Search

BackgroundBaricitinib and dexamethasone have randomised trials supporting their use for the treatment of patients with COVID-19. We assessed the combination of baricitinib plus remdesivir versus dexamethasone plus remdesivir in preventing progression to mechanical ventilation or death in hospitalised patients with COVID-19.MethodsIn this randomised, double-blind, double placebo-controlled trial, patients were enrolled at 67 trial sites in the USA (60 sites), South Korea (two sites), Mexico (two sites), Singapore (two sites), and Japan (one site). Hospitalised adults (≥18 years) with COVID-19 who required supplemental oxygen administered by low-flow (≤15 L/min), high-flow (>15 L/min), or non-invasive mechanical ventilation modalities who met the study eligibility criteria (male or non-pregnant female adults ≥18 years old with laboratory-confirmed SARS-CoV-2 infection) were enrolled in the study. Patients were randomly assigned (1:1) to receive either baricitinib, remdesivir, and placebo, or dexamethasone, remdesivir, and placebo using a permuted block design. Randomisation was stratified by study site and baseline ordinal score at enrolment. All patients received remdesivir (≤10 days) and either baricitinib (or matching oral placebo) for a maximum of 14 days or dexamethasone (or matching intravenous placebo) for a maximum of 10 days. The primary outcome was the difference in mechanical ventilation-free survival by day 29 between the two treatment groups in the modified intention-to-treat population. Safety analyses were done in the as-treated population, comprising all participants who received one dose of the study drug. The trial is registered with ClinicalTrials.gov, NCT04640168.FindingsBetween Dec 1, 2020, and April 13, 2021, 1047 patients were assessed for eligibility. 1010 patients were enrolled and randomly assigned, 516 (51%) to baricitinib plus remdesivir plus placebo and 494 (49%) to dexamethasone plus remdesivir plus placebo. The mean age of the patients was 58·3 years (SD 14·0) and 590 (58%) of 1010 patients were male. 588 (58%) of 1010 patients were White, 188 (19%) were Black, 70 (7%) were Asian, and 18 (2%) were American Indian or Alaska Native. 347 (34%) of 1010 patients were Hispanic or Latino. Mechanical ventilation-free survival by day 29 was similar between the study groups (Kaplan-Meier estimates of 87·0% [95% CI 83·7 to 89·6] in the baricitinib plus remdesivir plus placebo group and 87·6% [84·2 to 90·3] in the dexamethasone plus remdesivir plus placebo group; risk difference 0·6 [95% CI -3·6 to 4·8]; p=0·91). The odds ratio for improved status in the dexamethasone plus remdesivir plus placebo group compared with the baricitinib plus remdesivir plus placebo group was 1·01 (95% CI 0·80 to 1·27). At least one adverse event occurred in 149 (30%) of 503 patients in the baricitinib plus remdesivir plus placebo group and 179 (37%) of 482 patients in the dexamethasone plus remdesivir plus placebo group (risk difference 7·5% [1·6 to 13·3]; p=0·014). 21 (4%) of 503 patients in the baricitinib plus remdesivir plus placebo group had at least one treatment-related adverse event versus 49 (10%) of 482 patients in the dexamethasone plus remdesivir plus placebo group (risk difference 6·0% [2·8 to 9·3]; p=0·00041). Severe or life-threatening grade 3 or 4 adverse events occurred in 143 (28%) of 503 patients in the baricitinib plus remdesivir plus placebo group and 174 (36%) of 482 patients in the dexamethasone plus remdesivir plus placebo group (risk difference 7·7% [1·8 to 13·4]; p=0·012).InterpretationIn hospitalised patients with COVID-19 requiring supplemental oxygen by low-flow, high-flow, or non-invasive ventilation, baricitinib plus remdesivir and dexamethasone plus remdesivir resulted in similar mechanical ventilation-free survival by day 29, but dexamethasone was associated with significantly more adverse events, treatment-related adverse events, and severe or life-threatening adverse events. A more individually tailored choice of immunomodulation now appears possible, where side-effect profile, ease of administration, cost, and patient comorbidities can all be considered.FundingNational Institute of Allergy and Infectious Diseases.

Mycobacterium tuberculosis (Mtb) is a leading cause of global infectious disease mortality. The vaccine for Mtb, Bacillus Calmette-Guérin (BCG), was originally developed as an oral vaccine, but is now given intradermally.

PDF file, 944K, IP-10 is the only functional chemokine inducing the migration of �� Treg cells.

Supplementary Data from MCPIP1 Selectively Destabilizes Transcripts Associated with an Antiapoptotic Gene Expression Program in Breast Cancer Cells That Can Elicit Complete Tumor Regression

PDF file, 2822K, Correlation analyses of tumor-infiltrating �� T cells and tumor IP-10 expression levels in human breast cancer tissues.

The ability of cancer cells to evade apoptosis is dictated by a shift in the balance between proapoptotic and antiapoptotic gene expression programs. Monocyte chemotactic protein-induced protein 1 (MCPIP1) is a zinc-finger RNA binding protein with important roles in mediating inflammatory responses. Overexpression of MCPIP1 in different cancer cell types has been implicated in eliciting an antitumor response, but a direct role of MCPIP1 in apoptosis has not been established. In this study, we demonstrate that MCPIP1 functions as a potent tumor suppressor that induces apoptosis of breast tumor cells by selectively enhancing mRNA decay of antiapoptotic gene transcripts, including Bcl2L1, Bcl2A1, RelB, Birc3, and Bcl3. Mechanistically, MCPIP1 physically interacted with a stem–loop structure in the 3′ untranslated region of these transcripts through its PIN domain, causing mRNA destabilization. Furthermore, we found that MCPIP1 expression was repressed in breast tumor cells, and overexpression of MCPIP1 induced apoptosis, whereas its depletion enhanced cancer cell proliferation. Moreover, MCPIP1 induction in vivo resulted in complete regression of established tumors and a significant reduction in metastatic disease. Notably, low MCPIP1 expression in tumor samples from breast cancer patients was strongly associated with poor survival over 13 years of follow-up. Collectively, our results highlight that MCPIP1 is a new tumor suppressor in breast cancer that induces cell death by tipping the balance in favor of proapoptotic gene expression. Cancer Res; 76(6); 1429–40. ©2016 AACR.

PDF file, 4006K, Neutralization of IP-10 does not affect the trafficking and distribution of tumor-specific effector CD8+ TIL586 cells into tumor sites in tumor-bearing mice.

PDF file, 119K.

Adjuvant-containing subunit vaccines represent a promising approach for protection against tuberculosis (TB), but current candidates require refrigerated storage. Here we present results from a randomized, double-blinded Phase 1 clinical trial (NCT03722472) evaluating the safety, tolerability, and immunogenicity of a thermostable lyophilized single-vial presentation of the ID93 + GLA-SE vaccine candidate compared to the non-thermostable two-vial vaccine presentation in healthy adults. Participants were monitored for primary, secondary, and exploratory endpoints following intramuscular administration of two vaccine doses 56 days apart. Primary endpoints included local and systemic reactogenicity and adverse events. Secondary endpoints included antigen-specific antibody (IgG) and cellular immune responses (cytokine-producing peripheral blood mononuclear cells and T cells). Both vaccine presentations are safe and well tolerated and elicit robust antigen-specific serum antibody and Th1-type cellular immune responses. Compared to the non-thermostable presentation, the thermostable vaccine formulation generates greater serum antibody responses (p p

Metabolic reprogramming of cancer cells creates a unique tumor microenvironment (TME) characterized by the limited availability of nutrients, which subsequently affects the metabolism, differentiation, and function of tumor-infiltrating T lymphocytes (TILs). TILs can also be inhibited by tumor-derived metabolic waste products and low oxygen. Therefore, a thorough understanding of how such unique metabolites influence mammalian T cell differentiation and function can inform novel anti-cancer therapeutic approaches. Here, we highlight the importance of these metabolites in modulating various T cell subsets within the TME, dissecting how these changes might alter clinical outcomes. We explore potential TME metabolic determinants that might constitute candidate targets for cancer immunotherapies, ideally leading to future strategies for reprogramming tumor metabolism to potentiate anti-cancer T cell functions.

Background We evaluated the associations between baseline influenza virus–specific hemagglutination inhibition (HAI) and microneutralization (MN) titers and subsequent symptomatic influenza virus infection in a controlled human infection study. Methods We inoculated unvaccinated healthy adults aged 18–49 years with an influenza A/California/04/2009/H1N1pdm-like virus (NCT04044352). We collected serial safety labs, serum for HAI and MN, and nasopharyngeal swabs for reverse-transcription polymerase chain reaction (RT-PCR) testing. Analyses used the putative seroprotective titer of ≥40 for HAI and MN. The primary clinical outcome was mild-to-moderate influenza disease (MMID), defined as ≥1 postchallenge positive qualitative RT-PCR test with a qualifying symptom/clinical finding. Results Of 76 participants given influenza virus challenge, 54 (71.1%) experienced MMID. Clinical illness was generally very mild. MMID attack rates among participants with baseline titers ≥40 by HAI and MN were 64.9% and 67.9%, respectively, while MMID attack rates among participants with baseline titers Conclusions We achieved a 71.1% attack rate of MMID. High baseline HAI and MN were associated with protection from illness. Clinical Trials Registration. NCT04044352.

Background Two Taiwan based studies indicated influenza vaccinations are associated with lower risk for dementia in patient cohorts with chronic disease. We determined if such associations exist in a large, nationally distributed sample of U.S. patients not selected for chronic disease. Methods Data was obtained from Veterans Health Administration medical records (9/1/2009 – 8/31/19). Eligible patients were ≥65 years of age and free of dementia for two years prior to enrollment through the end of the first influenza season (9/1/2009 to 3/1/2012). Competing risk models estimated the risk of dementia in those with influenza vaccination (n = 66,822) compared to those without vaccination (n = 56,925). Propensity scores and inverse probability of treatment weighting controlled for confounding. Results On average, patients were 75.5 (±7.3) years of age, 3.8% were female and 91.6% were white race. After controlling for confounding, patients with influenza vaccination were significantly less likely to develop dementia compared to patients without vaccination (HR = 0.86; 95 %CI:0.83–0.88). Patients with 1, 2 or 3–5 vaccines vs. none had similar risks for dementia and patients with ≥ 6 influenza vaccines vs. none had a significant lower risk for dementia (HR = 0.88, 95 %CI: 0.83–0.94). Conclusions Repeated receipt of influenza vaccinations, compared to remaining unvaccinated, is associated with lower risk for dementia. This is consistent with the hypotheses that vaccinations may reduce risk of dementia by training the immune system and not by preventing specific infectious disease. If vaccines are identified as causative factors in reducing incident dementia, they offer an inexpensive, low-risk intervention with effects greater than any existing preventive measure.

IntroductionTrypanosoma cruzi is the protozoan parasite causing Chagas disease, a Neglected Tropical Disease that affects 8 million people and causes 12,000 deaths per year, primarily because of cardiac pathology. Effective vaccination for T. cruzi remains an elusive goal. The use of a live vaccine vector, especially one that mimics the pathogen target, may be superior to the use of recombinant protein or DNA vaccine formulations.MethodsWe generated recombinant Leishmania major, a related trypanosomatid parasite, as a vaccine vehicle to express the immunogenic T. cruzi trans-sialidase (TS) antigen. The induction of T cell and antibody responses, as well as T. cruzi protective immunity generated by these vaccines were assessed in vivo.ResultsWe demonstrate that mice inoculated with these recombinant TS-expressing L. major parasites mount T cell and antibody responses directed against TS and are protected against future T. cruzi infection. We also show that the partially attenuated dhfr-ts- CC1 L. major strain, previously found to induce protective immunity to virulent L. major infection without causing pathology, can also be engineered to express the TS antigen. This latter recombinant may represent a safe and effective option to explore for ultimate use in humans.DiscussionAltogether, these data indicate that L. major can stably express a T. cruzi antigen and induce T. cruzi-specific protective immunity, warranting further investigation of attenuated Leishmania parasites as vaccine.

BackgroundInfluenza controlled human infection model (CHIM) studies can advance development of vaccines and therapeutics. Our objective was to evaluate the associations between baseline challenge virus-specific hemagglutination inhibition (HAI) and microneutralization (MN) titers and subsequent symptomatic influenza virus infection.MethodsWe enrolled healthy adults aged 18 through 49 years in a multisite CHIM study using influenza A/Bethesda/MM2/H1N1, an A/California/04/2009/H1N1pdm-like virus (NCT04044352). We excluded persons vaccinated against influenza within the previous six months. We collected serial safety labs, serum for HAI and MN, and nasopharyngeal swabs for RT-PCR testing. Analyses used the putative seroprotective titer of ≥40 for HAI and MN. The primary clinical outcome was mild-to-moderate influenza disease (MMID), defined as ≥1 post-challenge positive qualitative RT-PCR test with a qualifying symptom/clinical finding.FindingsOf 76 participants given influenza virus challenge, 54 (71.1%) experienced MMID. Clinical illness post-challenge was generally very mild. MMID attack rates among participants with baseline titers ≥40 by HAI and MN were 64.9% and 67.9%, respectively, while MMID attack rates among participants with baseline titers InterpretationIn a multi-site influenza CHIM study, we assured the safety of our participants and achieved a 71.1% attack rate of MMID. High baseline HAI and MN were associated with protection from illness.

We generated recombinantWe demonstrate that mice inoculated with these recombinant TS-expressingAltogether, these data indicate that

Over the last decade, the field of systems vaccinology has emerged, in which high throughput transcriptomics and other omics assays are used to probe changes of the innate and adaptive immune system in response to vaccination. RNA-Seq technology has matured in recent years and is now widely deployed for transcriptional analysis of clinical specimens. The goal of this study was to benchmark technical parameters of RNA-Seq in the context of a multi-site, double-blind randomized clinical trial using primary patient samples. We collected longitudinal peripheral blood mononuclear cell (PBMC) samples from 10 subjects after vaccination with a live attenuated Francisella tularensis vaccine and performed RNA-Seq at two different sites using aliquots from the same sample to generate two large-scale replicate datasets. We evaluated the impact of: (i) filtering lowly-expressed genes, (ii) using external RNA controls, (iii) fold change and false discovery rate (FDR) filtering, (iv) read length, and (v) sequencing depth on differential expressed genes (DEGs) concordance between replicate datasets. Using synthetic mRNA spike-ins, we developed a method for empirically establishing minimal read-count thresholds for maintaining fold change accuracy on a per-experiment basis. We defined a reference PBMC transcriptome by pooling sequence data, and established the impact of read depth and gene filtering on transcript representation. Lastly, we modeled statistical power to detect DE genes for a range of sample sizes, effect sizes, and coverage depths. The results from this study provide RNA sequencing benchmarks and guidelines for planning future similar vaccine studies.

Plasmalogens are plasma-borne antioxidant phospholipid species that provide protection as cellular lipid components during cellular oxidative stress. In this study we investigated plasma plasmalogen levels in human sepsis as well as in rodent models of infection. In humans, levels of multiple plasmenylethanolamine molecular species were decreased in septic patient plasma compared to control subject plasma as well as an age-aligned control subject cohort. Additionally, lysoplasmenylcholine levels were significantly decreased in septic patients compared to the control cohorts. In contrast, plasma diacyl phosphatidylethanolamine and phosphatidylcholine levels were elevated in septic patients. Lipid changes were also determined in rats subjected to cecal slurry sepsis. Plasma plasmenylcholine, plasmenylethanolamine, and lysoplasmenylcholine levels were decreased while diacyl phosphatidylethanolamine levels were increased in septic rats compared to control treated rats. Kidney levels of lysoplasmenylcholine as well as plasmenylethanolamine molecular species were decreased in septic rats. Interestingly, liver plasmenylcholine and plasmenylethanolamine levels were increased in septic rats. Since COVID-19 is associated with sepsis-like acute respiratory distress syndrome and oxidative stress, plasmalogen levels were also determined in a mouse model of COVID-19 (intranasal inoculation of K18 mice with SARS-CoV-2). 3 days following infection, lung infection was confirmed as well as cytokine expression in the lung. Multiple molecular species of lung plasmenylcholine and plasmenylethanolamine were decreased in infected mice. In contrast, the predominant lung phospholipid, dipalmitoyl phosphatidylcholine, was not decreased following SARS-CoV-2 infection. Additionally total plasmenylcholine levels were decreased in the plasma of SARS-CoV-2 infected mice. Collectively, these data demonstrate the loss of plasmalogens during both sepsis and SARS-CoV-2 infection. This study also indicates plasma plasmalogens should be considered in future studies as biomarkers of infection and as prognostic indicators for sepsis and COVID-19 outcomes.

Background Adult vaccinations may reduce risk for dementia. However, it has not been established whether tetanus, diphtheria, pertussis (Tdap) vaccination is associated with incident dementia. Methods Hypotheses were tested in a Veterans Health Affairs (VHA) cohort and replicated in a MarketScan medical claims cohort. Patients were at least 65 years of age and free of dementia for 2 years prior to index date. Patients either had or did not have a Tdap vaccination by the start of either of the 2 index periods (2011 or 2012). Follow-up continued through 2018. Controls had no Tdap vaccination for the duration of follow-up. Confounding was controlled using entropy balancing. Competing risk (VHA) and Cox proportional hazard (MarketScan) models estimated the association between Tdap vaccination and incident dementia in all patients and age subgroups (65–69, 70–74, and ≥75 years). Results VHA patients were, on average, 75.6 (SD ± 7.5) years of age, 4% female, and 91.2% were White. MarketScan patients were 69.8 (SD ± 5.6) years of age, on average and 65.4% were female. After controlling for confounding, patients with, compared to without, Tdap vaccination had a significantly lower risk for dementia in both cohorts (VHA: hazard ratio [HR] = 0.58; 95% confidence interval [CI]:0.54–0.63 and MarketScan: HR = 0.58; 95% CI:0.48–0.70). Conclusions Tdap vaccination was associated with a 42% lower dementia risk in 2 cohorts with different clinical and sociodemographic characteristics. Several vaccine types are linked to decreased dementia risk, suggesting that these associations are due to nonspecific effects on inflammation rather than vaccine-induced pathogen-specific protective effects.

Cytotoxic lymphocytes release proteins contained within the cytoplasmic cytolytic granules after recognition of infected or tumor target cells. These cytotoxic granular proteins (namely granzymes, granulysin, and perforin) are key immunological mediators within human cellular immunity. The availability of highly purified cytotoxic proteins has been fundamental for understanding their function in immunity and mechanistic involvement in sepsis and autoimmunity. Methods for recovery of native cytotoxic proteins can be problematic leading to: 1) the co-purification of additional proteins, confounding interpretation of function, and 2) low yields of highly purified proteins. Recombinant protein expression of individual cytolytic components can overcome these challenges. The use of mammalian expression systems is preferred for optimal post-translational modifications and avoidance of endotoxin contamination. Some of these proteins have been proposed for host directed human therapies (e.g. - granzyme A), or treatment of systemic infections or tumors as in granulysin. We report here a novel expression system using HEK293T cells for cost-effective purification of high yields of human granzymes (granzyme A and granzyme B) and granulysin with enhanced biological activity than previous reports. The resulting proteins are free of native contaminants, fold correctly, and remain enzymatically active. Importantly, these improvements have also led to the first purification of biologically active recombinant human granulysin in high yields from a mammalian system. This method can be used as a template for purification of many other secreted cellular proteins and may lead to advances for human medicine.

The scientific response to the SARS-CoV-2 virus outbreak has been nothing short of breathtaking. Within 7 months of virus discovery, over 75,000 virus isolates around the world were sequenced and w...

Controlled human infection models can be helpful to study pathogenesis and immune responses as a basis for the development of vaccines. In controlled human infection models, human challenge agents are used to infect healthy volunteers, therefore, ethical considerations include that the exposure studies need to be safe and results should be meaningful, e.g. contribute to a better cure. Both in the US and in Europe, the level of Good Manufacturing Practice required is related to the phase of the study ('sliding scale Good Manufacturing Practice'), and, hence, is much more open to speedy drug development than anticipated. Recommendations included: the development of guidelines for human challenge agents; a focus on strain selection, in particular with regard to strain infectivity, stability and purity; the use of whole genome sequencing; a reference repository of challenge agents, the need for early exchange with regulators to ensure acceptability of strain selection and manufacturing for later drug development; sharing of models and challenge agents.

The functional state of the preexisting T cells in the tumor microenvironment is a key determinant for effective antitumor immunity and immunotherapy. Increasing evidence suggests that immunosenescence is an important state of T cell dysfunction that is distinct from exhaustion, a key strategy used by malignant tumors to evade immune surveillance and sustain the suppressive tumor microenvironment. Here, we discuss the phenotypic and functional characteristics of senescent T cells and their role in human cancers. We also explore the possible mechanisms and signaling pathways responsible for induction of T cell senescence by malignant tumors, and then discuss potential strategies to prevent and/or reverse senescence in tumor-specific T cells. A better understanding of these critical issues should provide novel strategies to enhance cancer immunotherapy.

Plasmalogens are a class of phospholipids containing vinyl ether linked aliphatic groups at the sn-1 position. Plasmalogens are known to contain 16- and 18-carbon aliphatic groups at the sn-1 position. Here, we reveal that the human neutrophil plasmenylethanolamine pool uniquely includes molecular species with very long carbon chain (VLC) aliphatic groups, including 20-, 22- and 24-carbon vinyl ether linked aliphatic groups at the sn-1 position. We identified these novel VLC plasmalogen species by electrospray ionization mass spectrometry methods. VLC plasmalogens were only found in the neutrophil plasmenylethanolamine pool. During neutrophil activation, VLC plasmenylethanolamines undergo myeloperoxidase-dependent oxidation to produce VLC 2-chlorofatty aldehyde and its oxidation product, 2-chlorofatty acid (2-ClFA). Furthermore, plasma concentrations of VLC 2-ClFA are elevated in human sepsis. These studies demonstrate for the first time VLC plasmenylethanolamine molecular species, their myeloperoxidase-mediated chlorolipid products and the presence of these chlorolipids in human sepsis., Graphical abstract Image 1, Highlights • Novel very long chain (VLC) plasmenylethanolamine molecular species are discovered in human neutrophils. • VLC plasmenylethanolamines undergo myeloperoxidase dependent oxidation to produce new VLC chlorinated lipids. • VLC 2-chlorofatty acids are elevated in human sepsis.

Multiple types of vaccinations are associated with lower risk for dementia, but it is not known if receiving more than one vaccination type is associated with a greater decrease in incident dementia as compared with receiving only one type. We determined if dementia risk is lowest in patients who receive both herpes zoster (HZ) and tetanus, diphtheria, pertussis (Tdap) vaccinations as compared with receipt of only one or the other type of vaccination.Primary analysis in a Veterans Health Administration (VA) cohort was replicated in private sector medical claims data. Eligible patients were ≥65 years of age and free of dementia for 2 years prior to baseline (VHA n = 80,070; MarketScan n = 129,200). At index, patients either had both HZ and Tdap, only HZ, only Tdap, or neither vaccination. Confounding was controlled with generalized boosted propensity scores and inverse probability of treatment weighting. Competing risk (VHA) and Cox proportional hazard (MarketScan) models estimated the association between vaccination status and incident dementia.VHA patients' mean age was 76.8 ± 7.6 years, 4.4% were female and 90.9% were White, and MarketScan patients' mean age was 70.5 ± 5.9 and 65.4% were female. In both cohorts, having both HZ and Tdap vaccinations compared with no vaccination was significantly associated with lower dementia risk (VHA HR = 0.50; 95% CI: 0.43-0.59; MarketScan HR = 0.58; 95% CI: 0.38-0.89). In both cohorts, compared with neither vaccination, patients with only one or the other vaccination types had a significantly lower risk for dementia. Incident dementia was lower in patients with both vaccinations versus only one vaccination type.Receiving two types of vaccinations versus one type was associated with lower dementia risk. Vaccinations may have non-specific associations with incident dementia. Low cost and accessible, common adult vaccinations may be an overlooked intervention for reducing dementia risk.

Summary Background Functional impairment of interferon, a natural antiviral component of the immune system, is associated with the pathogenesis and severity of COVID-19. We aimed to compare the efficacy of interferon beta-1a in combination with remdesivir compared with remdesivir alone in hospitalised patients with COVID-19. Methods We did a double-blind, randomised, placebo-controlled trial at 63 hospitals across five countries (Japan, Mexico, Singapore, South Korea, and the USA). Eligible patients were hospitalised adults (aged ≥18 years) with SARS-CoV-2 infection, as confirmed by a positive RT-PCR test, and who met one of the following criteria suggestive of lower respiratory tract infection: the presence of radiographic infiltrates on imaging, a peripheral oxygen saturation on room air of 94% or less, or requiring supplemental oxygen. Patients were excluded if they had either an alanine aminotransferase or an aspartate aminotransferase concentration more than five times the upper limit of normal; had impaired renal function; were allergic to the study product; were pregnant or breast feeding; were already on mechanical ventilation; or were anticipating discharge from the hospital or transfer to another hospital within 72 h of enrolment. Patients were randomly assigned (1:1) to receive intravenous remdesivir as a 200 mg loading dose on day 1 followed by a 100 mg maintenance dose administered daily for up to 9 days and up to four doses of either 44 μg interferon beta-1a (interferon beta-1a group plus remdesivir group) or placebo (placebo plus remdesivir group) administered subcutaneously every other day. Randomisation was stratified by study site and disease severity at enrolment. Patients, investigators, and site staff were masked to interferon beta-1a and placebo treatment; remdesivir treatment was given to all patients without masking. The primary outcome was time to recovery, defined as the first day that a patient attained a category 1, 2, or 3 score on the eight-category ordinal scale within 28 days, assessed in the modified intention-to-treat population, defined as all randomised patients who were classified according to actual clinical severity. Safety was assessed in the as-treated population, defined as all patients who received at least one dose of the assigned treatment. This trial is registered with ClinicalTrials.gov , NCT04492475 . Findings Between Aug 5, 2020, and Nov 11, 2020, 969 patients were enrolled and randomly assigned to the interferon beta-1a plus remdesivir group (n=487) or to the placebo plus remdesivir group (n=482). The mean duration of symptoms before enrolment was 8·7 days (SD 4·4) in the interferon beta-1a plus remdesivir group and 8·5 days (SD 4·3) days in the placebo plus remdesivir group. Patients in both groups had a time to recovery of 5 days (95% CI not estimable) (rate ratio of interferon beta-1a plus remdesivir group vs placebo plus remdesivir 0·99 [95% CI 0·87–1·13]; p=0·88). The Kaplan-Meier estimate of mortality at 28 days was 5% (95% CI 3–7%) in the interferon beta-1a plus remdesivir group and 3% (2–6%) in the placebo plus remdesivir group (hazard ratio 1·33 [95% CI 0·69–2·55]; p=0·39). Patients who did not require high-flow oxygen at baseline were more likely to have at least one related adverse event in the interferon beta-1a plus remdesivir group (33 [7%] of 442 patients) than in the placebo plus remdesivir group (15 [3%] of 435). In patients who required high-flow oxygen at baseline, 24 (69%) of 35 had an adverse event and 21 (60%) had a serious adverse event in the interferon beta-1a plus remdesivir group compared with 13 (39%) of 33 who had an adverse event and eight (24%) who had a serious adverse event in the placebo plus remdesivir group. Interpretation Interferon beta-1a plus remdesivir was not superior to remdesivir alone in hospitalised patients with COVID-19 pneumonia. Patients who required high-flow oxygen at baseline had worse outcomes after treatment with interferon beta-1a compared with those given placebo. Funding The National Institute of Allergy and Infectious Diseases (USA).

Mycobacterium tuberculosis(Mtb), the pathological agent that causes tuberculosis (TB) is the number one infectious killer worldwide with one fourth of the world’s population currently infected. Data indicate that γ9δ2T cells secrete Granzyme A (GzmA) in the extracellular space triggering the infected monocyte to inhibit growth of intracellular mycobacteria. Accordingly, deletion ofGZMAfrom γ9δ2T cells reverses their inhibitory capacity. Through mechanistic studies, GzmA’s action was investigated in monocytes from human PBMCs. The use of recombinant human GzmA expressed in a mammalian system induced inhibition of intracellular mycobacteria to the same degree as previous human native protein findings. Our data indicate that: 1) GzmA is internalized within mycobacteria-infected cells, suggesting that GzmA uptake could prevent infection and 2) that the active site is not required to inhibit intracellular replication. Global proteomic analysis demonstrated that the ER stress response and ATP producing proteins were upregulated after GzmA treatment, and these proteins abundancies were confirmed by examining their expression in an independent set of patient samples. Our data suggest that immunotherapeutic host interventions of these pathways may contribute to better control of the current TB epidemic.

Computational surveillance of pneumonia and influenza mortality in the United States using FluView uses epidemic thresholds to identify high mortality rates but is limited by statistical issues such as seasonality and autocorrelation. We used time series anomaly detection to improve recognition of high mortality rates. Results suggest that anomaly detection can complement mortality reporting.

Failure of the most recent tuberculosis (TB) vaccine trial to boost bacillus Calmette–Guérin–mediated anti-TB immunity despite the induction of Th1-specific central memory cell and effector memory cell responses highlights the importance of identifying optimal T cell targets for protective vaccines. In this study, we describe a novel, Mycobacterium tuberculosis–specific IFN-γ+CD4+ T cell population expressing surface markers characteristic of naive-like memory T cells (TNLM), which were induced in both human (CD45RA+CCR7+CD27+CD95−) and murine (CD62L+CD44−Sca-1+CD122−) systems in response to mycobacteria. In bacillus Calmette–Guérin–vaccinated subjects and those with latent TB infection, TNLM were marked by the production of IFN-γ but not TNF-α and identified by the absence of CD95 expression and increased surface expression CCR7, CD27, the activation markers T-bet, CD69, and the survival marker CD74. Increased tetramer-positive TNLM frequencies were noted in the lung and spleen of ESAT-61–20–specific TCR transgenic mice at 2 wk postinfection with M. tuberculosis and progressively decreased at later time points, a pattern not seen with TNF-α+CD4+ T cells expressing naive cell surface markers. Importantly, adoptive transfer of highly purified TNLM alone, from vaccinated ESAT-61–20–specific TCR transgenic mice, conferred equivalent protection against M. tuberculosis infection in the lungs of Rag−/− mice when compared with total memory populations (central and effector memory cells). Thus, TNLM may represent a memory T cell population that, if optimally targeted, may significantly improve future TB vaccine responses.

Tuberculosis (TB) remains a tremendous global health problem, with 1/4 of the world's population infected and causing 1 million deaths annually. Intradermal Bacillus Calmette-Guérin (BCG) vaccine given during infancy protects against severe forms of acute disease but does not prevent chronic infection or development of pulmonary TB. TB vaccine mucosal targeting potentially could induce mucosal resident immune cells with increased protective capacity against pulmonary infection and disease. Sublingual (SL) administration of vaccines may be an optimal mucosal delivery platform based on the high absorptive capacity of this mucosal surface, the extensive lymphoid tissue, and published preclinical studies demonstrating efficacy of SL vaccination against other pathogens. To this end, we performed preliminary testing of sublingual TB vaccines. Vaccination of mice with SL BCG elicited potent mycobacteria-specific T cell responses which persisted 16 weeks post-immunization. The magnitudes of the T cell responses were similarly induced after sublingual, intranasal, and subcutaneous BCG vaccination. Interestingly, serum mycobacteria-specific antibody responses and systemic recovery of BCG post-vaccination were lower after SL BCG compared with systemic BCG immunization. However, more importantly, SL BCG vaccinated mice were significantly protected against an aerosolized virulent M. tuberculosis challenge (P 0.0001 compared to unvaccinated mice). Furthermore, this protection was long-lived, persisting for 16 weeks with1 log CFU reduction compared with naïve challenged mice in both lungs and spleens (P 0.0001 and P 0.0028, respectively). These exciting results provide strong support for further studies exploring the mechanisms of protective immunity induced by sublingual BCG vaccination.

SummaryAntigen classes other than proteins can be presented to T cells by near-monomorphic antigen-presenting molecules such as CD1, MR1, and butyrophilin 3A1. We sought to define the roles of donor unrestricted T (DURT) cells, including MR1-reactive MAIT cells, CD1b-reactive glucose monomycolate (GMM)-specific T cells, CD1d-reactive NKT cells, and γδ T cells, in vaccination against Mycobacterium tuberculosis. We characterized DURT cells following primary bacille Calmette-Guerin (BCG) vaccination in infants or BCG-revaccination in adults. BCG (re)vaccination did not modulate peripheral blood frequencies, T cell activation or memory profiles of MAIT cells, CD1b-restricted GMM-specific and germline-encoded mycolyl-reactive (GEM) cells or CD1d- restricted NKT cells. By contrast, BCG vaccination was associated with increased frequencies of γδ T cells as well as a novel subset of IFN-γ-expressing CD4+ T cells with a CD26+CD161+TRAV1-2− phenotype in infants. More studies are required to understand the full potential of DURT cells in new TB vaccine strategies.

Background Herpes zoster (HZ) infection increases dementia risk, but it is not known if herpes zoster vaccination is associated with lower risk for dementia. We determined if HZ vaccination, compared to no HZ vaccination, is associated with lower risk for incident dementia. Methods and findings Data was obtained from Veterans Health Affairs (VHA) medical records (10/1/2008–9/30/2019) with replication in MarketScan® commercial and Medicare claims (1/1/2009-12/31/2018). Eligible patients were ≥65 years of age and free of dementia for two years prior to baseline (VHA n = 136,016; MarketScan n = 172,790). Two index periods (either start of 2011 or 2012) were defined, where patients either had or did not have a HZ vaccination. Confounding was controlled with propensity scores and inverse probability of treatment weighting. Competing risk (VHA) and Cox proportional hazard (MarketScan) models estimated the association between HZ vaccination and incident dementia in all patients and in age (65–69, 70–74, ≥75) and race (White, Black, Other) sub-groups. Sensitivity analysis measured the association between HZ vaccination and incident Alzheimer’s dementia (AD). HZ vaccination at index versus no HZ vaccination throughout follow-up. VHA patients mean age was 75.7 (SD±7.4) years, 4.0% were female, 91.2% white and 20.2% had HZ vaccination. MarketScan patients mean age was 69.9 (SD±5.7) years, 65.0% were female and 14.2% had HZ vaccination. In both cohorts, HZ vaccination compared with no vaccination, was significantly associated with lower dementia risk (VHA HR = 0.69; 95%CI: 0.67–0.72; MarketScan HR = 0.65; 95%CI:0.57–0.74). HZ vaccination was not related to dementia risk in MarketScan patients aged 65–69 years. No difference in HZ vaccination to dementia effects were found by race. HZ vaccination was associated with lower risk for AD. Conclusions HZ vaccination is associated with reduced risk of dementia. Vaccination may provide nonspecific neuroprotection by training the immune system to limit damaging inflammation, or specific neuroprotection that prevents viral cytopathic effects.

Natural killer (NK) cells are an important cell subset of the innate immune system. Accumulating evidence indicates that NK cells are dysfunctional in the tumor microenvironment during cancer development. However, the dynamic changes in phenotypes and functional interactions within the tumor microenvironment during tumor development and progression are unknown. Here, we used both the mouse E0771 breast cancer and B16F0 melanoma tumor models to mimic different clinical stages of human cancers and characterized the dynamic distributions and qualities of NK cells in different organs and tumors associated with tumor progression. We found that NK cells are dynamically involved in the immune responses to cancer with different distributions and phenotypic profiles in tumor sites and other peripheral organs during the course of tumor development and progression. In the early stages of tumor development, NK cells exhibit effector properties. In the later cancer stages, NK cells have impaired cytotoxic capacities and dysfunctional states. Importantly, we found that melanoma and breast cancer cells promote NK cells to become senescent NK cells in vitro and in vivo in tumor microenvironments. These studies provide a better understanding of the dynamic and functional role of NK cells in anti-tumor immunity, which may facilitate the development of novel immunotherapies targeting NK cells for cancer treatment. the Melanoma Research Alliance, American Cancer Society, and the National Institutes of Health.

Trypanosoma cruzi is the intracellular parasite of Chagas disease, a chronic condition characterized by cardiac and gastrointestinal morbidity. Protective immunity requires CD4+ T cells, and Th1 cells and IFN-γ are important players in host defense. More recently, Th17 cells and IL-17 have been shown to exert protective functions in systemic T. cruzi infection. However, it remains unclear whether Th17 cells and IL-17A protect against mucosal infection, which is an important cause of human outbreaks. We found that IL-17RA knock-out (KO) mice are highly susceptible to orogastric infection, indicating an important function for this cytokine in mucosal immunity to T. cruzi. To investigate the specific role of Th17 cells for mucosal immunity, we reconstituted RAG1 KO mice with T. cruzi-specific T cell receptor transgenic Th17 cells prior to orogastric T. cruzi challenges. We found that Th17 cells provided protection against gastric mucosal T. cruzi infection, indicated by significantly lower stomach parasite burdens. In vitro macrophage infection assays revealed that protection by Th17 cells is reversed with IL-17A neutralization or loss of macrophage NADPH oxidase activity. Consistent with this, in vivo, mice lacking functional NADPH oxidase were not protected by Th17 cell transfer. These data are the first report that Th17 cells protect against mucosal T. cruzi infection, and identify a novel protective mechanism involving the induction of NADPH oxidase activity in macrophages by IL-17A. These studies provide important insights for Chagas vaccine development, and more broadly, increase our understanding of the diverse roles of Th17 cells in host defense.

Natural infection of SARS-CoV-2 in humans leads to the development of a strong neutralizing antibody response, however the immunodominant targets of the polyclonal neutralizing antibody response are still unknown. Here, we functionally define the role SARS-CoV-2 spike plays as a target of the human neutralizing antibody response. In this study, we identify the spike protein subunits that contain antigenic determinants and examine the neutralization capacity of polyclonal sera from a cohort of patients that tested qRT-PCR-positive for SARS-CoV-2. Using an ELISA format, we assessed binding of human sera to spike subunit 1 (S1), spike subunit 2 (S2) and the receptor binding domain (RBD) of spike. To functionally identify the key target of neutralizing antibody, we depleted sera of subunit-specific antibodies to determine the contribution of these individual subunits to the antigen-specific neutralizing antibody response. We show that epitopes within RBD are the target of a majority of the neutralizing antibodies in the human polyclonal antibody response. These data provide critical information for vaccine development and development of sensitive and specific serological testing.

Natural killer (NK) and natural killer T (NKT) cells are two important cell subsets of the innate immune system. NK and NKT cells share many phenotypes and functions for anti-tumor immunity; however, the dynamic changes in phenotypes and functional interactions within the tumor microenvironment during tumor development and progression are unknown. Here we report that NK and NKT cells have distinct properties, metabolic profiles, and functions during tumor development. Using the mouse E0771 breast cancer and B16 melanoma models, we found that both NK and NKT cells are dynamically involved in the immune responses to cancer but have distinct distributions and phenotypic profiles in tumor sites and other peripheral organs during the course of tumor development and progression. In the early stages of tumor development, both NK and NKT cells exhibit effector properties. In the later cancer stages, NK and NKT cells have impaired cytotoxic capacities and dysfunctional states. NK cells become senescent cells, while NKT cells, other than invariant NKT (iNKT) cells, are exhausted in the advanced cancers. In contrast, iNKT cells develop increases in activation and effector function within the breast tumor microenvironment. In addition, senescent NK cells have heightened glucose and lipid metabolism, but exhausted NKT cells display unbalanced metabolism in tumor microenvironments of both breast cancer and melanoma tumor models. These studies provide a better understanding of the dynamic and distinct functional roles of NK and NKT cells in anti-tumor immunity, which may facilitate the development of novel immunotherapies targeting NK and NKT cells for cancer treatment.

TH17 cells have been extensively investigated in inflammation, autoimmune diseases, and cancer. The precise molecular mechanisms for TH17 cell regulation, however, remain elusive, especially regulation at the post-transcriptional level. Tristetraprolin (TTP) is an RNA-binding protein important for degradation of the mRNAs encoding several proinflammatory cytokines. With newly generated T cell-specific TTP conditional knockout mice (CD4CreTTPf/f), we found that aging CD4CreTTPf/f mice displayed an increase of IL-17A in serum and spontaneously developed chronic skin inflammation along with increased effector TH17 cells in the affected skin. TTP inhibited TH17 cell development and function by promoting IL-17A mRNA degradation. In a DSS-induced colitis model, CD4CreTTPf/f mice displayed severe colitis and had more TH17 cells and serum IL-17A compared with wild-type mice. Furthermore, neutralization of IL-17A reduced the severity of colitis. Our results reveal a new mechanism for regulating TH17 function and TH17-mediated inflammation post-transcriptionally by TTP, suggests that TTP might be a novel therapeutic target for the treatment of TH17-mediated diseases.

Dendritic cells (DCs) are an indispensable part of studying human responses that are important for protective immunity against cancer and infectious diseases as well as prevention of autoimmunity and transplant rejection. These cells are also key elements of personalized vaccines for cancer and infectious diseases. Despite the vital role of DCs in both clinical and basic research contexts, methods for obtaining these cells from individuals remains a comparatively under-developed and inefficient process. DCs are present in very low concentrations (

A comprehensive strategy to control hepatitis C virus (HCV) infection needs a vaccine. Our phase I study with recombinant HCV E1/E2 envelope glycoprotein (EnvGPs) as a candidate vaccine did not induce a strong immune response in volunteers. We analyzed the interactions of HCV EnvGPs with human monocyte-derived macrophages as antigen-presenting cells. HCV E2 induced immune regulatory cytokine interleukin (IL)-10 and soluble CD163 (sCD163) protein expression in macrophages from 7 of 9 blood donors tested. Furthermore, HCV E2 enhanced Stat3 and suppressed Stat1 activation, reflecting macrophage polarization toward M2 phenotype. E2-associated macrophage polarization appeared to be dependent of its interaction with CD81 leading endothelial growth factor receptor (EGFR) activation. Additionally, E2 suppressed the expression of C3 complement, similar to HCV-exposed dendritic cells (DCs), implying potential impairment of immune cell priming. Conclusion: Our results suggest that E2 EnvGP may not be an ideal candidate for HCV vaccine development, and discrete domains within E2 may prove to be more capable of elliciting a protective immune response. (Hepatology 2018).

Protective efficacy of Bacillus Calmette-Guerin (BCG) may be affected by the methods and routes of vaccine administration. We have studied the safety and immunogenicity of oral (PO) and/or intradermal (ID) administration of BCG in healthy human subjects. No major safety concerns were detected in the 68 healthy adults vaccinated with PO and/or ID BCG. Although both PO and ID BCG could induce systemic Th1 responses capable of IFN-γ production, ID BCG more strongly induced systemic Th1 responses. In contrast, stronger mucosal responses (TB-specific secretory IgA and bronchoalveolar lavage T cells) were induced by PO BCG vaccination. To generate preliminary data comparing the early gene signatures induced by mucosal and systemic BCG vaccination, CD4+ memory T cells were isolated from subsets of BCG vaccinated subjects pre- (Day 0) and post-vaccination (Days 7 and 56), rested or stimulated with BCG infected dendritic cells, and then studied by Illumina BeadArray transcriptomal analysis. Notably, distinct gene expression profiles were identified both on Day 7 and Day 56 comparing the PO and ID BCG vaccinated groups by GSEA analysis. Future correlation analyses between specific gene expression patterns and distinct mucosal and systemic immune responses induced will be highly informative for TB vaccine development.

Metabolic disorder is one of the hallmarks of cancers, and reprogramming of metabolism is becoming a novel strategy for cancer treatment. Citrate is a key metabolite and critical metabolic regulator linking glycolysis and lipid metabolism in cellular energy homeostasis. Here it is reported that citrate treatment (both sodium citrate and citric acid) significantly suppresses tumor cell proliferation and growth in various tumor types. Mechanistically, citrate promotes excessive lipid biosynthesis and induces disruption of lipid metabolism in tumor cells, resulting in tumor cell senescence and growth inhibition. Furthermore, ATM‐associated DNA damage response cooperates with MAPK and mTOR signaling pathways to control citrate‐induced tumor cell growth arrest and senescence. In vivo studies further demonstrate that citrate administration dramatically inhibits tumor growth and progression in a colon cancer xenograft model. Importantly, citrate administration combined with the conventional chemotherapy drugs exhibits synergistic antitumor effects in vivo in the colon cancer models. These results clearly indicate that citrate can reprogram lipid metabolism and cell fate in cancer cells, and targeting citrate can be a promising therapeutic strategy for tumor treatment., Reprogramming of metabolism is a novel strategy for cancer treatment. Extracellular citrate administration in tumor cells induces activation of the DNA damage response, MAPK, and mTOR signaling pathways. The activated cascades further induce excessive lipid biosynthesis and provoke senescence to impair tumor cell growth in vitro and in vivo. Targeting citrate can be a promising therapeutic strategy for tumor treatment.

Objectives. To understand where transmission of Zika virus has the highest likelihood to occur in the contiguous United States with regard to its transmission both sexually and via Aedes aegypti mosquito bites. Methods. We evaluated the 2 routes of transmission risk with predictors of sexually transmitted infections (percentage women of childbearing age, birthrate, gonorrhea and chlamydia rates, concentrated disadvantage) as a surrogate for unprotected sexual activity and the demographic distribution of the A. aegypti mosquito across 3108 counties in the contiguous United States. Results. We found that 507 counties had the highest risk of virus exposure via mosquito vector or unprotected sexual activity; these were concentrated in southern states extending northward along the Atlantic coast and southern California, with the highest predicted risk in Mississippi counties. Conclusions. Identifying areas with higher transmission risk can inform prevention strategies and vector control, and assist in planning for diagnosis and treatment.

Summary Background Bacille Calmette–Guerin (BCG) is the world's most widely distributed vaccine, used against tuberculosis (TB), in cancer immunotherapy, and in autoimmune diseases due to its immunomodulatory properties. To date, the effect of BCG vaccination on antibody responses to host proteins has not been reported. High-content peptide microarrays (HCPM) offer a unique opportunity to gauge specific humoral immune responses. Methods The sera of BCG-vaccinated healthy adults were tested on a human HCPM platform (4953 randomly selected epitopes of human proteins) to detect specific immunoglobulin gamma (IgG) responses. Samples were obtained at 56, 112, and 252 days after vaccination. Immunohistology was performed on lymph node tissue from patients with TB lymphadenitis. Results were analysed with a combination of existing and novel statistical methods. Results IgG recognition of host peptides exhibited a peak at day 56 post BCG vaccination in all study subjects tested, which diminished over time. Primarily, IgG responses exhibited increased reactivity to ion transporters (sodium, calcium channels), cytokine receptors (interleukin 2 receptor β (IL2Rβ), fibroblast growth factor receptor 1 (FGFR1)), other cell surface receptors (inositol, somatostatin, angiopoeitin), ribonucleoprotein, and enzymes (tyrosine kinases, phospholipase) on day 56. There was decreased IgG reactivity to transforming growth factor-beta type 1 receptor (TGFβR1) and, in agreement with the peptide microarray findings, immunohistochemical analysis of TB-infected lymph node samples revealed an overexpression of TGFβR in granulomatous lesions. Moreover, the vesicular monoamine transporter (VMAT2) showed increased reactivity on days 112 and 252, but not on day 56 post-vaccination. IgG to interleukin 4 receptor (IL4R) showed increased reactivity at 112 days post-vaccination, while IgG to IL2Rβ and FGFR1 showed decreased reactivity on days 112 and 252 as compared to day 56 post BCG vaccination. Conclusions BCG vaccination modifies the host's immune landscape after 56 days, but this imprint changes over time. This may influence the establishment of immunological memory in BCG-vaccinated individuals.

Influenza world-wide causes significant morbidity and mortality annually, and more severe pandemics when novel strains evolve to which humans are immunologically naïve. Because of the high viral mutation rate, new vaccines must be generated based on the prevalence of circulating strains every year. New approaches to induce more broadly protective immunity are urgently needed. Previous research has demonstrated that influenza-specific T cells can provide broadly heterotypic protective immunity in both mice and humans, supporting the rationale for developing a T cell-targeted universal influenza vaccine. We used state-of-the art immunoinformatic tools to identify putative pan-HLA-DR and HLA-A2 supertype-restricted T cell epitopes highly conserved among >50 widely diverse influenza A strains (representing hemagglutinin types 1, 2, 3, 5, 7 and 9). We found influenza peptides that are highly conserved across influenza subtypes that were also predicted to be class I epitopes restricted by HLA-A2; these peptides were found to be immunoreactive in HLA-A2 positive but not HLA-A2 negative individuals. Class II-restricted T cell epitopes that were highly conserved across influenza subtypes were identified. Human CD4(+) T cells were reactive with these conserved CD4 epitopes, and epitope expanded T cells were responsive to both H1N1 and H3N2 viruses. Dendritic cell vaccines pulsed with conserved epitopes and DNA vaccines encoding these epitopes were developed and tested in HLA transgenic mice. These vaccines were highly immunogenic, and more importantly, vaccine-induced immunity was protective against both H1N1 and H3N2 influenza challenges. These results demonstrate proof-of-principle that conserved T cell epitopes expressed by widely diverse influenza strains can induce broadly protective, heterotypic influenza immunity, providing strong support for further development of universally relevant multi-epitope T cell-targeting influenza vaccines.

Failure of the most recent tuberculosis (TB) vaccine trial to boost bacillus Calmette-Guérin-mediated anti-TB immunity despite the induction of Th1-specific central memory cell and effector memory cell responses highlights the importance of identifying optimal T cell targets for protective vaccines. In this study, we describe a novel

The dimerization of 70S ribosomes (100S complex) plays an important role in translational regulation and infectivity of the major human pathogen Staphylococcus aureus. Although the dimerizing factor HPF has been characterized biochemically, the pathways that regulate 100S ribosome abundance remain elusive. We identified a metabolite- and nutrient-sensing transcription factor, CodY, that serves both as an activator and a repressor of hpf expression in nutrient- and temperature-dependent manners. Furthermore, CodY-mediated activation of hpf masks a secondary hpf transcript derived from a general stress response SigB promoter. CodY and SigB regulate a repertoire of virulence genes. The unexpected link between ribosome homeostasis and the two master virulence regulators provides new opportunities for alternative druggable sites., The translationally silent 100S ribosome is a poorly understood form of the dimeric 70S complex that is ubiquitously found in all bacterial phyla. The elimination of the hibernating 100S ribosome leads to translational derepression, ribosome instability, antibiotic sensitivity, and biofilm defects in some bacteria. In Firmicutes, such as the opportunistic pathogen Staphylococcus aureus, a 190-amino acid protein called hibernating-promoting factor (HPF) dimerizes and conjoins two 70S ribosomes through a direct interaction between the HPF homodimer, with each HPF monomer tethered on an individual 70S complex. While the formation of the 100S ribosome in gammaproteobacteria and cyanobacteria is exclusively induced during postexponential growth phase and darkness, respectively, the 100S ribosomes in Firmicutes are constitutively produced from the lag-logarithmic phase through the post-stationary phase. Very little is known about the regulatory pathways that control hpf expression and 100S ribosome abundance. Here, we show that a general stress response (GSR) sigma factor (SigB) and a GTP-sensing transcription factor (CodY) integrate nutrient and thermal signals to regulate hpf synthesis in S. aureus, resulting in an enhanced virulence of the pathogen in a mouse model of septicemic infection. CodY-dependent regulation of hpf is strain specific. An epistasis analysis further demonstrated that CodY functions upstream of the GSR pathway in a condition-dependent manner. The results reveal an important link between S. aureus stress physiology, ribosome metabolism, and infection biology. IMPORTANCE The dimerization of 70S ribosomes (100S complex) plays an important role in translational regulation and infectivity of the major human pathogen Staphylococcus aureus. Although the dimerizing factor HPF has been characterized biochemically, the pathways that regulate 100S ribosome abundance remain elusive. We identified a metabolite- and nutrient-sensing transcription factor, CodY, that serves both as an activator and a repressor of hpf expression in nutrient- and temperature-dependent manners. Furthermore, CodY-mediated activation of hpf masks a secondary hpf transcript derived from a general stress response SigB promoter. CodY and SigB regulate a repertoire of virulence genes. The unexpected link between ribosome homeostasis and the two master virulence regulators provides new opportunities for alternative druggable sites.