Senataxin suppresses the antiviral transcriptional response and controls viral biogenesis.

The human helicase senataxin (SETX) has been linked to the neurodegenerative diseases amyotrophic lateral sclerosis (ALS4) and ataxia with oculomotor apraxia (AOA2). Here we identified a role for SETX in controlling the antiviral response. Cells that had undergone depletion of SETX and SETX-deficient cells derived from patients with AOA2 had higher expression of antiviral mediators in response to infection than did wild-type cells. Mechanistically, we propose a model whereby SETX attenuates the activity of RNA polymerase II (RNAPII) at genes stimulated after a virus is sensed and thus controls the magnitude of the host response to pathogens and the biogenesis of various RNA viruses (e.g., influenza A virus and West Nile virus). Our data indicate a potentially causal link among inborn errors in SETX, susceptibility to infection and the development of neurologic disorders.

Unanchored K48-linked polyubiquitin synthesized by the E3-ubiquitin ligase TRIM6 stimulates the interferon-IKKε kinase-mediated antiviral response.

Type I interferons (IFN-I) are essential antiviral cytokines produced upon microbial infection. IFN-I elicits this activity through the upregulation of hundreds of IFN-I-stimulated genes (ISGs). The full breadth of ISG induction demands activation of a number of cellular factors including the IκB kinase epsilon (IKKε). However, the mechanism of IKKε activation upon IFN receptor signaling has remained elusive. Here we show that TRIM6, a member of the E3-ubiquitin ligase tripartite motif (TRIM) family of proteins, interacted with IKKε and promoted induction of IKKε-dependent ISGs. TRIM6 and the E2-ubiquitin conjugase UbE2K cooperated in the synthesis of unanchored K48-linked polyubiquitin chains, which activated IKKε for subsequent STAT1 phosphorylation. Our work attributes a previously unrecognized activating role of K48-linked unanchored polyubiquitin chains in kinase activation and identifies the UbE2K-TRIM6-ubiquitin axis as critical for IFN signaling and antiviral response.

Major bleeding in patients with pulmonary embolism presenting with syncope.

INTRODUCTION: Syncope has been shown to be a risk factor of bleeding in patients receiving thrombolytic therapy for acute pulmonary embolism (PE). Whether syncope predicts bleeding in a broader population of patients with PE remains unknown. METHODS: We used the RIETE registry data to assess whether initial presentation with syncope could predict bleeding in PE patients receiving anticoagulant therapy, and to explore the association between presence of syncope and timing and site of major bleeding events. RESULTS: Among 45,765 patients with acute PE from March 2001 to January 2021, 6760 (14.8%) had syncope. Patients with syncope were older and more likely to have hypotension, tachycardia, hypoxaemia or elevated troponin levels than those without syncope. They also were more likely to receive thrombolytics. During the first 90 days, 1097 patients (2.4%) suffered major bleeding (gastrointestinal 335, hematoma 271 and intracranial 163) and 3611 died (158 had fatal bleeding). Patients with syncope had a higher rate of major bleeding (odds ratio [OR]: 1.63; 95% CI: 1.41-1.89) and a nonsignificantly higher rate of fatal bleeding (OR: 1.47; 95% CI: 0.99-2.17) than those without syncope. Multivariable analysis confirmed that patients with syncope were at increased risk for major bleeding (adjusted hazard ratio [aHR]: 1.34; 95% CI: 1.15-1.55). On sensitivity analysis, the increased risk for major bleeding was confirmed in patients initially receiving anticoagulant therapy without thrombolytics at 7 days (aHR: 1.47; 95% CI: 1.13-1.91) and 90 days (aHR: 1.33; 95%CI: 1.13-1.56). DISCUSSION: Syncope is a predictor of major bleeding events in patients with PE, even among those receiving anticoagulation monotherapy.

Antithrombotic therapy and clinical outcomes at 1 year in the Spanish cohort of the EORP-AF Long-term General Registry.

BACKGROUND: Atrial fibrillation (AF) increases the risk of thromboembolism. We investigate the efficacy and safety of oral anticoagulation (OAC) therapy and explored the number needed to treat for net effect (NNTnet) of OAC in the Spanish cohort of the EURObservational Research Programme-AF (EORP-AF) Long-term General Registry. METHODS: The EORP-AF General Registry is a prospective, multicentre registry conducted in ESC countries, including consecutive AF patients. For the present analysis, we used the Spanish cohort, and the primary outcome was any thromboembolism (TE)/acute coronary syndrome (ACS)/cardiovascular death during the first year of follow-up. RESULTS: 729 AF patients were included (57.1% male, median age 75 [IQR 67-81] years, median CHA2 DS2 -VASc and HAS-BLED of 3 [IQR 2-5] and 2 [IQR 1-2], respectively). 548 (75.2%) patients received OAC alone (318 [43.6%] on VKAs and 230 [31.6%] on DOACs). After 1 year, the use of OAC alone showed lower rates of any TE/ACS/cardiovascular death (3.0%/year; p < 0.001) compared to other regimens, and non-use of OAC alone (HR 4.18, 95% CI 2.12-8.27) was independently associated with any TE/ACS/cardiovascular death. Balancing the effects of treatment, the NNTnet to provide an overall benefit of OAC therapy was 24. The proportion of patients on OAC increased at 1 year (87% to 88.1%), particularly on DOACs (33.6% to 39.9%) (p = 0.015), with low discontinuation rates. CONCLUSIONS: In this contemporary cohort of AF patients, OAC therapy was associated with better clinical outcomes at 1 year and positive NNTnet. OAC use slightly increased during the follow-up, with low discontinuation rates and higher prescription of DOACs.

The E3-ligase TRIM family of proteins regulates signaling pathways triggered by innate immune pattern-recognition receptors.

Innate immunity conferred by the type I interferon is critical for antiviral defense. To date only a limited number of tripartite motif (TRIM) proteins have been implicated in modulation of innate immunity and anti-microbial activity. Here we report the complementary DNA cloning and systematic analysis of all known 75 human TRIMs. We demonstrate that roughly half of the 75 TRIM-family members enhanced the innate immune response and that they do this at multiple levels in signaling pathways. Moreover, messenger RNA levels and localization of most of these TRIMs were found to be altered during viral infection, suggesting that their regulatory activities are highly controlled at both pre- and posttranscriptional levels. Taken together, our data demonstrate a very considerable dedication of this large protein family to the positive regulation of the antiviral response, which supports the notion that this family of proteins evolved as a component of innate immunity.

Clinical characteristics and 3-month outcomes in cancer patients with incidental versus clinically suspected and confirmed pulmonary embolism.

BACKGROUND: Current guidelines suggest treating cancer patients with incidental pulmonary embolism (PE) similarly to those with clinically suspected and confirmed PE. However, the natural history of these presentations has not been thoroughly compared. METHODS: We used the data from the RIETE (Registro Informatizado de Enfermedad TromboEmbólica) registry to compare the 3-month outcomes in patients with active cancer and incidental PE versus those with clinically suspected and confirmed PE. The primary outcome was 90-day all-cause mortality. Secondary outcomes were PE-related mortality, symptomatic PE recurrences and major bleeding. RESULTS: From July 2012 to January 2019, 946 cancer patients with incidental asymptomatic PE and 2274 with clinically suspected and confirmed PE were enrolled. Most patients (95% versus 90%) received low-molecular-weight heparin therapy. During the first 90 days, 598 patients died, including 42 from PE. Patients with incidental PE had a lower all-cause mortality rate than those with suspected and confirmed PE (11% versus 22%; OR 0.43, 95% CI 0.34-0.54). Results were consistent for PE-related mortality (0.3% versus 1.7%; OR 0.18, 95% CI 0.06-0.59). Multivariable analysis confirmed that patients with incidental PE were at lower risk of death (adjusted OR 0.43, 95% CI 0.34-0.56). Overall, 29 (0.9%) patients developed symptomatic PE recurrences, and 122 (3.8%) had major bleeding. There were no significant differences in PE recurrences (OR 0.62, 95% CI 0.25-1.54) or major bleeding (OR 0.78, 95% CI 0.51-1.18). CONCLUSIONS: Cancer patients with incidental PE had a lower mortality rate than those with clinically suspected and confirmed PE. Further studies are required to validate these findings, and to explore optimal management strategies in these patients.

Derivation and validation of a clinical prediction rule for thrombolysis-associated major bleeding in patients with acute pulmonary embolism: the BACS score.

BACKGROUND: Improved prediction of the risk of major bleeding in patients with acute pulmonary embolism (PE) receiving systemic thrombolysis is crucial to guide the choice of therapy. METHODS: The study included consecutive patients with acute PE who received systemic thrombolysis in the RIETE registry. We used multivariable logistic regression analysis to create a risk score to predict 30-day major bleeding episodes. We externally validated the risk score in patients from the COMMAND VTE registry. We also compared the newly created risk score against the Kuijer and RIETE scores. RESULTS: Multivariable logistic regression identified four predictors for major bleeding: recent major Bleeding (3 points), Age >75 years (1 point), active Cancer (1 point), and Syncope (1 point) (BACS). Among 1172 patients receiving thrombolytic therapy in RIETE, 446 (38%) were classified as having low-risk (none of the variables present, 0 points) of major bleeding according to the BACS score, and the overall 30-day major bleeding rate of this group was 2.9% (95% CI, 1.6-4.9%), compared with 44% (95% CI, 14-79%) in the high-risk group (>3 points). In the validation cohort, 51% (149/290) of patients were classified as having low-risk, and the overall 30-day major bleeding rate of this group was 1.3%. In RIETE, the 30-day major bleeding event rates in the Kuijer and RIETE low-risk stratum were 5.3% and 4.4%, respectively. CONCLUSIONS: The BACS score is an easily applicable aid for prediction of the risk of major bleeding in the population of PE patients who receive systemic thrombolysis.

Dengue virus genomic variation associated with mosquito adaptation defines the pattern of viral non-coding RNAs and fitness in human cells.

The Flavivirus genus includes a large number of medically relevant pathogens that cycle between humans and arthropods. This host alternation imposes a selective pressure on the viral population. Here, we found that dengue virus, the most important viral human pathogen transmitted by insects, evolved a mechanism to differentially regulate the production of viral non-coding RNAs in mosquitos and humans, with a significant impact on viral fitness in each host. Flavivirus infections accumulate non-coding RNAs derived from the viral 3'UTRs (known as sfRNAs), relevant in viral pathogenesis and immune evasion. We found that dengue virus host adaptation leads to the accumulation of different species of sfRNAs in vertebrate and invertebrate cells. This process does not depend on differences in the host machinery; but it was found to be dependent on the selection of specific mutations in the viral 3'UTR. Dissecting the viral population and studying phenotypes of cloned variants, the molecular determinants for the switch in the sfRNA pattern during host change were mapped to a single RNA structure. Point mutations selected in mosquito cells were sufficient to change the pattern of sfRNAs, induce higher type I interferon responses and reduce viral fitness in human cells, explaining the rapid clearance of certain viral variants after host change. In addition, using epidemic and pre-epidemic Zika viruses, similar patterns of sfRNAs were observed in mosquito and human infected cells, but they were different from those observed during dengue virus infections, indicating that distinct selective pressures act on the 3'UTR of these closely related viruses. In summary, we present a novel mechanism by which dengue virus evolved an RNA structure that is under strong selective pressure in the two hosts, as regulator of non-coding RNA accumulation and viral fitness. This work provides new ideas about the impact of host adaptation on the variability and evolution of flavivirus 3'UTRs with possible implications in virulence and viral transmission.

A novel Zika virus mouse model reveals strain specific differences in virus pathogenesis and host inflammatory immune responses.

Zika virus (ZIKV) is a mosquito borne flavivirus, which was a neglected tropical pathogen until it emerged and spread across the Pacific Area and the Americas, causing large human outbreaks associated with fetal abnormalities and neurological disease in adults. The factors that contributed to the emergence, spread and change in pathogenesis of ZIKV are not understood. We previously reported that ZIKV evades cellular antiviral responses by targeting STAT2 for degradation in human cells. In this study, we demonstrate that Stat2-/- mice are highly susceptible to ZIKV infection, recapitulate virus spread to the central nervous system (CNS), gonads and other visceral organs, and display neurological symptoms. Further, we exploit this model to compare ZIKV pathogenesis caused by a panel of ZIKV strains of a range of spatiotemporal history of isolation and representing African and Asian lineages. We observed that African ZIKV strains induce short episodes of severe neurological symptoms followed by lethality. In comparison, Asian strains manifest prolonged signs of neuronal malfunctions, occasionally causing death of the Stat2-/- mice. African ZIKV strains induced higher levels of inflammatory cytokines and markers associated with cellular infiltration in the infected brain in mice, which may explain exacerbated pathogenesis in comparison to those of the Asian lineage. Interestingly, viral RNA levels in different organs did not correlate with the pathogenicity of the different strains. Taken together, we have established a new murine model that supports ZIKV infection and demonstrate its utility in highlighting intrinsic differences in the inflammatory response induced by different ZIKV strains leading to severity of disease. This study paves the way for the future interrogation of strain-specific changes in the ZIKV genome and their contribution to viral pathogenesis.

Antagonism of type I interferon by flaviviruses.

The prompt and tightly controlled induction of type I interferon is a central event of the immune defense against viral infection. Flaviviruses comprise a large family of arthropod-borne positive-stranded RNA viruses, many of which represent a serious threat to global human health due to their high rates of morbidity and mortality. All flaviviruses studied so far have been shown to counteract the host's immune response to establish a productive infection and facilitate viral spread. Here, we review the current knowledge on the main strategies that human pathogenic flaviviruses utilize to escape both type I IFN induction and effector pathways. A better understanding of the specific mechanisms by which flaviviruses activate and evade innate immune responses is critical for the development of better therapeutics and vaccines.

Outcome during and after anticoagulant therapy in cancer patients with incidentally found pulmonary embolism.

Current guidelines suggest treating cancer patients with incidental pulmonary embolism comparably to patients with symptomatic pulmonary embolism.We used the Registro Informatizado de Enfermedad TromboEmbólica (RIETE) registry to compare the rate of major bleeding and symptomatic pulmonary embolism during the course of anticoagulation and after its discontinuation in cancer patients with incidental pulmonary embolism.As of March 2016, 715 cancer patients with incidental pulmonary embolism had been enrolled in RIETE. During the course of anticoagulant therapy (mean 235 days), the rate of major bleeding was higher than the rate of symptomatic pulmonary embolism (10.1 (95% CI 7.48-13.4) versus 3.17 (95% CI 1.80-5.19) events per 100 patient-years, respectively), and the rate of fatal bleeding was higher than the rate of fatal pulmonary embolism (2.66 (95% CI 1.44-4.52) versus 0.66 (95% CI 0.17-1.81) deaths per 100 patient-years, respectively). After discontinuing anticoagulation (mean follow-up 117 days), the rate of major bleeding was lower than the rate of symptomatic pulmonary embolism (3.00 (95% CI 1.10-6.65) versus 8.37 (95% CI 4.76-13.7) events per 100 patient-years, respectively); however, there were no differences in the rate of fatal events at one death each.The risk/benefit ratio of anticoagulant therapy in cancer patients with incidental pulmonary embolism is uncertain and must be evaluated in further studies.

HIV Vpu Interferes with NF-κB Activity but Not with Interferon Regulatory Factor 3.

UNLABELLED: The accessory HIV protein Vpu inhibits a number of cellular pathways that trigger host innate restriction mechanisms. HIV Vpu-mediated degradation of tetherin allows efficient particle release and hampers the activation of the NF-κB pathway thereby limiting the expression of proinflammatory genes. In addition, Vpu reduces cell surface expression of several cellular molecules such as newly synthesized CD4. However, the role of HIV Vpu in regulating the type 1 interferon response to viral infection by degradation of the interferon regulatory factor 3 (IRF3) has been subject of conflicting reports. We therefore systematically investigated the expression of IRF3 in primary CD4(+) T cells and macrophages infected with HIV at different time points. In addition, we also tested the ability of Vpu to interfere with innate immune signaling pathways such as the NF-κB and the IRF3 pathways. We report here that HIV Vpu failed to degrade IRF3 in infected primary cells. Moreover, we observed that HIV NL4.3 Vpu had no effect on IRF3-dependent gene expression in reporter assays. On the other hand, HIV NL4.3 Vpu downmodulated NF-κB-dependent transcription. Mutation of two serines (positions 52 and 56) involved in the binding of NL4.3 Vpu to the ßTrCP ubiquitin ligase abolishes its ability to inhibit NF-κB activity. Taken together, these results suggest that HIV Vpu regulates antiviral innate response in primary human cells by acting specifically on the NF-κB pathway. IMPORTANCE: HIV Vpu plays a pivotal role in enhancing HIV infection by counteraction of Tetherin. However, Vpu also regulates host response to HIV infection by hampering the type 1 interferon response. The molecular mechanism by which Vpu inhibits the interferon response is still controversial. Here we report that Vpu affects interferon expression by inhibiting NF-κB activity without affecting IRF3 levels or activity. These data suggest that Vpu facilitates HIV infection by regulating NF-κB transcription to levels sufficient for viral transcription while limiting cellular responses to infection.

Dengue virus co-opts UBR4 to degrade STAT2 and antagonize type I interferon signaling.

An estimated 50 million dengue virus (DENV) infections occur annually and more than forty percent of the human population is currently at risk of developing dengue fever (DF) or dengue hemorrhagic fever (DHF). Despite the prevalence and potential severity of DF and DHF, there are no approved vaccines or antiviral therapeutics available. An improved understanding of DENV immune evasion is pivotal for the rational development of anti-DENV therapeutics. Antagonism of type I interferon (IFN-I) signaling is a crucial mechanism of DENV immune evasion. DENV NS5 protein inhibits IFN-I signaling by mediating proteasome-dependent STAT2 degradation. Only proteolytically-processed NS5 can efficiently mediate STAT2 degradation, though both unprocessed and processed NS5 bind STAT2. Here we identify UBR4, a 600-kDa member of the N-recognin family, as an interacting partner of DENV NS5 that preferentially binds to processed NS5. Our results also demonstrate that DENV NS5 bridges STAT2 and UBR4. Furthermore, we show that UBR4 promotes DENV-mediated STAT2 degradation, and most importantly, that UBR4 is necessary for efficient viral replication in IFN-I competent cells. Our data underscore the importance of NS5-mediated STAT2 degradation in DENV replication and identify UBR4 as a host protein that is specifically exploited by DENV to inhibit IFN-I signaling via STAT2 degradation.

DENV inhibits type I IFN production in infected cells by cleaving human STING.

Dengue virus (DENV) is a pathogen with a high impact on human health. It replicates in a wide range of cells involved in the immune response. To efficiently infect humans, DENV must evade or inhibit fundamental elements of the innate immune system, namely the type I interferon response. DENV circumvents the host immune response by expressing proteins that antagonize the cellular innate immunity. We have recently documented the inhibition of type I IFN production by the proteolytic activity of DENV NS2B3 protease complex in human monocyte derived dendritic cells (MDDCs). In the present report we identify the human adaptor molecule STING as a target of the NS2B3 protease complex. We characterize the mechanism of inhibition of type I IFN production in primary human MDDCs by this viral factor. Using different human and mouse primary cells lacking STING, we show enhanced DENV replication. Conversely, mutated versions of STING that cannot be cleaved by the DENV NS2B3 protease induced higher levels of type I IFN after infection with DENV. Additionally, we show that DENV NS2B3 is not able to degrade the mouse version of STING, a phenomenon that severely restricts the replication of DENV in mouse cells, suggesting that STING plays a key role in the inhibition of DENV infection and spread in mice.

Assessment of Spanish Food Consumption Patterns during COVID-19 Home Confinement.

People's eating habits and lifestyle can have a negative impact on health. In situations of difficulty or socioeconomic crisis, these habits tend to be modified, leading to unhealthy dietary patterns that result in an increase of chronic non-communicable diseases (NCDs). Previous studies have indicated that, due to the state of alarm imposed in Spain to combat the spread of COVID-19, an increase in the purchase of non-core products occurred, along with a decrease in the daily physical activity of the population. This could be a risk factor for COVID-19 infection. The objective of this observational study was to analyze the dietary pattern of the Spanish population during home confinement and to compare it with the pattern of habitual consumption collected in the last National Health Survey, analyzing the possible changes. More than half of the respondents in the sample increased their consumption of sweets and snacks during confinement, while the consumption of fresh products decreased. Most claimed to be emotionally hungry, leading to an increase in their daily energy intake. The stress and anxiety generated by confinement could be the cause of the increased consumption of products rich in sugars and saturated fats, which are associated with greater stress and anxiety.

Comparison of seven prognostic tools to identify low-risk pulmonary embolism in patients aged <50 years.

In young patients with acute pulmonary embolism (PE), the predictive value of currently available prognostic tools has not been evaluated. Our objective was to compare prognostic value of 7 available tools (GPS, PESI, sPESI, Prognostic Algorithm, PREP, shock index and RIETE) in patients aged <50 years. We used the RIETE database, including PE patients from 2001 to 2017. The major outcome was 30-day all-cause mortality. Of 34,651 patients with acute PE, 5,822 (17%) were aged <50 years. Of these, 83 (1.4%) died during the first 30 days. Number of patients deemed low risk with tools was: PREP (95.9%), GPS (89.6%), PESI (87.2%), Shock index (70.9%), sPESI (59.4%), Prognostic algorithm (58%) and RIETE score (48.6%). The tools with a highest sensitivity were: Prognostic Algorithm (91.6%; 95% CI: 85.6-97.5), RIETE score (90.4%; 95%CI: 84.0-96.7) and sPESI (88%; 95% CI: 81-95). The RIETE, Prognostic Algorithm and sPESI scores obtained the highest overall sensitivity estimates for also predicting 7- and 90-day all-cause mortality, 30-day PE-related mortality, 30-day major bleeding and 30-day VTE recurrences. The proportion of low-risk patients who died within the first 30 days was lowest using the Prognostic Algorithm (0.2%), RIETE (0.3%) or sPESI (0.3%) scores. In PE patients less 50 years, 30-day mortality was low. Although sPESI, RIETE and Prognostic Algorithm scores were the most sensitive tools to identify patients at low risk to die, other tools should be evaluated in this population to obtain more efficient results.

Clinical Characteristics and Outcomes of Patients with Lung Cancer and Venous Thromboembolism.

Background The natural history of patients with lung cancer and venous thromboembolism (VTE) has not been consistently evaluated. Methods We used the RIETE (Registro Informatizado Enfermedad TromboEmbólica) database to assess the clinical characteristics, time course, and outcomes during anticoagulation of lung cancer patients with acute, symptomatic VTE. Results As of May 2017, a total of 1,725 patients were recruited: 1,208 (70%) presented with pulmonary embolism (PE) and 517 with deep vein thrombosis (DVT). Overall, 865 patients (50%) were diagnosed with cancer <3 months before, 1,270 (74%) had metastases, and 1,250 (72%) had no additional risk factors for VTE. During anticoagulation (median, 93 days), 166 patients had symptomatic VTE recurrences (recurrent DVT: 86, PE: 80), 63 had major bleeding (intracranial 11), and 870 died. The recurrence rate was twofold higher than the major bleeding rate during the first month, and over threefold higher beyond the first month. Fifty-seven patients died of PE and 15 died of bleeding. Most fatal PEs (84%) and most fatal bleeds (67%) occurred within the first month of therapy. Nine patients with fatal PE (16%) died within the first 24 hours. Of 72 patients dying of PE or bleeding, 15 (21%) had no metastases and 29 (40%) had the VTE shortly after surgery or immobility. Conclusion Active surveillance on early signs and/or symptoms of VTE in patients with recently diagnosed lung cancer and prescription of prophylaxis in those undergoing surgery or during periods of immobilization might likely help prevent VTE better, detect it earlier, and treat it more efficiently.

Cancer-Associated Thrombosis: Beyond Clinical Practice Guidelines-A Multidisciplinary (SEMI-SEOM-SETH) Expert Consensus.

Despite the growing interest and improved knowledge about venous thromboembolism in cancer patients in the last years, there are still many unsolved issues. Due to the limitations of the available literature, evidence-based clinical practice guidelines are not able to give solid recommendations for challenging scenarios often present in the setting of cancer-associated thrombosis (CAT). A multidisciplinary expert panel from three scientific societies-Spanish Society of Internal Medicine (SEMI), Spanish Society of Medical Oncology (SEOM), and Spanish Society Thrombosis and Haemostasis (SETH)-agreed on 12 controversial questions regarding prevention and management of CAT, which were thoroughly reviewed to provide further guidance. The suggestions presented herein may facilitate clinical decisions in specific complex circumstances, until these can be made leaning on reliable scientific evidence.

High-dimensional CyTOF analysis of dengue virus-infected human DCs reveals distinct viral signatures.

Dengue virus (DENV) is the most prevalent mosquito-borne virus causing human disease. Of the 4 DENV serotypes, epidemiological data suggest that DENV-2 secondary infections are associated with more severe disease than DENV-4 infections. Mass cytometry by time-of-flight (CyTOF) was used to dissect immune changes induced by DENV-2 and DENV-4 in human DCs, the initial targets of primary infections that likely affect infection outcomes. Strikingly, DENV-4 replication peaked earlier and promoted stronger innate immune responses, with increased expression of DC activation and migration markers and increased cytokine production, compared with DENV-2. In addition, infected DCs produced higher levels of inflammatory cytokines compared with bystander DCs, which mainly produced IFN-induced cytokines. These high-dimensional analyses during DENV-2 and DENV-4 infections revealed distinct viral signatures marked by different replication strategies and antiviral innate immune induction in DCs, which may result in different viral fitness, transmission, and pathogenesis.