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Background Genetically engineered porcine donors are a potential solution for the shortage of human organs for transplantation. Incompatibilities between humans and porcine donors are largely due to carbohydrate xenoantigens on the surface of porcine cells, provoking an immune response which leads to xenograft rejection. Materials and Methods Multiplex genetic knockout of GGTA1, β4GalNT2, and CMAH is predicted to increase the rate of xenograft survival, as described previously for GGTA1. In this study, the clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats–associated protein 9 system was used to target genes relevant to xenotransplantation, and a method for highly efficient editing of multiple genes in primary porcine fibroblasts was described. Results Editing efficiencies greater than 85% were achieved for knockout of GGTA1, β4GalNT2, and CMAH. Conclusion The high-efficiency protocol presented here reduces scale and cost while accelerating the production of genetically engineered primary porcine fibroblast cells for in vitro studies and the production of animal models.

Mitral valve replacement in patients with severe mitral annular calcification is a high-risk operation with historically poor outcomes. Percutaneous trans-catheter heart valve (THV) implantation is an alternative therapy to the traditional open surgical approach, but carries significant risks including severe paravalvular leak, left ventricular outflow obstruction, and embolization. To address this, alternative treatment modalities have emerged from the growing experience with THV. Here, we describe an open trans-atrial implantation of a balloon expandable THV. Relative to percutaneous therapies, an open approach permits implanting and expanding the valve under direct visual guidance, with anchoring sutures to precisely position the valve. In comparison to traditional surgical approaches, the risk of left circumflex arterial injury and atrioventricular dissociation is reduced as the annular calcification is left alone and no suture lines are run along the annulus. We illustrate this technique using an Edwards Sapien 3 bioprosthetic valve with an Edwards certitude transthoracic delivery system.

Approximately 5% of patients undergoing transcatheter aortic valve replacement (TAVR) are not candidates for transfemoral (TF) access and existing alternative access strategies are imperfect. Suprasternal access is an alternative access technique where the innominate artery is cannulated from a small incision above the sternal notch. This technique provides excellent visualization of the innominate artery and the transcatheter valve can be aligned coaxially with the native aortic valve with minimal catheter angulation. Clinical outcomes with suprasternal TAVR have proven comparable to traditional TF TAVR, yet there are no head-to-head studies comparing different alternative access platforms against suprasternal access. Herein, we provide a visual review of the surgical technique and procedural steps, followed by a brief discussion of pre-procedural planning and the existing clinical data regarding this alternative access strategy.

Crucial transitions in cancer-including tumor initiation, local expansion, metastasis, and therapeutic resistance-involve complex interactions between cells within the dynamic tumor ecosystem. Transformative single-cell genomics technologies and spatial multiplex in situ methods now provide an opportunity to interrogate this complexity at unprecedented resolution. The Human Tumor Atlas Network (HTAN), part of the National Cancer Institute (NCI) Cancer Moonshot Initiative, will establish a clinical, experimental, computational, and organizational framework to generate informative and accessible three-dimensional atlases of cancer transitions for a diverse set of tumor types. This effort complements both ongoing efforts to map healthy organs and previous large-scale cancer genomics approaches focused on bulk sequencing at a single point in time. Generating single-cell, multiparametric, longitudinal atlases and integrating them with clinical outcomes should help identify novel predictive biomarkers and features as well as therapeutically relevant cell types, cell states, and cellular interactions across transitions. The resulting tumor atlases should have a profound impact on our understanding of cancer biology and have the potential to improve cancer detection, prevention, and therapeutic discovery for better precision-medicine treatments of cancer patients and those at risk for cancer.

BACKGROUND “Langerhans cell histiocytosis” (LCH) is a term that encompasses single-system or multisystem disorders traditionally characterized by a proliferation of clonal CD1a+/CD207+ myeloid-derived histiocytes. In most cases of LCH, mitogen-activated protein kinase (MAPK) pathway somatic mutations lead to near universal upregulation of phosphorylated extracellular signal-regulated kinase expression. The clinical manifestations of LCH are numerous, but bone involvement is common. Intracranial lesions, especially as isolated manifestations, are rare. OBSERVATIONS The authors presented the case of a long-term survivor of exclusive intracranial LCH that manifested with isolated craniofacial bone and intraparenchymal central nervous system recurrences, which were managed with 3 decades of multimodal therapy. The patient was initially diagnosed with LCH at age 2 years, and the authors documented the manifestations of disease and treatment for 36 years. Most of the patient’s treatment course occurred before the discovery of BRAF V600E. Treatments initially consisted of chemotherapy, radiosurgery, and open resections for granulomatous LCH lesions. Into young adulthood, the patient had a minimal disease burden but still required additional radiosurgical procedures and open resections. LESSONS Surgical treatments alleviated the patient’s immediate symptoms and allowed for tumor burden control. However, surgical interventions did not cure the underlying, aggressive disease. In the current era, access to systemic MAPK inhibitor therapy for histiocytic lesions may offer improved outcomes.

A trio of 1,4-diaryl-1,3-butadiynes with methoxy and trifluoromethoxy substituents in the 4- and 4′-positions were prepared in useful yields (42% for one, 95+% for the others), their structures determined and their purity ascertained. Analysis of the single crystal X-ray data for the three compounds revealed that two were mostly planar with small dihedral angles of 6–9° between their aryl rings, while one existed in a twisted conformation with a dihedral angle of approximately 53° between it's aryl rings. The solid-state absorption spectra of all three compounds were similar, with structured absorptions at approximately 340 nm. One of the compounds had absorption bands at 263 and 457 nm. Two of the compounds had similar emission bands with maxima that ranged from 440 to 450 nm, while the other was quite different, with a broad emission band with a maximum at 564 nm. Each of the three compounds had excited state decay traces that were fit to tri-exponential curves which yielded three lifetimes: a longer one attributed to aggregate emission, a shorter one arising from an intermolecular charge transfer transition, and a medium one that is assigned to a locally excited transition.

Most of the voice conversion systems available have only focused on the spectral parameter of the speech such as the spectral envelope. This project developed a voice conversion system that converts not only the spectral parameters but also the prosodic features of speech, specifically the Wavelet modeling of the F0 contour, to improve the voice quality and naturalness. This system can be used in conjunction with text-to-speech systems to introduce personalization and customization to the speech output. The project was implemented not only in the English language but also in the context of Philippine Spoken Languages such as Tagalog, Hiligaynon and Cebuano. Results show that the English voice conversion yielded the highest score in terms of naturalness with 2.7167 Mean-Opinion Score and Cebuano in terms of intelligibility with 3.0875 Mean-Opinion Score. Using the objective metrics, results show that Hiligaynon has the lowest Mel-Cepstral Distortion with 5.5335 while English yielded the lowest F0:RMSE with 20.254. Results also showed that intra-gender voice conversion performs better than inter-gender.

Yellow fever virus (YFV) is a mosquito-borne member of the genus flavivirus, including other important human-pathogenic viruses, such as dengue, Japanese encephalitis, and Zika. Herein, we report identifying 129 YFV Class II epitopes in donors vaccinated with the live attenuated YFV vaccine (YFV-17D). A total of 1156 peptides predicted to bind 17 different common HLA-DRB1 allelic variants were tested using IFN&gamma, ELISPOT assays in vitro re-stimulated peripheral blood mononuclear cells from twenty-six vaccinees. Overall, we detected responses against 215 YFV epitopes. We found that the capsid and envelope proteins, as well as the non-structural (NS) proteins NS3 and NS5, were the most targeted proteins by CD4+ T cells from YF-VAX vaccinated donors. In addition, we designed and validated by flow cytometry a CD4+ mega pool (MP) composed of structural and non-structural epitopes in an independent cohort of vaccinated donors. Overall, this study provides a comprehensive prediction and validation of YFV epitopes in a cohort of YF-17D vaccinated individuals. With the design of a CD4 epitope MP, we further provide a useful tool to detect ex vivo responses of YFV-specific CD4 T cells in small sample volumes.

Background Integrated cardiothoracic (CT) surgery training programs are an increasingly popular pathway to train CT surgeons. Identifying and engaging medical students early is important to generate interest and ensure highly qualified applicants are aware of opportunities provided by a career in CT surgery. Methods An optional CT surgery "mini-elective" was developed for preclinical medical students consisting of five 2-hour sessions covering major procedures in cardiac surgery. Each session had an inital 1 hour lecture immediatly followed by a hands on simulation component. Sessions were taught by CT surgery faculty and residents. A precourse and postcourse survey was administered to identify interest in and awareness of the field of CT surgery. Results There were 22 students enrolled in the course who provided precourse surveys, while 21 provided postcourse surveys. CT surgery was a career consideration for 95.4% of students who took the mini-elective. nine percent of the students who had either scrubbed or observed a CT case precourse, increased to 33.3% postcourse (P = .11). With regards to mentorship, 23.8% felt they could easily find a mentor in CT surgery precourse, increasing to 66.7% postcourse (P = .01). Eighty-one percent of students reported that the mini-elective significantly increased their CT knowledge over the standard cardiovascular curriculum, and 100% of those completing the course were "extremely satisfied" with the experience. Conclusions A CT surgery mini-elective increased awareness and interest in the field among preclinical medical students. Longitudinal exposure and mentorship provided in programs such as this will be key to the continued recruitment of high-quality medical students to the field.

Stroke is a major complication after cardiac surgery causing increased morbidity and mortality. There are limited data on outcomes of patients with large vessel occlusion after cardiac surgery.Patients who underwent index cardiac surgeries as defined by The Society of Thoracic Surgeons (STS) from 2010 to 2017 were reviewed from a prospectively maintained database. All patients with neurologic deficits were identified, and only patients with ischemic strokes were included.A total of 10,250 patients underwent cardiac surgical procedures. Postoperative stroke with neurologic deficits occurred in 221 patients (2.16%). Of these, 53 patients (24%) had large vessel occlusion. Patients who had a postoperative stroke were older and more likely to be female. These patients had higher STS predicted mortality and longer bypass time, cross-clamp time, total intensive care unit stay, and total hospital stay. Operative mortality was significantly higher for patients who had postoperative stroke (14.93% vs 2.15%, P.001). Kaplan-Meier survival estimates demonstrated worse survival for the large vessel occlusion cohort at 1 year (54.72% vs 75%, P = .002). Predictors of stroke included increasing age, known cerebrovascular disease, diabetes mellitus, and emergent operative status. The most significant predictors of operative mortality included emergent operative status and New York Heart Association stage IV heart failure. There was no difference in 30-day, 1-year, and 5-year mortality between the intervention group and the medically managed patients in the large vessel occlusion cohort.Stroke is a devastating complication after cardiac surgery that increases operative morbidity and mortality. Stroke with large vessel occlusion was associated with worse survival. However, early intervention did not impart a survival benefit.

Dengue disease is a large public health problem that mainly afflicts tropical and subtropical regions. Understanding of the correlates of protection against dengue virus (DENV) is poor and hinders the development of a successful human vaccine. The present study aims to define DENV-specific CD8 + T cell responses in general and those of HLA alleles associated with dominant responses in particular. In human blood donors in Nicaragua, we observed a striking dominance of HLA B-restricted responses in general and of the allele B*35:01 in particular. Comparing these patterns to those in the general population of Sri Lanka, we found a strong correlation between restriction of the HLA allele and the breadth and magnitude of CD8 + T cell responses, suggesting that HLA genes profoundly influence the nature of responses. The majority of gamma interferon (IFN-γ) responses were associated with effector memory phenotypes, which were also detected in non-B*35:01-expressing T cells. However, only the B*35:01 DENV-specific T cells were associated with marked expression of the programmed death 1 protein (PD-1). These cells did not coexpress other inhibitory receptors and were able to proliferate in response to DENV-specific stimulation. Thus, the expression of particular HLA class I alleles is a defining characteristic influencing the magnitude and breadth of CD8 responses, and a distinct, highly differentiated phenotype is specifically associated with dominant CD8 + T cells. These results are of relevance for both vaccine design and the identification of robust correlates of protection in natural immunity. IMPORTANCE Dengue is an increasingly significant public health problem as its mosquito vectors spread over greater areas; no vaccines against the virus have yet been approved. An important step toward vaccine development is defining protective immune responses; toward that end, we here characterize the phenotype of the immunodominant T cell responses. These DENV-reactive T cells express high levels of the receptor programmed death 1 protein (PD-1), while those from disease-susceptible alleles do not. Not only does this represent a possible correlate of immunodominance, but it raises the hypothesis that PD-1 might be a regulator that prevents excessive damage while preserving antiviral function. Further, as this study employs distinct populations (Nicaraguan and Sri Lankan donors), we also confirmed that this pattern holds despite geographic and ethnic differences. This finding indicates that HLA type is the major determinant in shaping T cell responses.

Case presentation A 12-year-old boy with no significant past medical imaging presented to the emergency department with 1 week of fever, sore throat, and left neck swelling. The patient was febrile with a leukocytosis and subsequently underwent contrast-enhanced computed tomography (CT) for further evaluation. Imaging findings Contrast-enhanced CT demonstrated a hypodense lesion with peripheral rim enhancement in the left tonsil, consistent with an abscess. There was extensive surrounding inflammation and surrounding edema. Additionally, there were central filling defects in the left internal and external jugular veins consistent with thrombosis. The apex of the lungs found bilateral peripherally based lung nodules that represented septic emboli. This was confirmed with subsequent dedicated CT chest. Discussion The constellation of peritonsillar abscess with associated thrombophlebitis of the jugular veins and pulmonary septic emboli is Lemierre's Syndrome. This is an uncommon and important diagnosis as it is life-threatening even with aggressive treatment (8% mortality) and the radiologist can often be the first to suggest the diagnosis. Classically the offending agent is the anaerobic gram-negative rod, Fusobacterium necophorum, although polymicrobial bacteremia is seen in up to a third of the cases. Cultures in the current case grew Streptococcus constellatus, a rare cause of Lemierre's Syndrome. Lemierre's Syndrome was first described in 1936 and is less commonly seen with the advent of antibiotics and thus also referred to as the ‘Forgotten Disease’, although there has been a reemergence more recently likely due to antibiotic resistance. It is most commonly seen in immunocompetent teenagers and young adults, more typically in males. Treatment includes antibiotics plus or minus abscess drainage and/or anticoagulation. Conclusions Lemierre's Syndrome has the classic imaging triad of ipsilateral pharyngeal fullness and neck vein thrombosis with pulmonary septic emboli. Our patient underwent a prolonged course of intravenous antibiotics with resolution of infection.

DNA sequence-based typing at the HLA-A, -B, -C, -DPB1, -DQA1, -DQB1, and -DRB1 loci was performed on 496 healthy adult donors from San Diego, California, to characterize allele frequencies in support of studies of T cell responses to common allergens. Deviations from Hardy Weinberg proportions were detected at each locus except A and C. Several alleles were found in more than 15% of individuals, including the class II alleles DPB1*02:01, DPB1*04:01, DQA1*01:02, DQA1 *05:01, DQB1*03:01, and the class I allele A*02:01. Genotype data will be available in the Allele Frequencies Net Database (AFND 3562).

Adipocytes are one of the major stromal cell components of the human breast. These cells play a key role in the development of the gland and are implicated in breast tumorigenesis. Frequently, directional stromal collagen I fibers are found surrounding aggressive breast tumors. These fibers enhance breast cancer cell migration and are associated with poor patient prognosis. We sought to recapitulate these stromal components in vitro to provide a three-dimensional (3D) model comprising human adipose tissue and anisotropic collagen fibers. We developed a human mesenchymal stem cell (hMSC) cell line capable of undergoing differentiation into mature adipocytes by immortalizing hMSCs, isolated from breast reduction mammoplasties, through retroviral transduction. These immortalized hMSCs were seeded in engineered collagen I scaffolds with directional internal architecture, and adipogenesis was chemically induced, resulting in human adipose tissue being synthesized in vitro in an architectural structure associated with breast tumorigenesis. Subsequently, fluorescently labeled cells from an established breast cancer cell line were seeded into this model, cocultured for 7 days and imaged using multiphoton microscopy. Enhanced breast cancer cell migration was observed in the adipose-containing model over empty scaffold controls, demonstrating an adipocyte-mediated influence on breast cancer cell migration. Thus, this 3D in vitro model recapitulates the migratory effects of adipocytes observed on breast cancer cells and suggests that it could have utility with fresh breast tumor biopsies as an assay for cancer therapeutic efficacy in personalized medicine strategies.

Lysosome function is essential in cellular homeostasis. In addition to its recycling role, the lysosome has recently been recognized as a cellular signaling hub. We have shown in mammary epithelial cells, both in vivo and in vitro, that signal transducer and activator of transcription 3 (Stat3) modulates lysosome biogenesis and can promote the release of lysosomal proteases that culminates in cell death. To further investigate the impact of Stat3 on lysosomal function, we conducted a proteomic screen of changes in lysosomal membrane protein components induced by Stat3 using an iron nanoparticle enrichment strategy. Our results show that Stat3 activation not only elevates the levels of known membrane proteins but results in the appearance of unexpected factors, including cell surface proteins such as annexins and flotillins. These data suggest that Stat3 may coordinately regulate endocytosis, intracellular trafficking, and lysosome biogenesis to drive lysosome-mediated cell death in mammary epithelial cells. The methodologies described in this study also provide significant improvements to current techniques used for the purification and analysis of the lysosomal proteome.

DNA sequence-based typing at the HLA-A, -B, -C, -DPB1, -DQA1, -DQB1, and -DRB1 loci was performed on 714 healthy adult blood bank donors from Colombo, Sri Lanka, to characterize allele frequencies in support of studies on T cell immunity against pathogens, including Dengue virus. Deviations from Hardy Weinberg proportions were not detected at any locus. Several alleles were found in >30% of individuals, including the class II alleles DPB1 * 04:01, DPB1 * 02:01, DQB1 * 06:01 and DRB1 * 07:01, and the class I alleles A * 33:03 and A * 24:02. Genotype data will be available in the Allele Frequencies Net Database.

Streptolysin O (SLO) is a bacterial pore forming protein that is part of the cholesterol dependent cytolysin (CDC) family. We have used quartz crystal microbalance with dissipation monitoring (QCM-D) to examine SLO membrane binding and pore formation. In this system, SLO binds tightly to cholesterol-containing membranes, and assembles into partial and complete pores confirmed by atomic force microscopy. SLO binds to the lipid bilayer at a single rate consistent with the Langmuir isotherm model of adsorption. Changes in dissipation illustrate that SLO alters the viscoelastic properties of the bilayer during pore formation, but there is no loss of material from the bilayer as reported for small membrane-penetrating peptides. SLO mutants were used to further dissect the assembly and insertion processes by QCM-D. This shows the signature of SLO in QCM-D changes when pore formation is inhibited, and that bound and inserted SLO forms can be distinguished. Furthermore a pre-pore locked SLO mutant binds reversibly to lipid, suggesting that the partially complete wtSLO forms observed by AFM are anchored to the membrane.

The vast amount of information found on the internet, combined with its accessibility, makes it a widely utilized resource for Americans to find information pertaining to medical information. The field of radiology is no exception. In this paper, we assess the readability level of websites pertaining specifically to emergency radiology. Using Google, 23 terms were searched, and the top 10 results were recorded. Each link was evaluated for its readability level using a set of ten reputable readability scales. The search terms included the following: abdominal ultrasound, abdominal aortic aneurysm, aortic dissection, appendicitis, cord compression, CT abdomen, cholecystitis, CT chest, diverticulitis, ectopic pregnancy, epidural hematoma, dural venous thrombosis, head CT, MRI brain, MR angiography, MRI spine, ovarian torsion, pancreatitis, pelvic ultrasound, pneumoperitoneum, pulmonary embolism, subarachnoid hemorrhage, and subdural hematoma. Any content that was not written for patients was excluded. The 230 articles that were assessed were written, on average, at a 12.1 grade level. Only 2 of the 230 articles (1%) were written at the third to seventh grade recommended reading level set forth by the National Institutes of Health (NIH) and American Medical Association (AMA). Fifty-two percent of the 230 articles were written so as to require a minimum of a high school education (at least a 12th grade level). Additionally, 17 of the 230 articles (7.3%) were written at a level that exceeded an undergraduate education (at least a 16th grade level). The majority of websites with emergency radiology-related patient education materials are not adhering to the NIH and AMA’s recommended reading levels, and it is likely that the average reader is not benefiting fully from these information outlets. With the link between health literacy and poor health outcomes, it is important to address the online content in this area of radiology, allowing for patient to more fully benefit from their online searches.

Dengue virus (DENV) is responsible for growing numbers of infections worldwide and has proven to be a significant challenge for vaccine development. We previously demonstrated that CD8 + T cell responses elicited by a dengue live attenuated virus (DLAV) vaccine resemble those observed after natural infection. In this study, we screened peripheral blood mononuclear cells (PBMCs) from donors vaccinated with a tetravalent DLAV vaccine (TV005) with pools of dengue virus-derived predicted major histocompatibility complex (MHC) class II binding peptides. The definition of CD4 + T cell responses after live vaccination is important because CD4 + T cells are known contributors to host immunity, including cytokine production, help for CD8 + T and B cells, and direct cytotoxicity against infected cells. While responses to all antigens were observed, DENV-specific CD4 + T cells were focused predominantly on the capsid and nonstructural NS3 and NS5 antigens. Importantly, CD4 + T cell responses in vaccinees were similar in magnitude and breadth to those after natural infection, recognized the same antigen hierarchy, and had similar profiles of HLA restriction. We conclude that TV005 vaccination has the capacity to elicit CD4 + cell responses closely mirroring those observed in a population associated with natural immunity. IMPORTANCE The development of effective vaccination strategies against dengue virus infection is of high global public health interest. Here we study the CD4 T cell responses elicited by a tetravalent live attenuated dengue vaccine and show that they resemble responses seen in humans naturally exposed to dengue virus. This is an important issue, since it is likely that optimal immunity induced by a vaccine requires induction of CD4 + responses against the same antigens as those recognized as dominant in natural infection. Detailed knowledge of the T cell response may further contribute to the identification of robust correlates of protection against dengue virus.

Background: Dengue is a major public health problem worldwide. Assessment of adaptive immunity is important to understanding immunopathology and to define correlates of protection against dengue virus (DENV). To enable global assessment of CD4+T cell responses, we mapped HLA-DRB1 restricted DENV-specific CD4+ T cell epitopes in individuals previously exposed to DENV in the general population of the dengue-endemic region of Managua, Nicaragua. Methods: HLA class II epitopes in the population of Managua were identified by an in vitro IFNγ ELISPOT assay. CD4+ T cells purified by magnetic bead negative selection were stimulated with HLA-matched epitope pools in the presence of autologous antigen presenting cells (APCs), followed by pool deconvolution to identify specific epitopes. The epitopes identified in this study were combined with those previously identified in the DENV endemic region of Sri Lanka, to generate a “megapool” (MP) consisting of 180 peptides specifically designed to achieve balanced HLA and DENV serotype coverage. The DENV CD4MP180 was validated by Intracellular Cytokine Staining (ICS) assays. Results: We detected responses directed against a total of 431 epitopes, representing all four DENV serotypes, restricted by 15 different HLA-DRB1 alleles. The responses were associated with a similar pattern of protein immunodominance, overall higher magnitude of responses, as compared to what was observed previously in the Sri Lanka region. Based on these epitope mapping studies, we designed a DENV CD4 MP180 with higher and more consistent coverage, which allowed the detection of CD4+ T cell DENV responses ex vivo in various cohorts of DENV exposed donors worldwide, including donors from Nicaragua, Brazil, Singapore, Sri Lanka and and U.S. domestic flavivirus-naive subjects immunized with Tetravalent Dengue Live Attenuated Vaccine (TV005). This broad reactivity reflects that the 21 HLA-DRB1 alleles analyzed in this and previous studies account for more than 80% of alleles present with a phenotypic frequency ≥ 5% worldwide, corresponding to 92% phenotypic coverage of the general population (i.e., 92% of individuals express at least one of these alleles). Conclusion: The DENV CD4 MP180 can be utilized to measure ex vivo responses to DENV irrespective of geographical location.

Dengue virus (DENV) is the causative agent of dengue fever (DF). This disease can be caused by any of four DENV serotypes (DENV1 to -4) which share 67 to 75% sequence homology with one another. The effect of subsequent infections with different serotypes on the T cell repertoire is not fully understood. We utilized mice transgenic for human leukocyte antigens (HLA) lacking the alpha/beta interferon (IFN-α/β) receptor to study responses to heterologous DENV infection. First, we defined the primary T cell response to DENV3 in the context of a wide range of HLA molecules. The primary DENV3 immune response recognized epitopes derived from all 10 DENV proteins, with a significant fraction of the response specific for structural proteins. This is in contrast to primary DENV2 infection, in which structural proteins are a minor component of the response, suggesting differential antigen immunodominance as a function of the infecting serotype. We next investigated the effect of secondary heterologous DENV infection on the T cell repertoire. In the case of both DENV2/3 and DENV3/2 heterologous infections, recognition of conserved/cross-reactive epitopes was either constant or expanded compared to that in homologous infection. Furthermore, in heterologous infection, previous infection with a different serotype impaired the development of responses directed to serotype-specific but not conserved epitopes. Thus, a detrimental effect of previous heterotypic responses might not be due to dysfunctional and weakly cross-reactive epitopes dominating the response. Rather, responses to the original serotype might limit the magnitude of responses directed against epitopes that are either cross-reactive to or specific for the most recently infecting serotype. IMPORTANCE DENV transmission occurs in more than 100 countries and is an increasing public health problem in tropical and subtropical regions. At present, no effective antiviral therapy or licensed vaccine exists, and treatment is largely supportive in nature. Disease can be caused by any of the four DENV serotypes (DENV1 to -4), which share a high degree of sequence homology with one another. In this study, we have addressed the question of how the T cell repertoire changes as a function of infections with different serotypes and of subsequent heterologous secondary infections. This is of particular interest in the field of dengue viruses, in which secondary infections with different DENV serotypes increase the risk of severe disease. Our results on the evolution of the immune response after primary and secondary infections provide new insights into HLA-restricted T cell responses against DENV relevant for the design of a vaccine against DENV.

Cytotoxic lymphocytes eliminate virally infected or neoplastic cells through the action of cytotoxic proteases (granzymes). The pore-forming protein perforin is essential for delivery of granzymes into the cytoplasm of target cells; however the mechanism of this delivery is incompletely understood. Perforin contains a membrane attack complex/perforin (MACPF) domain and oligomerizes to form an aqueous pore in the plasma membrane; therefore the simplest (and best supported) model suggests that granzymes passively diffuse through the perforin pore into the cytoplasm of the target cell. Here we demonstrate that perforin preferentially delivers cationic molecules while anionic and neutral cargoes are delivered inefficiently. Furthermore, another distantly related pore-forming MACPF protein, pleurotolysin (from the oyster mushroom), also favors the delivery of cationic molecules, and efficiently delivers human granzyme B. We propose that this facilitated diffusion is due to conserved features of oligomerized MACPF proteins, which may include an anionic lumen.

DNA sequence-based typing at the HLA-A, -B, -C, -DPB1, -DQA1, -DQB1, and -DRB1 loci was performed on anonymized samples provided by 339 healthy adult blood bank donors in Managua, Nicaragua. The purpose of the study was to characterize allele frequencies in the local population to support studies of T cell immunity against pathogens, including Dengue virus. Deviations from Hardy Weinberg proportions were detected for all class II loci (HLA-DPB1, -DQA1, -DQB1 and -DRB1), and at the class I C locus, but not at the class I A and B loci. The genotype data will be available in the Allele Frequencies Net Database.

A deletion variant of the dengue virus (DENV) serotype 2 (DENV2) Tonga/74 strain lacking 30 nucleotides from its 3′ untranslated region (rDEN2Δ30) has previously been established for use in a controlled human DENV challenge model. To evaluate if this model is appropriate for the derivation of correlates of protection for DENV vaccines on the basis of cellular immunity, we wanted to compare the cellular immune response to this challenge strain to the response induced by natural infection. To achieve this, we predicted HLA class I- and class II-restricted peptides from rDEN2Δ30 and used them in a gamma interferon enzyme-linked immunosorbent spot assay to interrogate CD8 + and CD4 + T cell responses in healthy volunteers infected with rDEN2Δ30. At the level of CD8 responses, vigorous ex vivo responses were detected in approximately 80% of donors. These responses were similar in terms of the magnitude and the numbers of epitopes recognized to the responses previously observed in peripheral blood mononuclear cells from donors from regions where DENV is hyperendemic. The similarity extended to the immunodominance hierarchy of the DENV nonstructural proteins, with NS3, NS5, and NS1 being dominant in both donor cohorts. At the CD4 level, the responses to rDEN2Δ30 vaccination were less vigorous than those to natural DENV infection and were more focused on nonstructural proteins. The epitopes recognized following rDEN2Δ30 infection and natural infection were largely overlapping for both the CD8 (100%) and CD4 (85%) responses. Finally, rDEN2Δ30 induced stronger CD8 responses than other, more attenuated DENV isolates. IMPORTANCE The lack of a known correlate of protection and the failure of a neutralizing antibody to correlate with protection against dengue virus have highlighted the need for a human DENV challenge model to better evaluate the candidate live attenuated dengue vaccines. In this study, we sought to characterize the immune profiles of rDEN2Δ30-infected subjects and to compare the profiles with those for subjects from areas where DENV is hyperendemic. Our data demonstrate that T cell responses to rDENV2Δ30 are largely similar to those to natural infection in terms of specificity, highlighting that the response to this virus in humans is appropriate as a model for the T cell response to primary DENV2 infection.

Dengue virus (DENV) is responsible for growing numbers of infections worldwide and has proven to be a significant challenge for vaccine development. We previously demonstrated that CD8+ T cell responses elicited by a dengue live attenuated virus (DLAV) vaccine resemble those observed after natural infection. In this study, we screened peripheral blood mononuclear cells (PBMCs) from donors vaccinated with a tetravalent DLAV vaccine (TV005) with pools of dengue virus-derived predicted major histocompatibility complex (MHC) class II binding peptides. The definition of CD4+ T cell responses after live vaccination is important because CD4+ T cells are known contributors to host immunity, including cytokine production, help for CD8+ T and B cells, and direct cytotoxicity against infected cells. While responses to all antigens were observed, DENV-specific CD4+ T cells were focused predominantly on the capsid and nonstructural NS3 and NS5 antigens. Importantly, CD4+ T cell responses in vaccinees were similar in magnitude and breadth to those after natural infection, recognized the same antigen hierarchy, and had similar profiles of HLA restriction. We conclude that TV005 vaccination has the capacity to elicit CD4+ cell responses closely mirroring those observed in a population associated with natural immunity.

Background. Each year dengue virus (DENV) infects 400 million human but causes symptomatic disease in only a subset of patients, suggesting that host genetic factors may play a role. HLA molecules that restrict T-cell responses are one of the most polymorphic host factors in humans. Methods. Here we map HLA DRB1–restricted DENV-specific epitopes in individuals previously exposed to DENV, to identify the breadth and specificity of CD4+ T-cell responses. To investigate whether HLA-specific variations in the magnitude of response might predict associations between dengue outcomes and HLA-DRB1 alleles, we assembled samples from hospitalized patients with known severity of disease. Results. The capsid protein followed by nonstructural protein 3 (NS3), NS2A, and NS5 were the most targeted proteins. We further noticed a wide variation in magnitude of T-cell responses as a function of the restricting DRB1 allele and found several HLA alleles that showed trends toward a lower risk of hospitalized disease were associated with a higher magnitude of T-cell responses. Conclusions. Comprehensive identification of unique CD4+ T-cell epitopes across the 4 DENV serotypes allows the testing of T-cell responses by use of a simple, approachable technique and points to important implications for vaccine design.

The new NFPA 99 Security Management Standard for healthcare facilities requires a Security Vulnerability Analysis be conducted annually, the author reports. This will usually uncover little change from year to year, he says, but by using the right model the analysis can be used to win back security additions that had previously been rejected by the C-Suite.

Cytotoxic lymphocytes (CLs) are responsible for the clearance of virally infected or neoplastic cells. CLs possess specialised lysosome-related organelles called granules which contain the granzyme family of serine proteases and perforin. Granzymes may induce apoptosis in the target cell when delivered by the pore forming protein, perforin. Here we follow the perforin-granzyme pathway from synthesis and storage in the granule, to exocytosis and finally delivery into the target cell. This review focuses on the controversial subject of perforin-mediated translocation of granzymes into the target cell cytoplasm. It remains unclear whether this occurs at the cell surface with granzymes moving through a perforin pore in the plasma membrane, or if it involves internalisation of perforin and granzymes and subsequent release from an endocytic compartment. The latter mechanism would represent an example of cross talk between the endo-lysosomal pathways of individual cells. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.

The frequency of dengue virus (DENV) infection has increased dramatically in the last few decades, and the lack of a vaccine has led to significant morbidity and mortality worldwide. To date, a convenient murine system to study human T cell responses to DENV has not been available. Mice transgenic for HLA are widely used to model human immune responses, and it has been shown that mouse-passaged DENV is able to replicate to significant levels in IFN-α/βR−/− mice. To cover a wide range of HLA phenotypes, we backcrossed IFN-α/βR−/− mice with HLA A*0201, A*0101, A*1101, B*0702, and DRB1*0101-transgenic mice. A DENV proteome-wide screen identified a total of 42 epitopes across all HLA-transgenic IFN-α/βR−/− strains tested. In contrast, only eight of these elicited responses in the corresponding IFN-α/βR+/+ mice. We were able to identify T cell epitopes from 9 out of the 10 DENV proteins. However, the majority of responses were derived from the highly conserved nonstructural proteins NS3 and NS5. The relevance of this model is further demonstrated by the fact that most of the epitopes identified in our murine system are also recognized by PBMC from DENV-exposed human donors, and a dominance of HLA B*0702-restricted responses has been detected in both systems. Our results provide new insights into HLA-restricted T cell responses against DENV, and we describe in this study a novel murine model that allows the investigation of T cell-mediated immune mechanisms relevant to vaccine design.

Natural killer cells and cytotoxic T lymphocytes accomplish the critically important function of killing virus-infected and neoplastic cells. They do this by releasing the pore-forming protein perforin and granzyme proteases from cytoplasmic granules into the cleft formed between the abutting killer and target cell membranes. Perforin, a 67-kilodalton multidomain protein, oligomerizes to form pores that deliver the pro-apoptopic granzymes into the cytosol of the target cell. The importance of perforin is highlighted by the fatal consequences of congenital perforin deficiency, with more than 50 different perforin mutations linked to familial haemophagocytic lymphohistiocytosis (type 2 FHL). Here we elucidate the mechanism of perforin pore formation by determining the X-ray crystal structure of monomeric murine perforin, together with a cryo-electron microscopy reconstruction of the entire perforin pore. Perforin is a thin 'key-shaped' molecule, comprising an amino-terminal membrane attack complex perforin-like (MACPF)/cholesterol dependent cytolysin (CDC) domain followed by an epidermal growth factor (EGF) domain that, together with the extreme carboxy-terminal sequence, forms a central shelf-like structure. A C-terminal C2 domain mediates initial, Ca(2+)-dependent membrane binding. Most unexpectedly, however, electron microscopy reveals that the orientation of the perforin MACPF domain in the pore is inside-out relative to the subunit arrangement in CDCs. These data reveal remarkable flexibility in the mechanism of action of the conserved MACPF/CDC fold and provide new insights into how related immune defence molecules such as complement proteins assemble into pores.

Perforin is an essential component in the cytotoxic lymphocyte-mediated cell death pathway. The traditional view holds that perforin monomers assemble into pores in the target cell membrane via a calcium-dependent process and facilitate translocation of cytotoxic proteases into the cytoplasm to induce apoptosis. Although many studies have examined the structure and role of perforin, the mechanics of pore assembly and granzyme delivery remain unclear. Here we have employed quartz crystal microbalance with dissipation monitoring (QCM-D) to investigate binding and assembly of perforin on lipid membranes, and show that perforin monomers bind to the membrane in a cooperative manner. We also found that cholesterol influences perforin binding and activity on intact cells and model membranes. Finally, contrary to current thinking, perforin efficiently binds membranes in the absence of calcium. When calcium is added to perforin already on the membrane, the QCM-D response changes significantly, indicating that perforin becomes membranolytic only after calcium binding.