Data on MPXV-specific T-cell responses at the single-peptide level remain limited in patients with mpox and in MVA-BN vaccinees. Here, we characterized the breadth and specificity of MPXV-specific T-cell responses at the single-peptide level after in vitro expansion with overlapping 20-mer peptides spanning the MPXV proteins H3L, A35R, and B6R. The study included 28 adult males: 15 with a history of mpox (including 6 with additional MVA-BN vaccination), 7 MVA-BN-only vaccinees, and 6 unexposed participants. All mpox and MVA-BN participants responded to at least one H3L peptide, indicating broad immunogenicity, while responses to A35R and B6R were more common in the mpox group. Notably, the breadth of B6R-specific CD4+ T-cell responses correlated with hybrid immunity (r = 0.6; p = 0.02). Interestingly, MVA-BN and mpox individuals demonstrated distinct immunodominant patterns: H3L_251-270 and H3L_211-230 were mainly recognized among mpox individuals, whereas MVA-BN recognized H3L_221-240 more frequently. High-affinity HLA binding to multiple H3L peptides suggests broad population coverage. Additional immunogenetic analysis revealed a shared TRBV15 clonotype in about 50% of mpox cases. In summary, these findings highlight H3L as a potential vaccine target, guiding the development of next-generation multi-antigen MPXV vaccines to elicit comprehensive T-cell immunity.

BACKGROUND:Invasive mould infections (IMI) cause substantial morbidity and mortality in populations at risk. Novel treatment approaches are urgently needed. Targeting immune checkpoints may reverse hyporesponsiveness of the innate and adaptive immune systems. METHODS:In this prospective, observational study, we investigated immune checkpoint expression levels on immune cells in patients with invasive aspergillosis (IA; n = 25) and mucormycosis (MU; n = 7). Healthy controls (HC; n = 5) and patients with matched haematological diseases but without IMI served as control populations (CP; n = 10). Multicolour flow cytometry analysis was used to compare immune cell subsets and the expression of immune-regulatory molecules in peripheral blood mononuclear cells (PBMCs). RESULTS:Lymphocyte subsets and immune phenotypes in PBMCs were similar between patients with IMI and haematological CP, except for regulatory T cells, which were increased in PBMCs of patients with IA and MU compared to HCs. In IA and MU, PBMCs showed increased expression of immune checkpoint molecules compared to healthy controls and matched haematological CP, with this effect being more pronounced in IA than in MU. We found heterogeneous, disease-, molecule-, and patient-specific expression patterns of immune checkpoint molecules. For example, PD-1 expression was highest in MU PBMCs, followed by IA PBMCs, while HC PBMCs showed lower expression levels. Overall mortality in our patient population was 44.0% (IPA) and 80.0% (MU). CONCLUSIONS:We report an immune phenotype consistent with T-cell exhaustion in IMI, indicating potential contributions from haematological treatment, underlying disease, and infection. However, the primary underlying cause remains unclear and requires further investigation. A marker that was notably higher in IMI patients was PD-1, and treatment approaches specifically targeting this molecule may be promising.

BACKGROUND:Rabies pre-exposure prophylaxis (PrEP) is recommended to individuals at risk for exposure to rabies. Three intramuscular doses of the purified chick embryo cell (PCEC) rabies vaccine can be administered according to a conventional (four-week) or an accelerated (one-week) regimen. METHODOLOGY/PRINCIPAL FINDINGS:This phase III, open-label study (NCT02545517) was an extension of the NCT01662440 study where immune responses of different primary PrEP regimens with PCEC rabies vaccine and Japanese encephalitis (JE) vaccine were assessed. Adults who had completed the parent study and received three doses of rabies PrEP regimens, concomitantly with a JE vaccine or alone (i.e., Rabies+JE-Accelerated, Rabies+JE-Conventional, and Rabies-Conventional groups) were enrolled in this extension study. Here we evaluated the long-term (up to 10 years after completing the primary vaccination) immunogenicity and boostability of PCEC rabies vaccine, and the safety of booster dose(s). Immunogenicity was assessed in terms of rabies virus neutralizing antibody (RVNA) concentrations, and titers ≥0.5 international units (IU)/mL were considered adequate for protection. Participants with RVNA concentrations <0.5 IU/mL were eligible for receiving PCEC rabies vaccine booster(s). Of the 459 participants enrolled in this study, 77.6% completed the trial. At the study end, the probability of detecting adequate RVNA concentrations in unboosted participants was 57.8%, 60.2%, and 62.0% for the Rabies+JE-Accelerated, Rabies+JE-Conventional, and Rabies-Conventional groups, respectively. Overall, 68.6% of all participants had RVNA concentrations ≥0.5 IU/mL at any timepoint and did not require a booster dose during the study follow-up period. Of the 144 participants with RVNA concentrations <0.5 IU/mL at any timepoint, 132 needed one booster dose throughout the follow-up period (Years 3-10) and 12 needed multiple booster administrations. No safety concerns were identified. CONCLUSION/SIGNIFICANCE:The PCEC rabies vaccine administered alone/concomitantly with the JE vaccine provides adequate immunity for up to 62% of unboosted participants at study end.

Background MERS-CoV is a respiratory pathogen with a case-fatality rate of 36%, and for which no vaccines currently licensed. MVA-MERS-S is a candidate vaccine based on recombinant modified vaccinia virus Ankara (MVA). In this study, the safety, immunogenicity, and optimal dose schedule of MVA-MERS-S was assessed in individuals with previous exposure to SARS-CoV-2 infections and vaccines. Methods We conducted a multicentre, double-blind, randomised controlled phase 1b clinical trial at two university medical centres in Germany and the Netherlands. Healthy volunteers aged 18-55 years were assigned by computer randomisation to receive three intramuscular injections of 107 or 10$ plaque-forming units (PFU) of MVA-MERS-S, with two treatment groups each of either 28-day or 56-day intervals between the initial two doses, and one control arm that received only placebo, at a ratio of 2:2:2:2:1. The third dose was given after 224 days. The sponsor, clinical laboratory staff, and participants were masked to both vaccine dose and dosing interval. The primary outcome safety, assessed in the all participants who had received at least one injection; daily solicited vaccine reactions were recorded after each dose for 7 days, unsolicited adverse events for 28 days, and serious adverse events throughout study. The secondary outcome was humoral immunogenicity, measured with vaccine-induced geometric mean antibody concentrations and seroconversion rates, analysed in all participants who received at least three allocated treatments. This study is registered at ClinicalTrials.gov (NCT04119440) and is completed. Findings Between 26 July, 2021, and 3 March, 2022, 244 volunteers were screened, 177 of whom were eligible 140 were randomly assigned either to the 28-day 107 PFU group (n=32), 56-day 107 PFU group (n=31), 28-day 10$ PFU group (n=31), 56-day 10$ PFU group (n=30), or placebo group (n=16). In total, 178 doses were administered of 107 PFU of MVA-MERS-S, 174 of 10$ PFU, and 164 doses of placebo, and 139 participants received least one injection. 73 (53%) were female and 66 (48%) were male. No serious vaccine-related adverse events occurred. Solicited local reactions were mild in 288 (93%, 95% CI 90-96) of 309 reports and consisted primarily of pain tenderness. Pain or tenderness (of any severity) occurred after 69 (39%, 32-46) of 178 107 PFU injections, 138 (79%; 73-85) of 174 10$ PFU injections, and 18 (11%; 7-11) of 164 placebo injections. Of 595 reported solicited systemic reactions, 479 (81%, 77-83) were graded as mild. Systemic reactions of any grade occurred after 77 (43%; 36-51) 107 PFU injections, 102 (59%; 51-66) 10$ PFU injections, and 67 (41%; 34-49) of 164 placebo injections. At 28 days after the second dose, MERS-CoV neutralising antibodies were highest for participants assigned to 56-day 10$ PFU, with geometric mean ratios of 7.2 (95% CI 3.9-13.3) for the 56-day 10$ PFU group versus the 28-day 10$ PFU group (p<00001), 3.9 (2.1-7.2) for the 56-day 10$ PFU group versus the 56-day 107 PFU group (p=0.0031), and 5.4 (2.9-10.0) for the 56-day 10$ PFU group versus the 28-day 107 PFU group (p=0.0003). Interpretation MVA-MERS-S was safe and immunogenic in individuals with previous and concurrent SARS-CoV-2 exposure. The second vaccination with the 10$ PFU dose of MVA-MERS-S elicited a stronger humoral immune response when administered 56 days after the first dose than a 28-day interval. Further studies are needed to verify these findings in groups at risk for MERS-CoV exposure, and at risk of severe disease, including older individuals and those with relevant comorbidities. Funding Coalition for Epidemic Preparedness Innovations, the German Centre for Infection Research, and the German Research Foundation.Copyright (c) 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.

KIR3DS1 is an activating natural killer (NK) cell receptor gene– present in 10-40% of humans– and is associated with extended AIDS-free survival. Although its ligand HLA-F has been identified, the underlying protective mechanism in HIV-1 is not yet understood. We sought to uncover the role of the KIR3DS1/HLA-F axis through investigating HLA-F surface and transcriptional changes during acute and chronic HIV-1 infection. HLA-F+ CD4 T cells were detected in people living with HIV (PLHIV) without antiretroviral treatment (N=102) and frequencies correlated with viremia but not with CD4 T cell count. Single-cell transcriptome analyses of PLHIV following acute HIV-1 acquisition revealed increased HLA-F mRNA levels in CD4 T cells associated with innate signaling signatures. In vitro, HLA-F mRNA was upregulated in both HIV-1–infected and bystander CD4 T cells. Functional studies demonstrated that bystander-activated CD4 T cells were reduced in the presence of NK cells during HIV-1 infection, and depleting NK cells increased the frequency of HLA-F+ CD4 T cells. Genotyping of our cohort revealed that KIR3DS1+ PLHIV exhibited significantly lower frequencies of HLA-F+ CD4 T cells. Taken together, these results establish HLA-F as a novel marker of innate T cell activation that is linked to HIV-1 viremia and suggest an immunoregulatory role of NK cells in controlling HIV-1-mediated inflammation by killing activated bystander CD4 T cells.

Infectious diseases have threatened individuals and societies since the dawn of humanity. Certain population groups, including pregnant women, young children and the elderly, are particularly vulnerable to severe infections. Over the past few centuries, advances in medical standards and the availability of vaccines have reduced infection-related mortality and morbidity rates in industrialized countries. However, the global rise in temperatures and increased precipitation present a new challenge, facilitating the broader distribution of disease vectors, such as mosquitoes, bugs and ticks, to higher altitudes and latitudes. Consequently, epidemic and pandemic outbreaks associated with these vectors, such as Zika, West Nile, dengue, yellow fever, chikungunya and malaria, are increasingly impacting diverse populations. This review comprehensively examines how infections associated with climate change disproportionately affect the health and well-being of pregnant women and their unborn children. There has been a noticeable emergence of vector-borne diseases in Europe. Consequently, we stress the importance of implementing measures that effectively protect pregnant women from these increasing infections globally and regionally. We advocate for initiatives to safeguard pregnant women from these emerging threats, beginning with enhanced education to raise awareness about the evolving risks this particularly vulnerable population faces.

BACKGROUND:Neonatal mortality remains high in many low- and middle-income countries (LMICs), with neonatal sepsis and antimicrobial resistance (AMR) posing significant threats to newborns, particularly in sub-Saharan Africa (SSA). Tanzania is among the countries with the highest neonatal mortality rates, with sepsis being a major contributor. Gut dysbiosis has been identified as a risk factor for neonatal sepsis in high-income countries, due to factors like abundance of pathogenic bacteria, decrease in microbiome diversity, intestinal barrier defects and bacterial translocation. Understanding gut dysbiosis in the local setting and its role in sepsis development may offer new prevention strategies, such as probiotics for high-risk preterm infants. OBJECTIVES:This prospective neonatal cohort, established at Muhimbili National Hospital (MNH) in Dar es Salaam, Tanzania, aims to analyze the gut microbiome of preterm infants and explore associations with neonatal late-onset sepsis (LOS). Additionally, data on bacterial pathogens of bloodstream infections and AMR prevalence will be identified. Secondary endpoints include clinical LOS, sepsis-related death, death from any cause, and hospital discharge outcomes. METHODS:Eligible preterm neonates (28 + 0 to <34 weeks of gestational age, birth weight ≥ 1000g) will be recruited with maternal consent. Socio-demographic and clinical data, microbiological details of blood pathogens, and a set of fresh frozen fecal samples during the 28 days observation period will be collected. The study targets a sample size of 1350 participants and we expect 72-135 culture-proven LOS during a study period of 18 months. Fecal samples will undergo next-generation sequencing (NGS) to analyze microbial community functions in comparison to matched controls. DISCUSSION:This collaborative study between universities in Tanzania and Germany, aims to analyze the neonatal microbiome in relation to sepsis development and AMR of blood culture isolates to enhance neonatal sepsis care, improve diagnostics and treatment. The project will offer insights into potential therapeutic strategies for the future, promote academic exchange, capacity building and research on African microbiomes.

Infants depend on passive immunity to safeguard them against infections during the first months of life. Maternal immunoglobulin G (IgG) antibodies are actively transported across the placenta and confer this protection. In this study, we discovered common, but previously unrecognized, naturally occurring gene fusions between loci encoding IgG1 and IgG4 subclasses that impair the transplacental IgG transport. These gene fusions result from gene duplications combining regulatory elements of the Immunoglobulin Heavy Constant Gamma (IGHG1) gene with IGHG4-like constant regions. Mothers with these duplications generate antibodies that are less efficiently transferred to the fetus, resulting in lower antibody levels in newborns and a higher risk of respiratory infections during infancy. Our insights warrant consideration in the development of personalized vaccination strategies during pregnancy to better protect infants against infectious diseases. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement German Center for Child and Adolescent Health, Hamburg site (PCA, AD) Federal Ministry of Research and Education, Junior Research Center on Reproduction (PCA, AD) German Research Foundation (KFO296: DI2103/2-2 (AD), AR232/24-2 (PCA), RU5068: AR232/29-2 (PCA), CRC 1713: 91232/1-1713 (PCA, AD), SCHL2276/2-1 (CS), TRR333/1, 450149205 (CS) Next Generation Partnership, Excellence Initiative University Hamburg (PCA, AD) State Ministry of Research and Education and Equality (LFF-FV73) (PCA, AD) Werner Otto Foundation (DEZ) Leibniz Science Campus InterACt (supported by the BWFGB Hamburg and the Leibniz Association) (KMC, MT) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All study participants provided signed informed consent forms. The study protocol was approved by the ethics committee of the Hamburg Chamber of Physicians (license number PV 3694). It was conducted in compliance with the Declaration of Helsinki for Medical Research involving Human Subjects. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors

Mycophenolic acid (MPA) is commonly used in immunosuppressive regimens following solid organ transplantation. We demonstrate that MPA treatment reproducibly inhibits the replication of a range of viruses, including severe respiratory syndrome coronavirus 2 (SARS-CoV-2). Mechanistically, we identified cellular guanosine triphosphate pool depletion as a key mediator of this antiviral effect. Strikingly, this inhibition can be overcome which was correlated with the emergence of three breakthrough mutations in the SARS-CoV-2 genome (S P812R, ORF3 Q185H, and E S6L). Subsequent analyses confirmed that the combination of these mutations conferred accelerated replication kinetics, higher viral titers, and more rapid onset of cytopathic effects, but not MPA resistance. Comparison of global transcriptional responses to infection highlighted dysregulation of specific cellular gene programs under MPA treatment prior to breakthrough mutation emergence. Together, these findings identify viral and host drivers of variant emergence under immunosuppression. They also advocate for close monitoring of immunosuppressed patients, where emergence of novel viral variants with a fitness advantage may arise.

Acute febrile diseases transmitted by mosquitos are a diagnostic challenge for pediatricians working in sub-Saharan Africa. Misclassification due to the lack of rapid, reliable diagnostic tests leads to the overuse of antibiotics and antimalarials. Children presenting with acute fever and suspected of having malaria were examined at health care facilities in the Mwanza Region of Tanzania. The sensitivity and specificity of blood smear microscopy and malaria rapid diagnostic tests that targeted histidine-rich protein 2 and Plasmodium lactate dehydrogenase were compared with a multiplex reverse transcriptase-polymerase chain reaction (PCR)-ELISA. Six hundred ninety-eight children presented with acute fever and met the criteria for inclusion; 23% received antibiotics and 23% received antimalarials prior to admission. Subsequently, 20% were confirmed by PCR to have Plasmodium falciparum infection. Blood smear microscopy exhibited 33% sensitivity and 93% specificity. The malaria rapid test provided 87% sensitivity and 98% specificity in detecting acute malaria infections. Only 7% of malaria-negative children received antimalarials at Sengerema Designated District Hospital when treatment was guided by the results of rapid testing. In contrast, 75% of malaria-negative patients were treated with antimalarial drugs at health facilities that used blood smears as the standard diagnostic test. Misclassification and premedication of nonmalarial, febrile illnesses contribute to the emergence of antimalarial and antimicrobial resistance. The incorporation of malaria rapid diagnostic tests into the clinical routine translated into improved treatment and a significant reduction in antimalarial drug prescriptions.

The rapid development of safe and effective vaccines helped to prevent severe disease courses after SARS-CoV-2 infection and to mitigate the progression of the COVID-19 pandemic. While there is evidence that vaccination may reduce the risk of developing post-COVID-19 conditions (PCC), this effect may depend on the viral variant. Therapeutic effects of post-infection vaccination have been discussed but the data for individuals with PCC remains inconclusive. In addition, extremely rare side effects after SARS-CoV-2 vaccination may resemble the heterogeneous PCC phenotype. Here, we analyze the plasma levels of 25 cytokines and SARS-CoV-2 directed antibodies in 540 individuals with or without PCC relative to one or two mRNA-based COVID-19 vaccinations as well as in 20 uninfected individuals one month after their initial mRNA-based COVID-19 vaccination. While none of the SARS-CoV-2 naïve individuals reported any persisting sequelae or exhibited PCC-like dysregulation of plasma cytokines, we detected lower levels of IL-1β and IL-18 in patients with ongoing PCC who received one or two vaccinations at a median of six months after infection as compared to unvaccinated PCC patients. This reduction correlated with less frequent reporting of persisting gastrointestinal symptoms. These data suggest that post-infection vaccination in patients with PCC might be beneficial in a subgroup of individuals displaying gastrointestinal symptoms.

In response to the COVID-19 pandemic, multiple vaccines were developed using platforms such as viral vectors and mRNA technology. Here, we report humoral and cellular immunogenicity data from human phase 1 clinical trials investigating two recombinant Modified Vaccinia virus Ankara vaccine candidates, MVA-SARS-2-S and MVA-SARS-2-ST, encoding the native and the prefusion-stabilized SARS-CoV-2 spike protein, respectively. MVA-SARS-2-ST was more immunogenic than MVA-SARS-2-S, but both were less immunogenic compared to licensed mRNA- and ChAd-based vaccines in SARS-CoV-2 naïve individuals. In heterologous vaccination, previous MVA-SARS-2-S vaccination enhanced T cell functionality and MVA-SARS-2-ST boosted the frequency of T cells and S1-specific IgG levels when used as a third vaccination. While the vaccine candidate containing the prefusion-stabilized spike elicited predominantly S1-specific responses, immunity to the candidate with the native spike was skewed towards S2-specific responses. These data demonstrate how the spike antigen conformation, using the same viral vector, directly affects vaccine immunogenicity in humans.