A murine model of DC-SIGN humanization exhibits increased susceptibility against SARS-CoV-2.

To generate a new murine model for virus, DC-SIGN gene in murine was humanized. In this study, we successfully generated a humanized C57BL/6N mouse model expressing human DC-SIGN (hDC-SIGN) using CRISPR/Cas9 technology, and evaluated its characters and susceptibility to virus. The humanized mice could survival as usual, and with normal physiological index just like the wild-type mice. Whereas, we found significant differences in the intestinal flora and metabolic profiles between wild-type mice and humanized mice. Following intranasal infection with SARS-CoV-2, hDC-SIGN mice exhibited significantly increased viral loads in the lungs and nasal turbinates, along with more severe lung damage. This phenomenon may be associated with differential lipid metabolism and Fcγ receptor-mediated phagocytosis in two mouse models. This study provides a useful tool for investigating the mechanisms of coronavirus infection and potential drug therapies against novel coronavirus.

An omicron-based vaccine booster elicits potent neutralizing antibodies against emerging SARS-CoV-2 variants in adults.

SARS-CoV-2 Omicron subvariants have become the predominantly strain in most countries. However, the neutralizing activity of the human serum after Omicron-based vaccine booster against different SARS-CoV-2 variants is poorly understood. Here, we developed an update Omicron vaccine (SCoK-Omicron), based on the RBD-Fc fusion protein vaccine (SCoK) and RBD domain of Omicron BA.1. To assess cross-variant neutralizing activity in adults, 25 volunteers that have received three doses of SCoK and 25 volunteers with two doses of CoronaVac (inactive vaccine) were further boosted with a dose updated vaccine (SCoK-Omicron). The results of pseudovirus neutralization assays demonstrated that the booster potently induced the high-level of neutralizing antibody against SARS-CoV-2 Wild type, Delta and Omicron subvariants in adults. Further assays of single point mutations showed that K444T, L452R, N460K, or F486V was key mutations to cause immune evasion. Together, these data suggest that SCOK-Omicron can be used as a booster vaccine candidate in adults receiving subunit protein or inactivated vaccine in response to the epidemic of COVID-19 Omicron subvariants, and the mutation K444T, L452R, N460K, or F486V needs to be considered in future vaccine design.

Acinetobacter baumannii adaptation to the host pH microenvironment is mediated by allelic variation in a single residue of BauA protein.

Acinetobacter baumannii has been listed as one of the most critical pathogens in nosocomial infections; however, the key genes and mechanisms to adapt to the host microenvironment lack in-depth understanding. In this study, a total of 76 isolates (from 8 to 12 isolates per patient, spanning 128 to 188 days) were longitudinally collected from eight patients to investigate the within-host evolution of A. baumannii. A total of 70 within-host mutations were identified, 80% of which were nonsynonymous, indicating the important role of positive selection. Several evolutionary strategies of A. baumannii to increase its potential to adapt to the host microenvironment were identified, including hypermutation and recombination. Six genes were mutated in isolates from two or more patients, including two TonB-dependent receptor genes (bauA and BJAB07104_RS00665). In particular, the siderophore receptor gene bauA was mutated in multiple isolates from four patients with three MLST types, and all mutations were at amino acid 391 in ligand-binding sites. With 391T or 391A, BauA was more strongly bound to siderophores, which promoted the iron-absorption activity of A. baumannii at acidic or neutral pH, respectively. Through the A/T mutation at site 391 of BauA, A. baumannii displayed two reversible phases to adapt to distinct pH microenvironments. In conclusion, we demonstrated the comprehensive within-host evolutionary dynamics of A. baumannii, and discovered a key mutation of BauA site 391 as a genetic switch to adapt to different pH values, which may represent a model in the pathogen evolutionary adaption of the host microenvironment.

A randomized, double-blind, placebo-controlled phase 1 and phase 2 clinical trial to evaluate efficacy and safety of a SARS-CoV-2 vaccine SCoK in adults.

BACKGROUND: To determine an appropriate dose of, and immunization schedule for, a vaccine SCoK against COVID-19 for an efficacy study; herein, we conducted randomized controlled trials to assess the immunogenicity and safety of this vaccine in adults. METHODS: These randomized, double-blind, placebo-controlled phase 1 and 2 trials of vaccine SCoK were conducted in Binhai District, Yan City, Jiangsu Province, China. Younger and older adult participants in phase 1 and 2 trials were sequentially recruited into different groups to be intramuscularly administered 20 or 40 µg vaccine SCoK or placebo. Participants were enrolled into our phase 1 and 2 studies to receive vaccine or placebo. RESULTS: No serious vaccine-related adverse events were observed in either trial. In both trials, local and systemic adverse reactions were absent or mild in most participants. In our phase 1 and 2 studies, the vaccine induced significantly increased neutralizing antibody responses to pseudovirus and live SARS-CoV-2. The vaccine induced significant neutralizing antibody responses to live SARS-CoV-2 on day 14 after the last immunization, with NT50s of 80.45 and 92.46 in participants receiving 20 and 40 µg doses, respectively; the seroconversion rates were 95.83% and 100%. The vaccine SCoK showed a similar safety and immunogenicity profiles in both younger participants and older participants. The vaccine showed better immunogenicity in phase 2 than in phase 1 clinical trial. Additionally, the incidence of adverse reactions decreased significantly in phase 2 clinical trial. The vaccine SCoK was well tolerated and immunogenic.

Proteomic and Metabolomic Characterization of SARS-CoV-2-Infected Cynomolgus Macaque at Early Stage.

Although tremendous effort has been exerted to elucidate the pathogenesis of severe COVID-19 cases, the detailed mechanism of moderate cases, which accounts for 90% of all patients, remains unclear yet, partly limited by lacking the biopsy tissues. Here, we established the COVID-19 infection model in cynomolgus macaques (CMs), monitored the clinical and pathological features, and analyzed underlying pathogenic mechanisms at early infection stage by performing proteomic and metabolomic profiling of lung tissues and sera samples from COVID-19 CMs models. Our data demonstrated that innate immune response, neutrophile and platelet activation were mainly dysregulated in COVID-19 CMs. The symptom of neutrophilia, lymphopenia and massive "cytokines storm", main features of severe COVID-19 patients, were greatly weakened in most of the challenged CMs, which are more semblable as moderate patients. Thus, COVID-19 model in CMs is rational to understand the pathogenesis of moderate COVID-19 and may be a candidate model to assess the safety and efficacy of therapeutics and vaccines against SARS-CoV-2 infection.

Prognostic and Clinical Significance of COX-2 Overexpression in Laryngeal Cancer: A Meta-Analysis.

Objective: Several studies were conducted to explore the clinical significance of cyclooxygenase-2 (COX-2) overexpression in laryngeal cancer. However, the associations between COX-2 overexpression and clinicopathological characteristics of laryngeal cancer patients remained unclear. Here, we performed a meta-analysis to eva-TY -40luate the role of COX-2 overexpression in the risk, clinical progression, and progno\sis of laryngeal cancer. Methods: The eligible literature was obtained from PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI) databases. Odds ratio (OR), risk ratio (RR), and 95% confidence interval (CI) were calculated to assess the strength of the associations, and I 2 statistics were used to evaluate heterogeneity among studies. Publication bias was detected with Begg's test and Egger's test. Results: A total of 47 eligible articles were included for the meta-analysis after screening. COX-2 expression levels in the laryngeal cancer patients were significantly higher than those in the normal controls (OR = 11.62, 95% CI: 6.96-19.40, P < 0.05). The pooled results also showed that there were significant correlations between COX-2 overexpression and clinicopathological characteristics (tumor stage, OR = 3.26, 95% CI: 2.13-4.98, P < 0.05; lymph node metastasis, in Asians, OR = 2.35, 95% CI: 1.53-3.60, P < 0.05; recurrence, OR = 10.71, 95% CI: 3.54-32.38, P < 0.05; T stage, in Asians, OR = 2.52, 95% CI: 1.66-3.83, P < 0.05). In addition, significant correlations between COX-2 overexpression and overall survival of laryngeal cancer were found both in Asians and in Caucasians (total, HR = 1.73, 95% CI: 1.23-2.24, P < 0.05; survival in Asians, HR = 2.59, 95% CI: 1.27-3.92, P < 0.05; survival in Caucasians, HR = 1.59, 95% CI: 1.03-2.14, P < 0.05). Conclusions: The meta-analysis results suggested that COX-2 overexpression was significantly associated with the increased risk, worse clinicopathological progression, and poorer prognosis of laryngeal cancer.

Longitudinal and proteome-wide analyses of antibodies in COVID-19 patients reveal features of the humoral immune response to SARS-CoV-2.

Introduction: The SARS-CoV-2 pandemic has endangered global health, the world economy, and societal values. Despite intensive measures taken around the world, morbidity and mortality remain high as many countries face new waves of infection and the spread of new variants. Worryingly, more and more variants are now being identified, such as 501Y.V1 (B.1.1.7) in the UK, 501Y.V2 (B.1.351) in South Africa, 501Y.V3 in Manaus, Brazil, and B.1.617/B.1.618 in India, which could lead to a severe epidemic rebound. Moreover, some variants have a stronger immune escape ability. To control the new SARS-CoV-2 variant, we may need to develop and redesign new vaccines repeatedly. So it is important to investigate how our immune system combats and responds to SARS-CoV-2 infection to develop safe and effective medical interventions. Objectives: In this study, we performed a longitudinal and proteome-wide analysis of antibodies in the COVID-19 patients to revealed some immune processes of COVID-19 patients against SARS-CoV-2 and found some dominant epitopes of a potential vaccine. Methods: Microarray assay, Antibody depletion assays, Neutralization assay. Results: We profiled a B-cell linear epitope landscape of SARS-CoV-2 and identified the epitopes specifically recognized by either IgM, IgG, or IgA. We found that epitopes more frequently recognized by IgM are enriched in non-structural proteins. We further identified epitopes with different immune responses in severe and mild patients. Moreover, we identified 12 dominant epitopes eliciting antibodies in most COVID-19 patients and identified five key amino acids of epitopes. Furthermore, we found epitope S-82 and S-15 are perfect immunogenic peptides and should be considered in vaccine design. Conclusion: This data provide useful information and rich resources for improving our understanding of viral infection and developing a novel vaccine/neutralizing antibodies for the treatment of SARS-CoV-2.

Longitudinal Metabolomics Reveals Ornithine Cycle Dysregulation Correlates With Inflammation and Coagulation in COVID-19 Severe Patients.

COVID-19 is a severe disease in humans, as highlighted by the current global pandemic. Several studies about the metabolome of COVID-19 patients have revealed metabolic disorders and some potential diagnostic markers during disease progression. However, the longitudinal changes of metabolomics in COVID-19 patients, especially their association with disease progression, are still unclear. Here, we systematically analyzed the dynamic changes of the serum metabolome of COVID-19 patients, demonstrating that most of the metabolites did not recover by 1-3 days before discharge. A prominent signature in COVID-19 patients comprised metabolites of amino acids, peptides, and analogs, involving nine essential amino acids, 10 dipeptides, and four N-acetylated amino acids. The levels of 12 metabolites in amino acid metabolism, especially three metabolites of the ornithine cycle, were significantly higher in severe patients than in mild ones, mainly on days 1-3 or 4-6 since onset. Integrating blood metabolomic, biochemical, and cytokine data, we uncovered a highly correlated network, including 6 cytokines, 13 biochemical parameters, and 49 metabolites. Significantly, five ornithine cycle-related metabolites (ornithine, N-acetylornithine, 3-amino-2-piperidone, aspartic acid, and asparagine) highly correlated with "cytokine storms" and coagulation index. We discovered that the ornithine cycle dysregulation significantly correlated with inflammation and coagulation in severe patients, which may be a potential mechanism of COVID-19 pathogenicity. Our study provided a valuable resource for detailed exploration of metabolic factors in COVID-19 patients, guiding metabolic recovery, understanding the pathogenic mechanisms, and creating drugs against SARS-CoV-2 infection.

B7 Family Molecule VSIG4 Regulates Intestinal Anti-Enterohemorrhagic Escherichia coli Immunity by Altering Gut Flora Diversity.

As an essential member of the B7 family, V-set and immunoglobulin domain-containing 4 (VSIG4) is expressed explicitly in tissue-resident macrophages (TRMs) and plays an essential role in maintaining the homeostasis of the environmental immune system. Here, we demonstrate that gene-targeted VSIG4-deficient mice infected with Enterohemorrhagic Escherichia coli (EHEC) display reduced bacterial burden. To reveal the role of VSIG4 in the fight against EHEC infection, we collected mice feces and used high-throughput 16S rRNA gene amplicons to detect changes in the flora. A total of 657330 sequences were sequenced on the PacBio platform, with an average length of 1498 bp. We found that VSIG4 deficiency could alter the gut microbiota by increasing diversity and shifting community composition. In particular, G_Akkermansia and G_Oscillo spiraceae increased significantly. These findings expand upon a prior observation that VSIG4 deficiency reduced EHEC colonization by changing the gut microbiota diversity and shifting community composition.

A Chimeric Cationic Peptide Composed of Human ß-Defensin 3 and Human ß-Defensin 4 Exhibits Improved Antibacterial Activity and Salt Resistance.

Human beta-defensins (hBDs) play an important role in the host defense against various microbes, showing different levels of antibacterial activity and salt resistance in vitro. It is of interest to investigate whether can chimeric hBD analogs enhanced antibacterial activity and salt resistance. In this study, we designed a chimeric human defensin, named H4, by combining sequences of human beta-defensin-3 (hBD-3) and human beta-defensin-4 (hBD-4), then evaluated its antibacterial activity, salt resistance, and cytotoxic effects. The result showed that the antibacterial activity of H4 against most tested strains, including Klebsiella pneumonia, Enterococcus faecalis, Staphyloccocus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Acinetobacter baumannii was significantly improved compared to that of hBD-3 and hBD-4. Notably, H4 exhibited significantly better antibacterial activity against multidrug resistant isolate A. baumannii MDR-ZJ06 than commonly used antibiotics. Chimeric H4 still showed more than 80% antibacterial activity at high salt concentration (150 µM), which proves its good salt tolerance. The cytotoxic effect assay showed that the toxicity of H4 to Hela, Vero, A549 cells and erythrocytes at a low dose (<10 µg/ml) was similar to that of hBD-3 and hBD-4. In conclusion, given its broad spectrum of antibacterial activity and high salt resistance, chimeric H4 could serve as a promising template for new therapeutic antimicrobial agents.

AtaT Improves the Stability of Pore-Forming Protein EspB by Acetylating Lysine 206 to Enhance Strain Virulence.

A novel type II toxin of toxin-antitoxin systems (TAs), Gcn5-related N-acetyltransferase (GNAT) family, was reported recently. GNAT toxins are mainly present in pathogenic species, but studies of their involvement in pathogenicity are rare. This study discovered that the GANT toxin AtaT in enterohemorrhagic Escherichia coli (EHEC) can significantly enhance strain pathogenicity. First, we detected the virulence of ΔataT and ΔataR in cell and animal models. In the absence of ataT, strains showed a lower adhesion number, and host cells presented weaker attaching and effacing lesions, inflammatory response, and pathological injury. Next, we screened the acetylation substrate of AtaT to understand the underlying mechanism. Results showed that E. coli pore-forming protein EspB, which acts as a translocon in type III secretion system (T3SS) in strains, can be acetylated specifically by AtaT. The acetylation of K206 in EspB increases protein stability and maintains the efficiency of effectors translocating into host cells to cause close adhesion and tissue damage.

Adaptation of SARS-CoV-2 in BALB/c mice for testing vaccine efficacy.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has prioritized the development of small-animal models for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We adapted a clinical isolate of SARS-CoV-2 by serial passaging in the respiratory tract of aged BALB/c mice. The resulting mouse-adapted strain at passage 6 (called MASCp6) showed increased infectivity in mouse lung and led to interstitial pneumonia and inflammatory responses in both young and aged mice after intranasal inoculation. Deep sequencing revealed a panel of adaptive mutations potentially associated with the increased virulence. In particular, the N501Y mutation is located at the receptor binding domain (RBD) of the spike protein. The protective efficacy of a recombinant RBD vaccine candidate was validated by using this model. Thus, this mouse-adapted strain and associated challenge model should be of value in evaluating vaccines and antivirals against SARS-CoV-2.

Protective Immunity Elicited by VP1 Chimeric Antigens of Bacterial Ghosts against Hand-Foot-and-Mouth Disease Virus.

This study was designed to evaluate the immunogenicity and protective efficacy of two VP1 chimeric antigens of bacterial ghosts. Inoculation of the two VP1 chimeric antigens of bacterial ghosts into BALB/c mice markedly elicited humoral and mucosal immune responses. The specific antibodies induced by the chimeric ghosts protected mice not only against the virus that causes hand-foot-and-mouth disease but also against E. coli O157:H7 bacterial infection. In comparison with the negative control, immunization with the chimeric ghosts protected mice against two LD50 hand-foot-and-mouth disease viral infection. In addition, this specific immunity also protected the pups of pregnant mice immunized with the VP1 chimeric antigens of bacterial ghosts against 20 MLD E. coli O157:H7 infection. Taken together, the results of this study verify for the first time that the VP1 chimeric antigens of bacterial ghosts are target candidates for a new type of vaccine against hand-foot-and-mouth disease. Additionally, this vaccine strategy also elicited a stronger immune response against E. coli O157:H7.

Serum soluble VSIG4 as a surrogate marker for the diagnosis of lymphoma-associated hemophagocytic lymphohistiocytosis.

Lymphoma-associated haemophagocytic lymphohistiocytosis (L-HLH) is characterized by excessively activated macrophages and cytotoxic T lymphocytes, but few reliable markers for activated macrophages are available clinically. This study, designed to discover novel biomarkers for the diagnosis of lymphoma patients with L-HLH, was initiated between 2016 and 2018. Fifty-seven adult lymphoma patients were enrolled - 39 without HLH and 18 with HLH. The differential serum protein expression profile was first screened between lymphoma patients with and without L-HLH by a quantitative mass spectrometric approach. Soluble V-set and immunoglobulin domain-containing 4 (sVSIG4), specifically expressed by macrophages, was significantly upregulated in the L-HLH group. Subsequently, sVSIG4 concentration was confirmed by enzyme-linked immunosorbent assay to be significantly increased in lymphoma patients with L-HLH. When it was exploited for the diagnosis of lymphoma patients with L-HLH, the area under a receiver operating characteristic curve was 0·98 with an optimal cut-off point of 2195 pg/ml and the corresponding sensitivity and specificity were 94·44% and 94·87% respectively. In addition, the one-year overall survival was significantly worse in patients with a sVSIG4 concentration above 2195 pg/ml compared with those below 2195 pg/ml (5·3% vs. 72·2%, P < 0·0001). sVSIG4 may be a surrogate marker of activated macrophages for the diagnosis of lymphoma patients with L-HLH.

Gentamicin Induced Microbiome Adaptations Associate With Increased BCAA Levels and Enhance Severity of Influenza Infection.

Involvement of gut microbiota in pulmonary disease by the gut-lung axis has been widely observed. However, the cross-talk messengers between respiratory mucosal immunity and gut microbiota are largely unknown. Using selective pharmacologic destruction of gut microenvironment mouse models, we found gut microbiota displayed significantly lower alpha diversity and relative abundance of bacteria in Gentamicin treated mice. Metagenomic studies revealed functional differences in gut bacteria in altering metabolic profiles in mice blood. Branched-chain amino acids (BCAAs) are the essential factors linked between gut and lung. During this process, selective destruction of gut microbiota by Gentamicin induced high levels of BCAAs, and the high levels of BCAAs impacted the lung immunity against influenza virus. In vivo, Gentamicin-treated mice or mice fed with high BCAAs diets displayed reduced survival. At the sites of infection, the number of CD11b+Ly6G+ cells decreased, and CD8+ T cells increased accompanied by exuberant expression of pro-inflammatory cytokines could result in tissue damage. CD11b+Ly6G+ cells transplantation conferred remarkable protection from influenza virus infections. In vitro, BCAAs promoted bone marrow-derived cells differentiation to dendritic cells. Taken together, these findings demonstrate that Gentamicin induced disruption of the gut microbiota leads to increased BCAA levels that suppress CD11b+Ly6c+ cell development in association with overactive CD8+ T responses which may contribute to enhanced severity of the viral infection.

VP1 of Enterovirus 71 Protects Mice Against Enterovirus 71 and Coxsackievirus B3 in Lethal Challenge Experiment.

Enterovirus and Coxsackievirus are the major viruses that cause hand, foot, and mouth disease (HFMD) outbreaks worldwide. Several studies have shown the potential of viral envelope protein 1 (VP1) on providing protective effects from viral strains of different genotypes. However, whether VP1 has the cross-protection in Enteroviruses or Coxsackievirus has not been studied in-depth. In this study, the vp1 gene of Enterovirus 71 (EV71) and Coxsackievirus B3 (CB3) was inserted into the vector pET22b (+) to form the respective expression plasmids pEVP1 or pCVP1, and then transformed into Escherichia coli strain BL21 (DE3). The recombinant EVP1 or CVP1 protein was overexpressed successfully and effectively purified to homogeneity. Then, we identified that EVP1 and CVP1 protein could generate effectively specific humoral immunity and cellular immunity in mice, what's more, we determined the cross-protection of VP1 between EV71 and CB3 in a murine model. The results showed that immunization with EVP1 could effectively induce specific IgG and secretory IgA against CVP1 and the sera from EVP1-immunized mice could neutralize CB3 with mean titers 1:440. In contrast, no measurable neutralizing antibodies to EV71 were detected in CVP1-immunized mice. Then, newborn BALB/C mice, whose mother was immunized with EVP1 or CVP1, were administered with different lethal doses of EV71 or CB3. The EVP1 immunized group showed a 90% protective efficacy for a CB3 dosage of 120 LD50, but the CVP1 immunized group showed no significantly different protective efficacy against 15 LD50 of EV71 compared with the BSA immunized group. Hence, EVP1 is a promising subunit vaccine candidate against Enterovirus 71 and Coxsackievirus B3 caused HFMD.

Immunogenicity and Protection from Receptor-Binding Domains of Toxins as Potential Vaccine Candidates for Clostridium difficile.

The receptor-binding domains (RBDs) located in toxin A and toxin B of Clostridium difficile are known to be nontoxic and immunogenic. We need to develop a new type vaccine based on RBDs. In this study, we expressed and purified recombinant proteins (named RBD-TcdA and RBD-TcdB) as vaccine candidates containing the RBDs of toxin A and toxin B, respectively, from the C. difficile reference strain VPI10463. The immunogenicity and protection of the vaccine candidates RBD-TcdA, RBD-TcdB, and RBD-TcdA/B was evaluated by ELISA and survival assays. The data indicated that mice immunized with all vaccine candidates displayed potent levels of RBD-specific serum IgG. Following intramuscular immunization of mice with RBD-TcdA and/or RBD-TcdB, these vaccine candidates triggered immune responses that protected mice compared to mice immunized with aluminum hydroxide alone. Taken together, the results of this study reveal that recombinant proteins containing RBDs of C. difficile toxins can be used for vaccine development. Additionally, we found that an RBD-TcdA/B vaccine can elicit a stronger humoral immune response and provide better immunoprotection than the univalent vaccines. This RBD vaccine candidate conferred significant protection against disease symptoms and death caused by toxins from a wild-type C. difficile strain.

Essential roles for platelets during neutrophil-dependent or lymphocyte-mediated defense against bacterial pathogens.

Emerging evidence from animal models suggests that platelets may participate in a wide variety of processes including the immune response against infection. More than 200 whole blood samples from patients and healthy controls were run in the System XE-5000 analyzer, and plasma fractions were separated for the following tests by ELISA, Luminex and light scattering. We describe two mechanisms by which platelets may contribute to immune function against various bacterial pathogens based on increased mean platelet volume in gram-positive bacterial infections and increased platelet counts in gram-negative bacterial infections. Gram-negative bacteria activate platelets to recruit neutrophils, which participate in the immune response against infection. During this process, fractalkine, macrophage inflammatory protein-1ß, interleukin-17A, tumor necrosis factor-α and platelet-activating factor were higher in patients infected with Escherichia coli; additionally, giant platelets were observed under the microscope. Meanwhile, we found that platelets played a different role in gram-positive bacterial infections. Specifically, they could actively adhere to gram-positive bacteria in circulation and transfer them to immune sites to promote antibacterial lymphocyte expansion. During this process, complement C3 and factor XI were more highly expressed in patients infected with Staphylococcus aureus; additionally, we detected more small platelets under the microscope. Platelets participate in the immune response against both gram-negative and gram-positive bacteria, although the mechanisms differ. These results will help us understand the complex roles of platelets during infections, and direct our use of antibiotics based on clinical platelet data.