated significant inhibition of HEK293 cells infection by rAd5-GFP. Immunization of BALB/c mice with Ad5-FK, or Ad5-FK mixed with c-di-AMP yielded FK-specific antibodies with potent neutralization capacity. Significantly, Ad5-FK was found to elicit a vigorous CD4+ T-cell response in the immunized mice. Conclusion Our findings underscore the efficacy of FK-based vaccine in eliciting anti-Ad humoral immune response and CD4 T-cell immune reactions essential for protection against viral infections.

Introduction: This study was conducted to determine total and neutralizing antibody (nAb) titer in individuals at an interval of 2 and 6 months after primary vaccination and after 1 month after administration of booster dose. MATERIALS AND METHODS: A serum sample was collected from 72 volunteers who were vaccinated with either the Covishield or CovaxinTM vaccine for quantitative estimation of human anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike immunoglobulin G (IgG) antibodies and nAb. nAb against SARS-CoV-2 was detected by GenScript (New Jersey, USA) and was quantitatively estimated by in-house developed enzyme-linked immunosorbent assay (ELISA). Results: Out of 72 study participants, 62.5% and 37.5% were male and female, respectively, and were in the age group of 21–83 years. About 94.44% of study volunteers were vaccinated with the CovishieldTM vaccine. Diabetes mellitus and hypertension were observed in 7.5% of volunteers. The average time interval between two doses of study vaccination was 37 days. Sixty-seven (93.18%), 50 (69.3%), and 69 (96.8%) (N = 72) volunteers elicited good nAb response at the end of 2 months, 6 months, and 1 month post-booster dose vaccination, respectively. Conclusion: Rapid nAb reaction to Spike protein development correlates with viral immunity for Covishield vaccine recipients. Due to the availability of limited data for the CovaxinTM vaccine, we are unable to compare the effectiveness of the two vaccinations, and we are also unable to analyze the vaccine’s efficacy.

Botulism is an acute infectious disease caused by a neutrotoxin produced by the bacterium Clostridium botulinum and characterized by severe bulbar lesions. Botulism is characterized by the complexity of diagnosis and in adverse cases can lead to death. At the moment, in the complex therapy of botulism, the introduction of a mixture of antitoxic serums is mandatory. In addition to specific treatment, pathogenetic therapy is performed for all patients. Specific prophylaxis is carried out with polyanatoxin to a narrow group of people in contact with Clostridium botulinum or their toxins. However, neutralizing anti-botulinum antibodies may be detected in the blood serum of a number of individuals, which have a protective effect when encountering an infection. This article presents a clinical case of severe botulism in an adult patient with simultaneous absence of symptoms of the disease in family members.Botulinum toxin preparations have long been used in aesthetic medicine. It is worth noting that the botulinum toxin molecule has a high molecular weight and can cause an immune response with repeated injections, especially in areas rich in lymph nodes. Forming specific antibodies belong to the IgG class and may have neutralizing properties. In the above clinical case, the patient’s wife, during repeated injections of botulinum toxin, most likely, the formation of neutralizing antibodies occurred, which, in turn, protected the woman from the disease.

Abstract Background Viral neutralization (NT) assays can be used to determine the immune status of patients or assess the potency of candidate vaccines or therapeutic monoclonal antibodies (mAbs). Focus reduction neutralization test (FRNT) is a conventional neutralization test (cVNT) with superior specificity for measurement of neutralizing antibodies against a specific virus. Unfortunately, the application of FRNT to the chikungunya virus (CHIKV) involves a highly pathogenic bio-agent requiring biosafety level 3 (BSL3) facilities, which inevitably imposes high costs and limits accessibility. In this study, we evaluated a safe surrogate virus neutralization test (sVNT) that uses novel CHIKV replicon particles (VRPs) expressing eGFP and luciferase (Luc) to enable the rapid detection and quantification of neutralizing activity in clinical human serum samples. Methods This unmatched case-control validation study used serum samples from laboratory-confirmed cases of CHIKV (n = 19), dengue virus (DENV; n = 9), Japanese encephalitis virus (JEV; n = 5), and normal individuals (n = 20). We evaluated the effectiveness of sVNT, based on mosquito cell-derived CHIK VRPs (mos-CHIK VRPs), in detecting (eGFP) and quantifying (Luc) neutralizing activity, considering specificity, sensitivity, and reproducibility. We conducted correlation analysis between the proposed rapid method (20 h) versus FRNT assay (72 h). We also investigated the correlation between sVNT and FRNT in NT titrations in terms of Pearson’s correlation coefficient (r) and sigmoidal curve fitting. Results In NT screening assays, sVNT-eGFP screening achieved sensitivity and specificity of 100%. In quantitative neutralization assays, we observed a Pearson’s correlation coefficient of 0.83 for NT50 values between sVNT-Luc and FRNT. Conclusions Facile VRP-based sVNT within 24 h proved highly reliable in the identification and quantification of neutralizing activity against CHIKV in clinical serum samples.

The global pandemic sparked by the emergence of SARS-CoV-2 and its variants has imposed a substantial burden of morbidity and mortality. Central to the battle against these viral threats is the immune response, with a spotlight on the pivotal role played by neutralizing antibodies. This comprehensive review delves into current research, unravelling the dual functionality of neutralizing antibodies acting as formidable barriers to viral replication and crucial facilitators of adaptive immune memory. Beyond this dual purpose, the review illuminates the nuanced variability characterizing neutralizing antibody responses to SARS-CoV-2. Emphasizing the dynamic nature of these responses, the review advocates for the plausible challenges in targeted therapeutic interventions. This review also attempts to compare various vaccination approaches and their impact on SARS-CoV-2, as well as offer insights into various Omicron variations. Recognizing the ever-evolving viral landscape, this exploration underscores the necessity of flexible approaches to address the diverse challenges posed by SARS-CoV-2 and its variants, contributing valuable insights to the ongoing global efforts in pandemic mitigation and public health safeguarding.

Abstract Background Dengue is a global public health challenge which requires accurate diagnostic methods for surveillance and control. The gold standard for detecting dengue neutralizing antibodies (nAbs) is the plaque reduction neutralization test (PRNT), which is both labor-intensive and time-consuming. This study aims to evaluate three alternative approaches, namely, the MTT-based (or (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) microneutralization assay, the xCELLigence real-time cell analysis (RTCA), and the immuno-plaque assay-focus reduction neutralization test (iPA-FRNT). Methods Twenty-two residual serum samples were tested for DENV-2 nAbs using all four assays at three neutralization endpoints of 50%, 70% and 90% inhibition in virus growth. For each neutralization endpoint, results were compared using linear regression and correlation analyses. Test performance characteristics were further obtained for iPA-FRNT using 38 additional serum samples. Results Positive correlation of DENV-2 neutralization titers for the MTT-based microneutralization assay and the PRNT assay was only observed at the neutralization endpoint of 50% (r = 0.690). In contrast, at all three neutralization end points, a linear trend and positive correlation of DENV-2 neutralization titers for the xCELLigence RTCA and the PRNT assays were observed, yielding strong or very strong correlation (r = 0.829 to 0.967). This was similarly observed for the iPA-FRNT assay (r = 0.821 to 0.916), which also offered the added advantage of measuring neutralizing titers to non-plaque forming viruses. Conclusion The xCELLigence RTCA and iPA-FRNT assays could serve as suitable alternatives to PRNT for dengue serological testing. The decision to adopt these methods may depend on the laboratory setting, and the utility of additional applications offered by these technologies.

Abstract Background Early pregnancy Zika virus (ZIKV) infection is associated with major brain damage in fetuses, leading to microcephaly in 0.6–5.0% of cases, but the underlying mechanisms remain largely unknown. Methods To understand the kinetics of ZIKV infection during fetal development in a nonhuman primate model, four cynomolgus macaque fetuses were exposed in utero through echo-guided intramuscular inoculation with 103 PFU of ZIKV at 70–80 days of gestation, 2 controls were mock inoculated. Clinical, immuno-virological and ultrasound imaging follow-ups of the mother/fetus pairs were performed until autopsy after cesarean section 1 or 2 months after exposure (n = 3 per group). Results ZIKV was transmitted from the fetus to the mother and then replicate in the peripheral blood of the mother from week 1 to 4 postexposure. Infected fetal brains tended to be smaller than those of controls, but not the femur lengths. High level of viral RNA ws found after the first month in brain tissues and placenta. Thereafter, there was partial control of the virus in the fetus, resulting in a decreased number of infected tissue sections and a decreased viral load. Immune cellular and humoral responses were effectively induced. Conclusions ZIKV infection during the second trimester of gestation induces short-term brain injury, and although viral genomes persist in tissues, most of the virus is cleared before delivery.

Abstract Leukemia inhibitory factor (LIF) is involved in the progression of different cancers. In this study, we investigated the effect of anti-LIF antibodies on immune-related gene expression in the Balb/c mouse model of breast cancer. To immunize mice against LIF, recombinant LIF with Freund adjuvant was injected into the test group, whereas the control group received phosphate-buffered saline with adjuvant. Tumor induction (4T1 cell line) was performed by increasing the antibody titer. The expression of immune-related genes was evaluated by real-time PCR. The anti-LIF titer was significantly increased in the immunized group. The expression of genes related to the differentiation of T helper (Th)-1, Th-2, and Th-17 cells was significantly higher in the immunized group than in the control group. In addition, anti-LIF did not have a significant effect on the expression of genes related to the differentiation of regulatory T cells, and immune checkpoint-associated genes. Additionally, the test group had higher survival and lower tumor development rates. The results demonstrated that the anti-LIF antibody may potentially play a role in the differentiation of immune cells or immune responses. However, further studies utilizing advanced techniques are necessary to validate its function.

Abstract Background Porcine Epidemic Diarrhea (PED) is a highly contagious disease caused by Porcine Epidemic Diarrhea Virus (PEDV), resulting in a mortality rate of suckling piglets as high as 100%. Vaccination is the primary strategy for controlling PEDV infection, however, there is currently a lack of reliable methods for assessing the efficacy of vaccination. This study aimed to analyze serum and colostrum samples from 75 parturient sows with a specific vaccination strategy to measure levels of IgG, IgA, and neutralizing antibodies (nAbs) against PEDV, and to investigate the correlation between serum and colostrum antibody levels, as well as to identify potential biomarkers that can be used to evaluate immunization effects under field conditions. Results The findings of correlation analysis between antibody levels of IgA, IgG, and nAbs in serum or colostrum samples revealed that IgG demonstrated the most robust correlation with nAbs exhibiting a correlation coefficient of 0.64 in serum samples. Conversely, IgA exhibited the highest correlation with nAbs, with a correlation coefficient of 0.47 in colostrum samples. Additionally, the correlation analysis of antibody levels between serum and colostrum samples indicated that serum IgA displayed the strongest correlation with colostrum IgA, with a coefficient of 0.63, indicating that serum IgA may serve as a viable alternative indicator for evaluating IgA levels in colostrum samples. To further evaluate the suitability of serum IgA as a substitute marker for colostrum IgA, levels of IgA antibodies in serum samples from sows were examined both pre- and post-parturition. The findings indicated that serum IgA levels were initially low prior to the initial immunization, experienced a notable rise 21 days after immunization, and maintained a significant elevation compared to pre-immunization levels from 21 days pre-parturition to 14 days postpartum, spanning a total of 35 days. Conclusions Serum anti-PEDV IgA antibody levels may serve as a valuable predictor for immunization effects, allowing for the assessment of colostrum IgA antibody levels up to 21 days in advance. This insight could enable veterinarians to timely adjust or optimize immunization strategies prior to parturition, thereby ensuring adequate passive immunity is conferred to piglets through colostral transfer postpartum.

Summary: Background and Aims: Passive transfer of antibodies through breastfeeding is a potential mode of protection for newborns and infants following maternal SARS-CoV-2 infection. The primary goal of this study was to evaluate and characterize SARS-CoV-2 Spike (S)-specific antibodies in human milk samples collected longitudinally from a cohort of convalescent mothers. Methods: SARS-CoV-2 infected participants enrolled in this study were lactating women aged 29–36 years with a confirmed COVID-19 diagnosis who donated milk samples at intervals over the six-month study period. Samples were evaluated for antibody subclass SARS-Cov-2 S glycoprotein binding activity by ELISA, and for the capacity of antibodies purified from these samples to mediate neutralizing antibody (nAb) activity in S pseudovirus inhibition assays and phagocytic activity in an antibody-dependent phagocytosis assay. Results: Robust S-reactive IgM, IgG and IgA ELISA titers were found at day 7 after enrollment, with IgG and IgA levels persisting through 6 months. The majority of S-reactive IgA in milk was secretory in nature. Strong IgG (mean IC50 value 29.19μg/ml) and IgA (mean IC50 value 10.17μg/ml) nAb activity was found in all convalescent samples at 14 days with a decline by 3 months after the onset of symptoms but was not seen in pre-pandemic controls. Both IgG and IgA antibodies mediated phagocytic activity in samples from all subjects by day 14 after the onset of symptoms. Conclusions: Our findings indicate that human milk from SARS-CoV-2 infected mothers have the capacity to transfer SARS-CoV-2-specific antibodies capable of mediating multiple functional activities to newborns via breastfeeding.

ABSTRACTIntroduction Pseudoviruses are recombinant, replication-incompetent, viral particles designed to mimic the surface characteristics of native enveloped viruses. They are a safer, and cost-effective research alternative to live viruses. With the potential emergence of the next major infectious disease, more vaccine scientists must become familiar with the pseudovirus platform as a vaccine development tool to mitigate future outbreaks.Areas Covered This review aims at vaccine developers to provide a basic understanding of pseudoviruses, list their production methods, and discuss their utility to assess vaccine efficacy against enveloped viral pathogens. We further illustrate their usefulness as wet-lab simulators for emerging mutant variants, and new viruses to help prepare for current and future viral outbreaks, minimizing the need for gain-of-function experiments with highly infectious or lethal enveloped viruses.Expert opinion With this platform, researchers can better understand the role of virus–receptor interactions and entry in infections, prepare for dangerous mutations, and develop effective vaccines.

Introduction. Vaccination could be the most effective means of preventing hemorrhagic fever with renal syndrome (HFRS), which is one of the leading zoonoses and a major cause of natural disease in humans. Therefore, research to develop an effective vaccine and the search for new non-toxic and effective adjuvants that can enhance and prolong the immune response, reduce the antigen concentration and reduce the frequency of dose administration is an urgent task. The aim of the study was to determine the dependence of the immunogenic activity of an experimental hantavirus vaccine based on Puumala virus (HV) on the antigen dose both in native form and in combination with carbohydrate adjuvants. Materials and methods. The immunoadjuvant effect of Ac3-LPS S. sonnei and S. flexneri 1B and emulsions of nanoemulsified squalene Sepivac SWE (SWE) as part of HV at the optimal and minimal doses was investigated by induction of neutralising antibodies after 3-fold immunisation (day 0, 14, 182) of guinea pigs (Cavia porcellus). Differences in the immunogenic activity of HV were assessed in the neutralisation reaction by 50% suppression of focal units in Vero E6 cell cultures. Results. A statistically significant increase in neutralising antibodies levels was observed after immunization both with HV at the optimal dose and for its combination with adjuvants. Ac3-LPS S. sonnei and SWE showed the most pronounced immunoadjuvant effect at concentrations of 50 and 100 μg/dose, respectively. The immunoadjuvant effect of the combination of the hantavirus vaccine with Ac3-LPS S. sonnei and SWE contributed to both an enhanced immune response and its duration. The tenfold reduction of the antigen dose in the presence of SWE allows optimization of the immune response to the vaccine. Conclusion. The results of this study show the prospects of using Ac3-LPS S. sonnei and Sepivac SWE in the vaccine for the prevention of HFRS.

Abstract Oropouche and Mayaro viruses are enzootic arboviruses of public health concern throughout Latin America. Recent outbreaks of OROV in northern region and sporadic autochthonous cases in western region of Brazil, suggest a silent circulation of these neglected viruses. Aiming to investigate the exposure of different species of domestic animals to MAYV and OROV in urban and peri-urban areas of West-Central Brazil, we performed a cross-sectional serosurvey by plaque reduction neutralization test (PRNT). Our findings included neutralizing antibodies for both arboviruses in cattle, dogs and horses, suggesting eventual role of domestic animals in enzootic arbovirus surveillance in Brazil.

The recombination plays a key role in promoting evolution of RNA viruses and emergence of potentially epidemic variants. Some studies investigated the recombination occurrence among SARS-CoV-2, without exploring its impact on virus-host interaction. In the aim to investigate the burden of recombination in terms of frequency and distribution, the occurrence of recombination was first explored in 44 230 Omicron sequences among BQ subvariants and the under investigation "ML" (Multiple Lineages) denoted sequences, using 3seq software. Second, the recombination impact on interaction between the Spike protein and ACE2 receptor as well as neutralizing antibodies (nAbs), was analyzed using docking tools. Recombination was detected in 56.91% and 82.20% of BQ and ML strains, respectively. It took place mainly in spike and ORF1a genes. For BQ recombinant strains, the docking analysis showed that the spike interacted strongly with ACE2 and weakly with nAbs. The mutations S373P, S375F and T376A constitute a residue network that enhances the RBD interaction with ACE2. Thirteen mutations in RBD (S373P, S375F, T376A, D405N, R408S, K417N, N440K, S477N, P494S, Q498R, N501Y, and Y505H) and NTD (Y240H) seem to be implicated in immune evasion of recombinants by altering spike interaction with nAbs. In conclusion, this "in silico" study demonstrated that the recombination mechanism is frequent among Omicron BQ and ML variants. It highlights new key mutations, that potentially implicated in enhancement of spike binding to ACE2 (F376A) and escape from nAbs (RBD: F376A, D405N, R408S, N440K, S477N, P494S, and Y505H; NTD: Y240H). Our findings present considerable insights for the elaboration of effective prophylaxis and therapeutic strategies against future SARS-CoV-2 waves. [ABSTRACT FROM AUTHOR]

Despite the potential of neutralizing antibodies in the management of severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), clinical research on its efficacy in Chinese patients remains limited. This study is aimed at investigating the therapeutic effect of combination of antiviral therapy with neutralizing monoclonal antibodies for recurrent persistent SARS‐CoV‐2 pneumonia in patients with lymphoma complicated by B cell depletion. A prospective study was conducted on Chinese patients who were treated with antiviral nirmatrelvir/ritonavir therapy and the neutralizing antibody tixagevimab–cilgavimab (tix‐cil). The primary outcome was the rate of recurrent SARS‐CoV‐2 infection. Five patients with lymphoma experienced recurrent SARS‐CoV‐2 pneumonia and received tix‐cil treatment. All patients had a history of CD20 monoclonal antibody use within the year preceding SARS‐CoV‐2 infection, and two patients also had a history of Bruton's tyrosine kinase (BTK) inhibitor use. These patients had notably low lymphocyte counts and exhibited near depletion of B cells. All five patients tested negative for serum SARS‐CoV‐2 IgG and IgM antibodies. None of the patients developed reinfection with SARS‐CoV‐2 pneumonia after antiviral and tix‐cil treatment during the 6‐month follow‐up period. In conclusion, the administration of antiviral and SARS‐CoV‐2‐neutralizing antibodies showed encouraging therapeutic efficacy against SARS‐CoV‐2 pneumonia in patients with lymphoma complicated by B cell depletion, along with the potential preventive effect of neutralizing antibodies for up to 6 months. [ABSTRACT FROM AUTHOR]

Objective：To construct a Bandavirus davieense virus (DBV) vaccine based on the strategy of mRNA vaccine, immunize BALB/c mice, and evaluate its immunologic characteristics. Methods：The coding sequence of DBV glycoprotein Gn was optimized and synthesized, then inserted into the pGEM -3Zf (+) plasmid. The linearization plasmids were enzyme digested by BamH Ⅰ, cap and polyA tailing were added with polymerase to complete in vitro transcription. Western blotting verified the protein expression by transient transfection of the mRNA into eukaryotic 293FT cells. The mRNA was delivered by lipid nanoparticles, and immunized BALB/c mice by intramuscular injection of low (2 μg/mouse), medium (5 μg/mouse) and high (20 μg/mouse) dose once every two weeks. The antibody titer in mice serum was detected by ELISA, and the ability of antibody to neutralize DBV in vitro was detected at the cellular level by virus neutralization assay. Results：The prepared DBV mRNA vaccine could be transcribed and expressed in vitro. All three immunization doses induced high levels of specific antibodies in mice, with the high-dose immunization group inducing stable antibody expression for over 10 weeks. The virus neutralization assay showed that immune sera could bind to the virus and block virus infection of cells. Conclusion：A DBV mRNA vaccine capable of inducing specific neutralizing antibodies in mice is obtained, laying the foundation for research on the prevention of DBV infection. [ABSTRACT FROM AUTHOR]

COVID‐19 vaccine became available in Tanzania during the first wave of the Omicron variant. During that time community seroprevalence of SARS‐CoV‐2 was already at 50%–80%. To date, it remains largely unknown whether ongoing vaccination with the primary series vaccines has any meaningful immune‐boosting effects against newer Omicron subvariants. Therefore, we tested cross‐neutralizing capacity of antibodies elicited by infection, vaccination, or both against SARS‐CoV‐2 Omicron subvariants BA.1, and the newer subvariants BQ.1.1 and XBB.1.5. that were unexperienced by this population. Participants who were either SARS‐CoV‐2 infected‐only (n = 28), infected vaccinated (n = 22), or vaccinated‐only (n = 73) were recruited from Dar‐es‐Salaam, Tanzania, between April and December 2022. Plasma 50% neutralization titers (NT50) against SARS‐CoV‐2 wild‐type strain and Omicron subvariants were quantified by a lentiviral‐based pseudo‐virus assay. Percentage of participants with neutralizing activity against WT and BA.1 was high (>85%) but was reduced against BQ.1.1 (64%–77%) and XBB.1.5 (35%–68%) subvariants. The low median cross‐neutralization titer was slightly higher in the infected vaccinated group compared to vaccine‐only group against BQ.1.1 (NT50 148 vs. 85, p = 0.032) and XBB.1.5 (NT50 85 vs. 37 p = 0.022) subvariants. In contrast, vaccine‐boost among the infected vaccinated did not result to increased cross‐neutralization compared to infected‐only participants (BQ.1.1 [NT50 of 148 vs. 100, p = 0.501] and XBB.1.5 [NT50 86 vs. 45, p = 0.474]). We report severely attenuated neutralization titers against BQ.1.1 and XBB.1.5 subvariants among vaccinated participants, which marginally improved in the infected vaccinated participants. Our findings call for further studies to evaluate effectiveness of the primary series vaccines in preventing severe infection and mortality against the newer variants. [ABSTRACT FROM AUTHOR]

Patients with hematologic malignancies still face a significant risk of severe coronavirus disease 2019 (COVID-19). The severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)-neutralizing monoclonal antibody combination tixagevimab/cilgavimab (TIX/CGB) could be administered to immunocompromised patients for pre-exposure prophylaxis (PrEP) before the emergence of TIX/CGB-resistant COVID-19 Omicron variants. TIX/CGB application could be carried out regardless of the host's immune response to previous active SARS-CoV-2 vaccinations or infections. Because the efficacy of COVID-19 PrEP remains unclear, especially in SARS-CoV-2-seropositive patients, German national guidelines recommended TIX/CGB PrEP only for SARS-CoV-2-seronegative patients in addition to an intensified active vaccination schedule. Having followed these guidelines, we now report the characteristics and outcomes of 54 recipients of TIX/CGB PrEP in SARS-CoV-2-seronegative patients with hematological disease from a German tertiary medical center and compare them to 125 seropositive patients who did not receive any PrEP. While the number of patients with B-cell lymphomas was significantly higher in the seronegative cohort (33 (61%) vs. 18 (14%) cases, p < 0.01), patients with myeloid diseases were significantly more frequent in the seropositive cohort (51 (41%) vs. 5 (9%) cases, p < 0.01). Strikingly, patients who had undergone allogeneic hematopoietic stem cell transplantation were significantly more likely (forty-nine (39%) vs. six (11%) cases, p < 0.01) to be SARS-CoV-2 seropositive. We observed that prophylactic application of TIX/CGB PrEP to a highly vulnerable group of SARS-CoV-2-seronegative patients resulted in a similar number of COVID-19 breakthrough infections compared to the untreated seropositive control group (16 (32%) vs. 39 (36%), p = 0.62) and comparable COVID-19-related outcomes like hospitalization and oxygen requirement throughout an extended follow-up period of 12 months. In conclusion, our results support the tailored approach of administering TIX/CGB PrEP only to SARS-CoV-2-seronegative patients during the COVID-19 pandemic and might provide a rationale for similar strategies during future outbreaks/diseases, especially in times of initial limited availability and/or financial constraints. [ABSTRACT FROM AUTHOR]

The transplacental transmission of CSFV and the resulting persistent congenital infection in newborn piglets have been abundantly discussed in pregnant sows suffering from virus infection. Importantly, the availability of safe commercial vaccines with proven efficacy to prevent the generation of congenital and postnatal persistent infections in pregnant sows are critical tools for controlling the disease in CSF endemic areas. Here, we demonstrate the high efficacy of a single dose of the recombinant FlagT4G vaccine to provide solid protection in pregnant sows against transplacental transmission of a highly virulent CSFV. Pregnant sows vaccinated with FlagT4G at 44 days of gestation elicited a strong CSFV-specific antibody response, with neutralizing antibody levels above those required for protection against CSFV. Importantly, after the challenge with a highly virulent CSFV, all foetuses from FlagT4G-vaccinated sows lacked CSF macroscopic lesions and showed a complete absence of the challenge virus in their internal organs at day 79 of gestation. Therefore, pregnant sows safely vaccinated with FlagT4G without affecting reproductive efficacy are efficaciously protected, along with their foetuses, against the infection and disease caused by a CSFV virulent field strain. [ABSTRACT FROM AUTHOR]

COVID-19 has caused millions of deaths and many times more infections worldwide, emphasizing the unpreparedness of the global health system in the face of new infections and the key role for vaccines and therapeutics, including virus-neutralizing antibodies, in prevention and containment of the disease. Continuous evolution of the SARS-CoV-2 coronavirus has been causing its new variants to evade the action of the immune system, which highlighted the importance of detailed knowledge of the epitopes of already selected potent virus-neutralizing antibodies. A single-chain antibody ("nanobody") targeting the SARS-CoV-2 receptor-binding domain (RBD), clone P2C5, had exhibited robust virus-neutralizing activity against all SARS-CoV-2 variants and, being a major component of the anti-COVID-19 formulation "GamCoviMab", had successfully passed Phase I of clinical trials. However, after the emergence of the Delta and XBB variants, a decrease in the neutralizing activity of this nanobody was observed. Here we report on the successful crystal structure determination of the RBD:P2C5 complex at 3.1 Å, which revealed the intricate protein–protein interface, sterically occluding full ACE2 receptor binding by the P2C5-neutralized RBD. Moreover, the structure revealed the developed RBD:P2C5 interface centered around residues Leu452 and Phe490, thereby explaining the evasion of the Delta or Omicron XBB, but not Omicron B.1.1.529 variant, as a result of the single L452R or F490S mutations, respectively, from the action of P2C5. The structure obtained is expected to foster nanobody engineering in order to rescue neutralization activity and will facilitate epitope mapping for other neutralizing nanobodies by competition assays. [ABSTRACT FROM AUTHOR]

Little is known about the frequency of Zika virus (ZIKV) infections in Sudan. The aim of this study was to obtain data on the prevalence of ZIKV infections and the immunity of the population in the country. To this end, 198 sera obtained between December 2012 and January 2013 in different regions in Sudan were examined for neutralizing antibodies against ZIKV, dengue virus (DENV), and yellow fever virus (YFV). The sera were non-randomly selected. The neutralization titers were compared with each other and with the WHO 1st International Standard for anti-Asian lineage Zika virus antibody. Twenty-six sera neutralized ZIKV. One-third of these sera had higher neutralization titers against ZIKV than against DENV-2 and -3. Two sera showed higher neutralization titers than the WHO standard for ZIKV antibodies. These data suggest occasional ZIKV infections in Sudan. The low percentage of sera in this cohort that neutralized ZIKV indicates that, in the study period, the population was susceptible to ZIKV infection. [ABSTRACT FROM AUTHOR]

Background: After the global COVID-19 crisis, understanding post-infectious immunity and vaccine efficacy remains crucial. This study aims to assess anti-SARS-CoV-2 immunity through a quantitative analysis of anti-receptor-binding domain (RBD) antibodies and rapid functional testing of the neutralizing humoral response. Methods: A retrospective analysis was conducted on samples from various cohorts, including partially vaccinated, fully vaccinated, post-COVID/no-vaccination, and post-COVID/vaccination individuals with various immune-competency statuses. The anti-RBD antibodies were measured using an automated chemiluminescence assay, while the neutralizing antibodies' (NAbs') activity was assessed through the lateral flow ichroma COVID-19 nAb test (LFT), a surrogate neutralization assay. Results: The analysis revealed various levels of anti-RBD antibodies and seroneutralization responses across cohorts, with the post-COVID/vaccination group demonstrating the most robust protection. A correlation between anti-RBD antibodies and seroneutralization was observed, albeit with varying strength depending on the subgroup analyzed. Longitudinal assessment following natural infection showed an initial surge followed by a decline in both measures. A cutoff of 3.0 log10 BAU/mL was established to predict significant seroneutralization. Conclusions: The ichroma™ COVID-19 nAb test displayed high specificity and emerged as a valuable tool for monitoring anti-SARS-CoV-2 immunity. These findings contribute to understand the antibody response dynamics and underscore the potential of rapid tests in predicting protection against SARS-CoV-2 infection. [ABSTRACT FROM AUTHOR]

Adeno-associated virus (AAV)-mediated gene therapy has made significant progress in the last few decades. Nevertheless, challenges imposed by the immune system remain. The very high doses of AAV vectors used for some disorders have resulted in serious adverse events (SAEs) or even deaths, demonstrating that AAV vector doses that can safely be injected into patients are limited and for some indications below the therapeutic dose. Currently used immunosuppressive drugs have not prevented the SAEs, indicating that it may be prudent to treat patients with repeated transfer of moderate doses rather than a single injection of high doses of AAV vectors. The former approach has been avoided as AAV vectors elicit neutralizing antibodies that prevent successful reapplication of serologically crossreactive vectors. Immunosuppressive regimens that block B cell responses to AAV vectors or treatments that remove AAV neutralizing antibodies thus need to be developed to allow for a shift from toxic single-dose injections of AAV vectors to repeated treatments with more moderate and safe doses. Preventing or blocking antibody responses would also allow for redosing of patients with declining transgene product expression, or for effective AAV-mediated gene transfer into patients with the pre-existing neutralizing antibodies. [ABSTRACT FROM AUTHOR]

Serum-neutralizing antibody titers are a critical measure of vaccine immunogenicity and are used to determine flavivirus seroprevalence in study populations. An effective dengue virus (DENV) vaccine must confer simultaneous protection against viruses grouped within four antigenic serotypes. Existing flavivirus neutralization assays, including the commonly used plaque/focus reduction neutralization titer (PRNT/ FRNT) assay, require an individual assay for each virus, serotype, and strain and easily become a labor-intensive and time-consuming effort for large epidemiological studies or vaccine trials. Here, we describe a multiplex reporter virus particle neutralization titer (TetraPlex RVPNT) assay for DENV that allows simultaneous quantitative measures of antibody-mediated neutralization of infection against all four DENV serotypes in a single low-volume clinical sample and analyzed by flow cytometry. Comparative studies confirm that the neutralization titers of antibodies measured by the TetraPlex RVPNT assay are similar to FRNT/PRNT assay approaches performed separately for each viral strain. The use of this high-throughput approach enables the careful serological study in DENV endemic populations and vaccine recipients required to support the development of a safe and effective tetravalent DENV vaccine. IMPORTANCE As a mediator of protection against dengue disease and a serological indicator of prior infection, the detection and quantification of neutralizing antibodies against DENV is an important “gold standard” tool. However, execution of traditional neutralizing antibody assays is often cumbersome and requires repeated application for each virus or serotype. The optimized RVPNT assay described here is high-throughput, easily multiplexed across multiple serotypes, and targets reporter viral particles that can be robustly produced for all four DENV serotypes. The use of this transformative RVPNT assay will support the expansion of neutralizing antibody datasets to answer research and public health questions often limited by the more cumbersome neutralizing antibody assays and the need for greater quantities of test serum. [ABSTRACT FROM AUTHOR]

Marburg virus infection in humans is associated with case fatality rates that can reach up to 90%, but to date, there are no approved vaccines or monoclonal antibody (mAb) countermeasures. Here, we immunized Rhesus macaques with multivalent combinations of filovirus glycoprotein (GP) antigens belonging to Marburg, Sudan, and Ebola viruses to generate monospecific and cross-reactive antibody responses against them. From the animal that developed the highest titers of Marburg virus GP-specific neutralizing antibodies, we sorted single memory B cells using a heterologous Ravn virus GP probe and cloned and characterized a panel of 34 mAbs belonging to 28 unique lineages. Antibody specificities were assessed by overlapping pepscan and binding competition analyses, revealing that roughly a third of the lineages mapped to the conserved receptor binding region, including potent neutralizing lineages that were confirmed by negative stain electron microscopy to target this region. Additional lineages targeted a protective region on GP2, while others were found to possess cross-filovirus reactivity. Our study advances the understanding of orthomar-burgvirus glycoprotein antigenicity and furthers efforts to develop candidate antibody countermeasures against these lethal viruses. IMPORTANCE Marburg viruses were the first filoviruses characterized to emerge in humans in 1967 and cause severe hemorrhagic fever with average case fatality rates of ~50%. Although mAb countermeasures have been approved for clinical use against the related Ebola viruses, there are currently no approved countermeasures against Marburg viruses. We successfully isolated a panel of orthomarburgvirus GP-specific mAbs from a macaque immunized with a multivalent combination of filovirus antigens. Our analyses revealed that roughly half of the antibodies in the panel mapped to regions on the glycoprotein shown to protect from infection, including the host cell receptor binding domain and a protective region on the membrane-anchoring subunit. Other antibodies in the panel exhibited broad filovirus GP recognition. Our study describes the discovery of a diverse panel of cross-reactive macaque antibodies targeting orthomarburgvirus and other filovirus GPs and provides candidate immunotherapeutics for further study and development. [ABSTRACT FROM AUTHOR]

The Pfizer-BioNTech vaccine was one of the essential tools in curtailing the COVID-19 pandemic. Unlike conventional vaccines, this newly approved mRNA vaccine is taken up by cells, which leads to the synthesis of the specific viral Spike antigen. The vaccine was initially introduced for adults, and the immunological profile of adult recipients is well-characterized. The vaccine was approved for paediatric use much later after its efficacy and safety had been confirmed in children. However, the complete picture of how the paediatric immune system in children reacts to the vaccine is not well documented. Therefore, in order to better understand the immune response in children, we analysed the humoral response, immune cell count, and interferon signalling in paediatric vaccine recipients ranging between 5 and 17 years of age. Our findings suggest that the paediatric recipients elicit a robust humoral response that is sustained for at least three months. We also found that the vaccine triggered a transient lymphocytopenia similar to that observed during viral infection. Interestingly, we also found that the vaccine may sensitise the interferon signalling pathway, priming the cells to mount a potent response when exposed to interferons during a subsequent infection. The study offers new insights into the workings of the paediatric immune system and innate immunity, thereby opening the doors for further research in this field. [ABSTRACT FROM AUTHOR]

SARS‐CoV‐2 Omicron lineages continue to emerge and evolve into new sublineages, causing infection waves throughout 2022 and 2023, which has been attributed to immune escape. We examined neutralizing antibody responses to the recently emerged SARS‐CoV‐2 JN.1 variant in comparison to ancestral D614G and Omicron BA.1, BA.2, BA.5, and XBB.1.5 variants. We tested 79 human sera from cohorts with different combinations of vaccinations and infections, including 23 individuals who had been repeatedly exposed to Omicron. Individuals with a monovalent XBB.1.5 vaccine booster or XBB.1.5 breakthrough infection had robust antibody levels against all variants tested; however, JN.1 evaded antibodies in individuals after single Omicron BA.1, BA.2 or BA.5 breakthrough infections. Moreover, in the non‐vaccinated cohort, serum antibodies demonstrated almost no cross‐neutralization activities against D614G, XBB.1.5 and JN.1. after infections with earlier Omicron variants. These findings show that SARS‐CoV‐2‐immunity is heterogeneous, depending on different combinations of vaccinations and infections, and emphasize the importance of considering different immune‐backgrounds when evaluating novel variants. [ABSTRACT FROM AUTHOR]