It is currently not possible to predict which epitopes will be recognized by T cells in different individuals. This is a barrier to the thorough analysis and understanding of T-cell responses after vaccination or infection. Here, by combining mass cytometry with combinatorial peptide–MHC tetramer staining, we have developed a method allowing the rapid and simultaneous identification and characterization of T cells specific for many epitopes. We use this to screen up to 109 different peptide–MHC tetramers in a single human blood sample, while still retaining at least 23 labels to analyze other markers of T-cell phenotype and function. Among 77 candidate rotavirus epitopes, we identified six T-cell epitopes restricted to human leukocyte antigen (HLA)-A*0201 in the blood of healthy individuals. T cells specific for epitopes in the rotavirus VP3 protein displayed a distinct phenotype and were present at high frequencies in intestinal epithelium. This approach should be useful for the comprehensive analysis of T-cell responses to infectious diseases or vaccines.

"Bulk" measurements of antiviral innate immune responses from pooled cells yield averaged signals and do not reveal underlying signaling heterogeneity in infected and bystander single cells. We examined such heterogeneity in the small intestine during rotavirus (RV) infection. Murine RV EW robustly activated type I IFNs and several antiviral genes (IFN-stimulated genes) in the intestine by bulk analysis, the source of induced IFNs primarily being hematopoietic cells. −/− mice revealed that murine but not simian RRV mediated accumulation of IkB-α protein and decreased transcription of NF-κB-dependent genes. RRV replication was significantly rescued in IFN types I and II, as well as STAT1 (IFN types I, II, and III) deficient mice in contrast to EW, which was only modestly sensitive to IFNs I and II. Resolution of "averaged" innate immune responses in single IECs thus revealed unexpected heterogeneity in both the induction and subversion of early host antiviral immunity, which modulated host range.innate immunity | interferon and antiviral response | single-cell analysis | NF-κB signaling | IRF3 signaling F ollowing virus infection, eukaryotic cells respond by the activation of innate immunity in a cell type-and strain-specific manner. The early host innate response includes activation of the transcription factors IRF3 and NF-κB, which induce transcription of discrete and overlapping sets of genes, including those encoding type I IFNs and viral stress-induced genes (vSIGs) (1, 2). Following IFN secretion and binding to cognate receptors, there is feed-forward amplification of expression of IFN and several hundred IFN-stimulated genes (ISGs), resulting in the establishment of an antiviral state. Such early responses to the presence of viral particles are spatially distinct from those that occur in adjacent bystander cells lacking direct exposure to virus. The early host innate immune responses to virus generally have been measured using averaged signals from "bulk" populations of cells or whole tissues. Such analyses cannot reveal hierarchical responses in individual infected or bystander cells. Here, we used a single-cell analytic strategy to examine the diversity in the early host antiviral innate immune response to rotavirus (RV) in suckling mice.RVs cause severe dehydrating diarrhea in the young of many mammalian species, resulting in more than 400,000 deaths of children annually (3). Homologous RV (RV derived from the infected host species) replicates efficiently within mature absorptive villous enterocytes of the small intestine but in the immune competent host, does not replicate efficiently in crypts or colon or at extraintestinal systemic locations (4). RV has evolved mechanisms to effectively block IRF3 and NF-κB-dependent IFN induction, as well as feedback-dependent amplification stages of the innate antiviral response (5). Specifically, the RV nonstructural protein NSP1 mediates degradation of IRF3 and/or NF-κB regulatory factor β-TrCP, depending on the viral strain and host cell involved (6, 7). In addi...

Purpose: This phase I study assessed the safety, pharmacokinetics (PKs), and efficacy of MIW815 (ADU-S100), a novel synthetic cyclic dinucleotide that activates the stimulator of IFN genes (STING) pathway, in patients with advanced/metastatic cancers. Patients and Methods: Patients (n = 47) received weekly i.t. injections of MIW815, 50 to 6,400 μg, on a 3-weeks-on/1-week-off schedule. Results: A maximum tolerated dose was not reached. Most common treatment-related adverse events were pyrexia (17%), chills, and injection-site pain (each 15%). MIW815 was rapidly absorbed from the injection site with dose-proportional PK, a rapid terminal plasma half-life (approximately 24 minutes), and high interindividual variability. One patient had a partial response (PR; Merkel cell carcinoma); two patients had unconfirmed PR (parotid cancer, myxofibrosarcoma). Lesion size was stable or decreased in 94% of evaluable, injected lesions. RNA expression and immune infiltration assessments in paired tumor biopsies did not reveal significant on-treatment changes. However, increases in inflammatory cytokines and peripheral blood T-cell clonal expansion suggested systemic immune activation. Conclusions: MIW815 was well tolerated in patients with advanced/metastatic cancers. Clinical activity of single-agent MIW815 was limited in this first-in-human study; however, evidence of systemic immune activation was seen.

Human rotaviruses (RVs) are the leading cause of severe diarrhea in young children worldwide. The molecular mechanisms underlying the rapid induction of heterotypic protective immunity to RV, which provides the basis for the efficacy of licensed monovalent RV vaccines, have remained unknown for more than 30 years. We used RV-specific single cell-sorted intestinal B cells from human adults, barcode-based deep sequencing of antibody repertoires, monoclonal antibody expression, and serologic and functional characterization to demonstrate that infection-induced heterotypic immunoglobulins (Igs) primarily directed to VP5*, the stalk region of the RV attachment protein, VP4, are able to mediate heterotypic protective immunity. Heterotypic protective Igs against VP7, the capsid glycoprotein, and VP8*, the cell-binding region of VP4, are also generated after infection; however, our data suggest that homotypic anti-VP7 and non-neutralizing VP8* responses occur more commonly in people. These results indicate that humans can circumvent the extensive serotypic diversity of circulating RV strains by generating frequent heterotypic neutralizing antibody responses to VP7, VP8*, and most often, to VP5* after natural infection. These findings further suggest that recombinant VP5* may represent a useful target for the development of an improved, third-generation, broadly effective RV vaccine and warrants more direct examination.

Purpose: Limited options exist for patients with advanced pancreatic cancer progressing after 1 or more lines of therapy. A phase II study in patients with previously treated metastatic pancreatic cancer showed that combining GVAX pancreas (granulocyte-macrophage colony-stimulating factor-secreting allogeneic pancreatic tumor cells) with cyclophosphamide (Cy) and CRS-207 (live, attenuated Listeria monocytogenes expressing mesothelin) resulted in median overall survival (OS) of 6.1 months, which compares favorably with historical OS achieved with chemotherapy. In the current study, we compared Cy/GVAX þ CRS-207, CRS-207 alone, and standard chemotherapy in a three-arm, randomized, controlled phase IIb trial. Patients and Methods: Patients with previously treated metastatic pancreatic adenocarcinoma were randomized 1:1:1 to receive Cy/GVAX þ CRS-207 (arm A), CRS-207 (arm B), or physician's choice of single-agent chemotherapy (arm C). The primary cohort included patients who had failed !2 prior lines of therapy, including gemcitabine. The primary objective compared OS between arms A and C in the primary cohort. The second-line cohort included patients who had received 1 prior line of therapy. Additional objectives included OS between all treatment arms, safety, and tumor responses. Results: The study did not meet its primary efficacy endpoint. At the final study analysis, median OS [95% confidence interval (CI)] in the primary cohort (N ¼ 213) was 3.7 (2.9-5.3), 5.4 (4.2-6.4), and 4.6 (4.2-5.7) months in arms A, B, and C, respectively, showing no significant difference between arm A and arm C [P ¼ not significant (NS), HR ¼ 1.17; 95% CI, 0.84-1.64]. The most frequently reported adverse events in all treatment groups were chills, pyrexia, fatigue, and nausea. No treatment-related deaths occurred. Conclusions: The combination of Cy/GVAX þ CRS-207 did not improve survival over chemotherapy. (ClinicalTrials.gov ID: NCT02004262) See related commentary by Salas-Benito et al., p. 5435