Antibodies Produced in Response to a Live-Attenuated Dengue Vaccine Are Functional in Activating the Complement System.

BACKGROUND: Antibody-driven complement system (CS) activation has been associated with protection against symptomatic dengue virus (DENV) infection. Aggregation, opsonization, lysis, and phagocytosis are mechanisms triggered by antibody-antigen immunocomplexes following fixation of the component 1q (C1q) and activation of the classical pathway. As a result, DENV neutralization and clearance are facilitated, whereas antibody-dependent enhancement of infection is inhibited. We investigated the ability of antibodies produced in response to Takeda's dengue vaccine candidate, TAK-003, to fix C1q and activate CS. METHODS: Serum samples were collected from seronegative and seropositive participants in a phase 2 clinical trial (DEN-203), pre- and postvaccination. Samples were evaluated for the presence of complement-fixing antibodies (CFAs) against DENV using a Luminex multiplex-based immunoassay. RESULTS: TAK-003 elicited production of CFAs against all 4 DENV serotypes, which persisted for 1 year postvaccination, irrespective of baseline serostatus. CFA levels were correlated with neutralizing antibody titers and virus-binding total IgG and IgG1 concentrations. Furthermore, efficiency of CFA fixation was greater in samples with higher polyclonal IgG avidity. CONCLUSIONS: These results indicate that antibodies produced after TAK-003 vaccination are functional in both activating CS and neutralizing virus infection by all DENV serotypes, which may contribute to efficacy of TAK-003. CLINICAL TRIALS REGISTRATION: NCT01511250.

Characterization of the Type-Specific and Cross-Reactive B-Cell Responses Elicited by a Live-Attenuated Tetravalent Dengue Vaccine.

BACKGROUND: Dengue is caused by 4 antigenically distinct serotypes of dengue virus (DENV1-4). Takeda's live attenuated tetravalent dengue vaccine (TAK-003) candidate is composed of an attenuated DENV2 and chimeric viruses containing prM/E of DENV1, 3 and 4 on the DENV2 backbone. The multicolor FluoroSpot (MCF) assay enables quantitation of serotype-specific and cross-reactive individual memory B cells (MBCs) secreting DENV-specific antibodies in a polyclonal mixture. METHODS: Using the MCF assay, we determined the type-specific and cross-reactive MBC response in peripheral blood mononuclear cells collected pre- and postvaccination from 7 macaques and 15 randomly selected individuals who received TAK-003 (8 DENV seronegative and 7 DENV seropositive) in a phase 2 clinical trial in Singapore (DEN-205 study). RESULTS: Preexisting DENV-specific MBC responses were detected only in seropositive vaccine recipients at day 0. Following vaccination, both type-specific and cross-reactive MBCs to all 4 DENV serotypes were observed in all macaques and clinical trial participants. The proportion of type-specific MBCs was higher than cross-reactive MBCs and remained stable between day 30 and 360 post vaccination. CONCLUSIONS: These results demonstrate that, unlike primary or secondary natural DENV infection, tetravalent vaccination elicits tetravalent type-specific MBCs, and thus all 4 components of TAK-003 contribute to the DENV-specific MBC response following vaccination. CLINICAL TRIALS REGISTRATION: NCT02425098.

Development and Characterization of a Multiplex Assay to Quantify Complement-Fixing Antibodies against Dengue Virus.

Antibodies capable of activating the complement system (CS) when bound with antigen are referred to as "complement-fixing antibodies" and are involved in protection against Flaviviruses. A complement-fixing antibody test has been used in the past to measure the ability of dengue virus (DENV)-specific serum antibodies to activate the CS. As originally developed, the test is time-consuming, cumbersome, and has limited sensitivity for DENV diagnosis. Here, we developed and characterized a novel multiplex anti-DENV complement-fixing assay based on the Luminex platform to quantitate serum antibodies against all four serotypes (DENV1-4) that activate the CS based on their ability to fix the complement component 1q (C1q). The assay demonstrated good reproducibility and showed equivalent performance to a DENV microneutralization assay that has been used to determine DENV serostatus. In non-human primates, antibodies produced in response to primary DENV1-4 infection induced C1q fixation on homologous and heterologous serotypes. Inter-serotype cross-reactivity was associated with homology of the envelope protein. Interestingly, the antibodies produced following vaccination against Zika virus fixed C1q on DENV. The anti-DENV complement fixing antibody assay represents an alternative approach to determine the quality of functional antibodies produced following DENV natural infection or vaccination and a biomarker for dengue serostatus, while providing insights about immunological cross-reactivity among different Flaviviruses.

A Case of Prolapsed Gastropathy Syndrome Presenting as Hematemesis and Acute Blood Loss Anemia.

A 45-year-old male with hypertension and alcohol use disorder presented to the hospital after being found intoxicated, with bright red blood in the toilet and around his mouth. He was found to be tachycardiac and required intubation due to his inebriated state to establish a secure airway. Initial workup revealed a hemoglobin decrease from 16.7 g/dL to 8.7 g/dL, as well as lactic acidosis. He quickly underwent an upper endoscopy to evaluate his source of hematemesis. An actively bleeding lesion was found in the proximal stomach consistent with prolapse gastropathy syndrome. This case highlights a unique presentation of hematemesis that requires endoscopic evaluation for both diagnosis and treatment.

A connectivity model of the anatomic substrates underlying ideomotor apraxia: A meta-analysis of functional neuroimaging studies.

BACKGROUND: Patients with ideomotor apraxia (IMA) present with selective impairments in higher-order motor cognition and execution without damage to any motor or sensory pathways. Although extensive research has been conducted to determine the regions of interest (ROIs) underlying these unique impairments, previous models are heterogeneous and may be further clarified based on their structural connectivity, which has been far less described. OBJECTIVE: The goal of this research is to propose an anatomically concise network model for the neurophysiologic basis of IMA, specific to the voluntary pantomime, imitation and tool execution, based on intrinsic white matter connectivity. METHODS: We utilized meta-analytic software to identify relevant ROIs in ideomotor apraxia as reported in the literature based on functional neuroimaging data with healthy participants. After generating an activation likelihood estimation (ALE) of relevant ROIs, cortical parcellations overlapping the ALE were used to construct an anatomically precise model of anatomic substrates using the parcellation scheme outlined by the Human Connectome Project (HCP). Deterministic tractography was then performed on 25 randomly selected, healthy HCP subjects to determine the structural connectivity underlying the identified ROIs. RESULTS: 10 task-based fMRI studies met our inclusion criteria and the ALE analysis demonstrated 6 ROIs to constitute the IMA network: SCEF, FOP4, MIP, AIP, 7AL, and 7PC. These parcellations represent a fronto-parietal network consisting mainly of intra-parietal, U-shaped association fibers (40%) and long-range inferior fronto-occipital fascicle (IFOF) fibers (50%). These findings support previous functional models based on dual-stream motor processing. CONCLUSION: We constructed a preliminary model demonstrating the underlying structural interconnectedness of anatomic substrates involved in higher-order motor functioning which is seen impaired in IMA. Our model provides support for previous dual-stream processing frameworks discussed in the literature, but further clarification is necessary with voxel-based lesion studies of IMA to further refine these findings.

Hepatic Dysfunction as a Paraneoplastic Manifestation of Metastatic Prostate Adenocarcinoma.

Cholestasis is a general feature of intrahepatic or extrahepatic biliary obstruction by various mechanisms including cirrhosis, stricture, choledocholithiasis, hepatitis, and neoplasms. Neoplasms can directly impinge on the hepatobiliary tree resulting in bile stasis. Stauffer's syndrome is another variant of this neoplastic process that can cause cholestasis and liver enzyme elevation without any direct hepatobiliary obstruction, and is thus categorized as a paraneoplastic syndrome of unclear pathophysiology. We report a first case of metastatic prostate adenocarcinoma with features of Stauffer's syndrome that reversed completely on androgen deprivation therapy. This is in contrast to a previously reported case of Stauffer's syndrome due to metastatic prostate adenocarcinoma, which reversed partially to androgen deprivation therapy. Our case demonstrates the importance of early recognition of Stauffer's syndrome and underlying neoplasms in patients who present with cholestasis without clear evidence of intrahepatic or extrahepatic biliary obstruction, which may lead to early initiation of treatment.

Safety of band ligator use in the small bowel and the colon.

BACKGROUND: Endoscopic band ligation for bleeding small-bowel vascular lesions has been reported as safe and efficacious based on small case series. There have been several other published case reports of band ligators used for bleeding lesions, usually Dieulafoy's lesions, in the stomach, the proximal small bowel, and the colon. In addition, this method has been used for postpolypectomy bleeding stalks. There has never been a critical look at the anatomic consequences of banding in the thinner sections of bowel. METHOD: The purpose of this study is to define the anatomic and histologic consequences of applying band ligator devices to the small and the large bowel. Fresh surgical specimens, both large and small bowel, that were excised because of neoplastic lesions were transported to our endoscopy unit where one end of the intact bowel was sutured shut. A standard upper endoscope was passed via the open end, and the bowel was closed tightly with rubber band ties. The bowel then was insufflated, and band ligators were applied to unaffected mucosa by using a standard technique. Photodocumentation from inside and outside the bowel was obtained. Some of the band polyps were cut above the band, and some were cut below the band in the fresh state. Some were fixed in formalin and examined microscopically. Histologic sectioning occurred at the level of the bands. RESULTS: The results were striking in that there were large holes (1 cm) in the fresh ileum specimen. There was gross serosal entrapment manifested by visible puckers on the outer surfaces of the specimens, especially in the small bowel and the right colon. The left colon, anatomically thicker, was less affected. The histologic evaluation revealed inclusion by the band ligator of the muscularis propria and serosa on the small bowel, the muscularis propria in the right colon, and the submucosa in the left colon. CONCLUSIONS: Based on these findings, we conclude that band ligator devices are not safe in the small bowel and the right colon but probably are safe in the thicker left colon.