HIV BG505 SOSIP.664 trimer with 3M-052-AF/alum induces human autologous tier-2 neutralizing antibodies.

Stabilized trimers preserving the native-like HIV envelope structure may be key components of a preventive HIV vaccine regimen to induce broadly neutralizing antibodies (bnAbs). We evaluated trimeric BG505 SOSIP.664 gp140, formulated with a novel TLR7/8 signaling adjuvant, 3M-052-AF/Alum, for safety, adjuvant dose-finding and immunogenicity in a first-in-healthy adult (n=17), randomized, placebo-controlled trial (HVTN 137A). The vaccine regimen appeared safe. Robust, trimer-specific antibody, B-cell and CD4+ T-cell responses emerged post-vaccination. Five vaccinees developed serum autologous tier-2 nAbs (ID50 titer, 1:28-1:8647) after 2-3 doses targeting C3/V5 and/or V1/V2/V3 Env regions by electron microscopy and mutated pseudovirus-based neutralization analyses. Trimer-specific, B-cell-derived monoclonal antibody activities confirmed these results and showed weak heterologous neutralization in the strongest responder. Our findings demonstrate the clinical utility of the 3M-052-AF/alum adjuvant and support further improvements of trimer-based Env immunogens to focus responses on multiple broad nAb epitopes. KEY TAKEAWAY/TAKE-HOME MESSAGES: HIV BG505 SOSIP.664 trimer with novel 3M-052-AF/alum adjuvant in humans appears safe and induces serum neutralizing antibodies to matched clade A, tier 2 virus, that map to diverse Env epitopes with relatively high titers. The novel adjuvant may be an important mediator of vaccine response.

Targeting enhanced neutralizing antibody responses via increased germinal center activity: early-phase vaccine trials with novel clinical designs.

PURPOSE OF REVIEW: Recent advances in the understanding of the difficult immunologic requirements for the induction of broadly neutralizing antibodies for HIV have spurred interest in optimizing vaccine approaches intended to stimulate a robust germinal center reaction. In preclinical models, techniques to optimize the germinal center response have included alterations in the timing, dose, and delivery method of immunogens and have resulted in substantially enhanced germinal center responses in lymph nodes and neutralizing antibodies in serum. One of the most promising approaches involves splitting the initial dose of vaccine into a series of gradual escalating doses administration ("fractional escalating doses"). In principle, these techniques may have broad implications for vaccines targeting a robust antibody response. RECENT FINDINGS: We review the upcoming vaccine trials that will test these concepts in clinical practice. The trials include both HIV and non-HIV immunogens, and will involve testing these concepts in both healthy adults and immunocompromised persons. SUMMARY: There are multiple trials that will test whether techniques to alter vaccine delivery such as fractional escalating doses enhances immunologic outcomes.

COVID-19 Vaccines.

This article is a narrative review of the rapidly moving coronavirus disease 2019 vaccine field with an emphasis on clinical efficacy established in both randomized trials and postmarketing surveillance of clinically available vaccines. We review the major clinical trials that supported authorization for general use of the Janssen (Ad.26.CoV2), Pfizer-BioNTech (BNT162b2), and Moderna (mRNA-1273) vaccines and the publicly available postmarketing information with the goal of providing a broad, clinically relevant comparison of efficacy and safety. This review is primarily focused on the US market.

B cell intrinsic expression of IFNλ receptor suppresses the acute humoral immune response to experimental blood-stage malaria.

Antibodies play a critical protective role in the host response to blood-stage malaria infection. The role of cytokines in shaping the antibody response to blood-stage malaria is unclear. Interferon lambda (IFNλ), a type III interferon, is a cytokine produced early during blood-stage malaria infection that has an unknown physiological role during malaria infection. We demonstrate that B cell-intrinsic IFNλ signals suppress the acute antibody response, acute plasmablast response, and impede acute parasite clearance during a primary blood-stage malaria infection. Our findings demonstrate a previously unappreciated role for B cell intrinsic IFNλ-signaling in the initiation of the humoral immune response in the host response to experimental malaria.

A Prediction Model for Severe AKI in Critically Ill Adults That Incorporates Clinical and Biomarker Data.

BACKGROUND AND OBJECTIVES: Critically ill patients with worsening AKI are at high risk for poor outcomes. Predicting which patients will experience progression of AKI remains elusive. We sought to develop and validate a risk model for predicting severe AKI within 72 hours after intensive care unit admission. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We applied least absolute shrinkage and selection operator regression methodology to two prospectively enrolled, critically ill cohorts of patients who met criteria for the systemic inflammatory response syndrome, enrolled within 24-48 hours after hospital admission. The risk models were derived and internally validated in 1075 patients and externally validated in 262 patients. Demographics and laboratory and plasma biomarkers of inflammation or endothelial dysfunction were used in the prediction models. Severe AKI was defined as Kidney Disease Improving Global Outcomes (KDIGO) stage 2 or 3. RESULTS: Severe AKI developed in 62 (8%) patients in the derivation, 26 (8%) patients in the internal validation, and 15 (6%) patients in the external validation cohorts. In the derivation cohort, a three-variable model (age, cirrhosis, and soluble TNF receptor-1 concentrations [ACT]) had a c-statistic of 0.95 (95% confidence interval [95% CI], 0.91 to 0.97). The ACT model performed well in the internal (c-statistic, 0.90; 95% CI, 0.82 to 0.96) and external (c-statistic, 0.93; 95% CI, 0.89 to 0.97) validation cohorts. The ACT model had moderate positive predictive values (0.50-0.95) and high negative predictive values (0.94-0.95) for severe AKI in all three cohorts. CONCLUSIONS: ACT is a simple, robust model that could be applied to improve risk prognostication and better target clinical trial enrollment in critically ill patients with AKI.

Chronic TLR7 and TLR9 signaling drives anemia via differentiation of specialized hemophagocytes.

Cytopenias are an important clinical problem associated with inflammatory disease and infection. We show that specialized phagocytes that internalize red blood cells develop in Toll-like receptor 7 (TLR7)-driven inflammation. TLR7 signaling caused the development of inflammatory hemophagocytes (iHPCs), which resemble splenic red pulp macrophages but are a distinct population derived from Ly6Chi monocytes. iHPCs were responsible for anemia and thrombocytopenia in TLR7-overexpressing mice, which have a macrophage activation syndrome (MAS)-like disease. Interferon regulatory factor 5 (IRF5), associated with MAS, participated in TLR7-driven iHPC differentiation. We also found iHPCs during experimental malarial anemia, in which they required endosomal TLR and MyD88 signaling for differentiation. Our findings uncover a mechanism by which TLR7 and TLR9 specify monocyte fate and identify a specialized population of phagocytes responsible for anemia and thrombocytopenia associated with inflammation and infection.

Identification of Acute Kidney Injury Subphenotypes with Differing Molecular Signatures and Responses to Vasopressin Therapy.

RATIONALE: Currently, no safe and effective pharmacologic interventions exist for acute kidney injury (AKI). One reason may be that heterogeneity exists within the AKI population, thereby hampering the identification of specific pathophysiologic pathways and therapeutic targets. OBJECTIVE: The aim of this study was to identify and test whether AKI subphenotypes have prognostic and therapeutic implications. METHODS: First, latent class analysis methodology was applied independently in two critically ill populations (discovery [n = 794] and replication [n = 425]) with AKI. Second, a parsimonious classification model was developed to identify AKI subphenotypes. Third, the classification model was applied to patients with AKI in VASST (Vasopressin and Septic Shock Trial; n = 271), and differences in treatment response were determined. In all three populations, AKI was defined using serum creatinine and urine output. MEASUREMENTS AND MAIN RESULTS: A two-subphenotype latent class analysis model had the best fit in both the discovery (P = 0.004) and replication (P = 0.004) AKI groups. The risk of 7-day renal nonrecovery and 28-day mortality was greater with AKI subphenotype 2 (AKI-SP2) relative to AKI subphenotype 1 (AKI-SP1). The AKI subphenotypes discriminated risk for poor clinical outcomes better than the Kidney Disease: Improving Global Outcomes stages of AKI. A three-variable model that included markers of endothelial dysfunction and inflammation accurately determined subphenotype membership (C-statistic 0.92). In VASST, vasopressin compared with norepinephrine was associated with improved 90-day mortality in AKI-SP1 (27% vs. 46%, respectively; P = 0.02), but no significant difference was observed in AKI-SP2 (45% vs. 49%, respectively; P = 0.99) and the P value for interaction was 0.05. CONCLUSIONS: This analysis identified two molecularly distinct AKI subphenotypes with different clinical outcomes and responses to vasopressin therapy. Identification of AKI subphenotypes could improve risk prognostication and may be useful for predictive enrichment in clinical trials.

cGAS-mediated control of blood-stage malaria promotes Plasmodium-specific germinal center responses.

Sensing of pathogens by host pattern recognition receptors is essential for activating the immune response during infection. We used a nonlethal murine model of malaria (Plasmodium yoelii 17XNL) to assess the contribution of the pattern recognition receptor cyclic GMP-AMP synthase (cGAS) to the development of humoral immunity. Despite previous reports suggesting a critical, intrinsic role for cGAS in early B cell responses, cGAS-deficient (cGAS-/-) mice had no defect in the early expansion or differentiation of Plasmodium-specific B cells. As the infection proceeded, however, cGAS-/- mice exhibited higher parasite burdens and aberrant germinal center and memory B cell formation when compared with littermate controls. Antimalarial drugs were used to further demonstrate that the disrupted humoral response was not B cell intrinsic but instead was a secondary effect of a loss of parasite control. These findings therefore demonstrate that cGAS-mediated innate-sensing contributes to parasite control but is not intrinsically required for the development of humoral immunity. Our findings highlight the need to consider the indirect effects of pathogen burden in investigations examining how the innate immune system affects the adaptive immune response.

A Two-Biomarker Model Predicts Mortality in the Critically Ill with Sepsis.

RATIONALE: Improving the prospective identification of patients with systemic inflammatory response syndrome (SIRS) and sepsis at low risk for organ dysfunction and death is a major clinical challenge. OBJECTIVES: To develop and validate a multibiomarker-based prediction model for 28-day mortality in critically ill patients with SIRS and sepsis. METHODS: A derivation cohort (n = 888) and internal test cohort (n = 278) were taken from a prospective study of critically ill intensive care unit (ICU) patients meeting two of four SIRS criteria at an academic medical center for whom plasma was obtained within 24 hours. The validation cohort (n = 759) was taken from a prospective cohort enrolled at another academic medical center ICU for whom plasma was obtained within 48 hours. We measured concentrations of angiopoietin-1, angiopoietin-2, IL-6, IL-8, soluble tumor necrosis factor receptor-1, soluble vascular cell adhesion molecule-1, granulocyte colony-stimulating factor, and soluble Fas. MEASUREMENTS AND MAIN RESULTS: We identified a two-biomarker model in the derivation cohort that predicted mortality (area under the receiver operator characteristic curve [AUC], 0.79; 95% confidence interval [CI], 0.74-0.83). It performed well in the internal test cohort (AUC, 0.75; 95% CI, 0.65-0.85) and the external validation cohort (AUC, 0.77; 95% CI, 0.72-0.83). We determined a model score threshold demonstrating high negative predictive value (0.95) for death. In addition to a low risk of death, patients below this threshold had shorter ICU length of stay, lower incidence of acute kidney injury, acute respiratory distress syndrome, and need for vasopressors. CONCLUSIONS: We have developed a simple, robust biomarker-based model that identifies patients with SIRS/sepsis at low risk for death and organ dysfunction.

Blood Stage Malaria Disrupts Humoral Immunity to the Pre-erythrocytic Stage Circumsporozoite Protein.

Many current malaria vaccines target the pre-erythrocytic stage of infection in the liver. However, in malaria-endemic regions, increased blood stage exposure is associated with decreased vaccine efficacy, thereby challenging current vaccine efforts. We hypothesized that pre-erythrocytic humoral immunity is directly disrupted by blood stage infection. To investigate this possibility, we used Plasmodium-antigen tetramers to analyze B cells after infection with either late liver stage arresting parasites or wild-type parasites that progress to the blood stage. Our data demonstrate that immunoglobulin G (IgG) antibodies against the pre-erythrocytic antigen, circumsporozoite protein (CSP), are generated only in response to the attenuated, but not the wild-type, infection. Further analyses revealed that blood stage malaria inhibits CSP-specific germinal center B cell differentiation and modulates chemokine expression. This results in aberrant memory formation and the loss of a rapid secondary B cell response. These data highlight how immunization with attenuated parasites may drive optimal immunity to malaria.

Malaria in the Traveler: How to Manage Before Departure and Evaluate Upon Return.

Malaria is the clinical syndrome when a patient experiences symptoms in response to infection with one of several strains of the Plasmodium parasite. This article is intended for health care providers to become familiar with some of the basics of care of patients who are travelling to or returning from an area with ongoing malaria transmission. The specific focus is on patients from nonendemic areas who plan on travel for a finite period to an area where malaria is endemic.

A common TLR1 polymorphism is associated with higher parasitaemia in a Southeast Asian population with Plasmodium falciparum malaria.

BACKGROUND: The factors leading to poor outcomes in malaria infection are incompletely understood. Common genetic variation exists in the human genes for Toll like receptors (TLRs) that alter host responses to pathogen-associated molecular patterns. Genetic variation in TLR1 and TLR6 could alter the risk of development of complicated malaria and ability of the host to control the parasite burden during acute Plasmodium falciparum infection. METHODS: Five single nucleotide polymorphisms in TLR1 and TLR6 in 432 patients with clinical P. falciparum monoinfection acquired on the Thai-Myanmar border were genotyped. Using logistic regression, associations with the development of complicated malaria and the percentage of infected erythrocytes (parasitaemia) on the day of presentation to clinical care (day zero) were tested. RESULTS: Genotypes carrying the T (major) allele of TLR1 rs5743551--an allele associated with improved outcomes in sepsis--were associated with higher parasitaemia measured on day zero (p = 0.03). DISCUSSION: Since malaria exerts strong genetic pressure on the human genome, protection from parasitaemia associated with TLR1 rs5743551 may account for the maintenance of an allele associated with poor outcomes in Caucasians with sepsis. CONCLUSION: These data suggest that genetic variation in TLR1 has effects on the host response to Plasmodium falciparum malaria in Asian populations. Genotypes from TLR6 showed no evidence of association with either complicated malaria or parasite burden.

Emergence of High-Level Daptomycin Resistance in Corynebacterium striatum in Two Patients with Left Ventricular Assist Device Infections.

INTRODUCTION: We describe the clinical and microbiologic courses of two patients with ventricular assist device infections secondary to Corynebacterium striatum treated with daptomycin. In both cases, the pathogen was initially susceptible to daptomycin (minimum inhibitory concentration [MIC] <0.125 mg/L) but became resistant (MIC >256 mg/L) during therapy. METHODS: The clonal nature of the isolates was determined by pulse-field gel electrophoresis (PFGE). Daptomycin binding was assessed by fluorescence microscopy using daptomycin-boron-dipyrromethene (bodipy). Induction and stability of daptomycin resistance were assessed by culturing strains in the presence of low concentrations of daptomycin or passage of resistant strains on daptomycin-free medium and repeat MIC testing, respectively. RESULTS: PFGE revealed that resistant clinical isolates were genetically indistinguishable from their parent strains, but the two pairs were unrelated to each other. The resistant strains had 7.5-15 times lower binding of daptomycin-bodipy compared to the related susceptible strains (p ≤ 0.0002). High-level daptomycin resistance (MIC >256 mg/L) was generated in vitro for both susceptible parent strains after overnight culture in the presence of daptomycin. One of the resistant strains maintained a high-level resistance phenotype up to 5 days of passage on daptomycin-free medium, whereas the other strain reverted back to a susceptible phenotype (MIC = 0.38 mg/L) after one passage on daptomycin-free medium, with a concomitant increase in daptomycin binding. CONCLUSIONS: High-level daptomycin resistance in C. striatum was readily generated in vitro and during the course of therapy in these patients. This resistance appears to be mediated by reduced daptomycin binding. Providers should be cautious about using long-term daptomycin monotherapy for C. striatum infections.

Biomarkers of Endothelial Activation Are Associated with Poor Outcome in Critical Illness.

BACKGROUND: Endothelial activation plays a role in organ dysfunction in the systemic inflammatory response syndrome (SIRS). Angiopoietin-1 (Ang-1) promotes vascular quiescence while angiopoietin-2 (Ang-2) mediates microvascular leak. Circulating levels of Ang-1 and Ang-2 in patients with SIRS could provide insight on risks for organ dysfunction and death distinct from inflammatory proteins. In this study, we determined if biomarkers of endothelial activation and inflammation exhibit independent associations with poor outcomes in SIRS. METHODS: We studied 943 critically ill patients with SIRS admitted to an Intensive Care Unit (ICU) of an academic medical center. We measured plasma levels of endothelial markers (Ang-1, Ang-2, soluble vascular cell adhesion molecule-1 (sVCAM-1)) and inflammatory markers (interleukin-6 (IL-6), interleukin-8 (IL-8), granulocyte-colony stimulating factor (G-CSF), soluble tumor necrosis factor receptor-1 (sTNFR-1)) within 24 hours of enrollment. We tested for associations between each marker and 28 day mortality, shock, and day 3 sequential organ failure assessment (SOFA) score. For 28 day mortality, we performed sensitivity analysis for those subjects with sepsis and those with sterile inflammation. We used multivariate models to adjust for clinical covariates and determine if associations identified with endothelial activation markers were independent of those observed with inflammatory markers. RESULTS: Higher levels of all biomarkers were associated with increased 28 day mortality except levels of Ang-1 which were associated with lower mortality. After adjustment for comorbidities and sTNFR-1 concentration, a doubling of Ang-1 concentration was associated with lower 28 day mortality (Odds ratio (OR) = 0.81; p<0.01), shock (OR = 0.82; p<0.001), and SOFA score (ß = -0.50; p<0.001), while Ang-2 concentration was associated with increased mortality (OR = 1.55; p<0.001), shock (OR = 1.51; p<0.001), and SOFA score (ß = +0.63; p<0.001). sVCAM-1 was not independently associated with SIRS outcomes. CONCLUSIONS: In critically ill patients with SIRS, early measurements of Ang-1 and Ang-2 are associated with death and organ dysfunction independently of simultaneously-measured markers of inflammation.