BACKGROUND Metagenomic next-generation sequencing (NGS) of cerebrospinal fluid (CSF) has the potential to identify a broad range of pathogens in a single test. METHODS In a 1-year, multicenter, prospective study, we investigated the usefulness of metagenomic NGS of CSF for the diagnosis of infectious meningitis and encephalitis in hospitalized patients. All positive tests for pathogens on metagenomic NGS were confirmed by orthogonal laboratory testing. Physician feedback was elicited by teleconferences with a clinical microbial sequencing board and by surveys. Clinical effect was evaluated by retrospective chart review. RESULTS We enrolled 204 pediatric and adult patients at eight hospitals. Patients were severely ill: 48.5% had been admitted to the intensive care unit, and the 30-day mortality among all study patients was 11.3%. A total of 58 infections of the nervous system were diagnosed in 57 patients (27.9%). Among these 58 infections, metagenomic NGS identified 13 (22%) that were not identified by clinical testing at the source hospital. Among the remaining 45 infections (78%), metagenomic NGS made concurrent diagnoses in 19. Of the 26 infections not identified by metagenomic NGS, 11 were diagnosed by serologic testing only, 7 were diagnosed from tissue samples other than CSF, and 8 were negative on metagenomic NGS owing to low titers of pathogens in CSF. A total of 8 of 13 diagnoses made solely by metagenomic NGS had a likely clinical effect, with 7 of 13 guiding treatment. CONCLUSIONS Routine microbiologic testing is often insufficient to detect all neuroinvasive pathogens. In this study, metagenomic NGS of CSF obtained from patients with meningitis or encephalitis improved diagnosis of neurologic infections and provided actionable information in some cases. (Funded by the National Institutes of Health and others; PDAID ClinicalTrials.gov number, .)

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Chlamydiae are obligate intracellular bacteria that replicate within an inclusion that is trafficked to the periGolgi region where it fuses with exocytic vesicles. The host and chlamydial proteins that regulate the trafficking of the inclusion have not been identified. Since Rab GTPases are key regulators of membrane trafficking, we examined the intracellular localization of several green fluorescent protein (GFP)-tagged Rab GTPases in chlamydia-infected HeLa cells. GFP-Rab4 and GFP-Rab11, which function in receptor recycling, and GFPRab1, which functions in endoplasmic reticulum (ER)-to-Golgi trafficking, are recruited to Chlamydia trachomatis, Chlamydia muridarum, and Chlamydia pneumoniae inclusions, whereas GFP-Rab5, GFP-Rab7, and GFPRab9, markers of early and late endosomes, are not. In contrast, GFP-Rab6, which functions in Golgi-to-ER and endosome-to-Golgi trafficking, is associated with C. trachomatis inclusions but not with C. pneumoniae or C. muridarum inclusions, while the opposite was observed for the Golgi-localized GFP-Rab10. Colocalization studies between transferrin and GFP-Rab11 demonstrate that a portion of GFP-Rab11 that localizes to inclusions does not colocalize with transferrin, which suggests that GFP-Rab11's association with the inclusion is not mediated solely through Rab11's association with transferrin-containing recycling endosomes. Finally, GFP-Rab GTPases remain associated with the inclusion even after disassembly of microtubules, which disperses recycling endosomes and the Golgi apparatus within the cytoplasm, suggesting a specific interaction with the inclusion membrane. Consistent with this, GFP-Rab11 colocalizes with C. trachomatis IncG at the inclusion membrane. Therefore, chlamydiae recruit key regulators of membrane trafficking to the inclusion, which may function to regulate the trafficking or fusogenic properties of the inclusion.Chlamydiae are major bacterial pathogens of ocular, urogenital, and pulmonary mucosal surfaces (51). Infections caused by Chlamydia trachomatis are the leading cause of bacterially acquired sexually transmitted disease (10), as well as of preventable blindness worldwide (64). In addition, Chlamydia pneumoniae infections are major causes of upper respiratory tract infections and have recently been linked to chronic heart disease (24, 25). Chlamydiae are obligate intracellular bacteria that replicate within a nonacidified vacuole termed an inclusion (26). Within the inclusion, chlamydiae undergo a biphasic developmental cycle that alternates between the infectious metabolically inactive elementary body (EB) and the noninfectious metabolically active reticulate body (40). Although chlamydiae enter nonprofessional phagocytes by multiple mechanisms (reviewed in reference 26), once the chlamydiae are internalized, they actively modify the properties of the nascent vacuole during the first 2 h postinfection, resulting in trafficking of the inclusion to the peri-Golgi region, fusion of the inclusion with a subset of Golgi-derived exocytic vesicles, and avoi...

Vesicular stomatitis virus (VSV) is well established to enter cells by pH-dependent endocytosis, but mechanistic aspects of its internalization have remained unclear. Here, we examined the functional role of clathrin in VSV entry by expression of a dominant-negative mutant of Eps15 (GFP-Eps15Delta95/295), a protein essential for clathrin-mediated endocytosis. Whereas expression of GFP alone had no effect on VSV infection, expression of GFP-Eps15Delta95/295 severely limited infection. As independent ways to examine clathrin function, we also examined cells that had been treated with chlorpromazine and utilized small interfering RNA (siRNA) techniques. Inhibition of clathrin-mediated endocytosis by chlorpromazine treatment, as well as clathrin knock-down using siRNA duplexes directed against the clathrin heavy chain, also prevented VSV infection. In combination with previous morphological approaches, these experiments establish clathrin as an essential component needed for endocytosis of VSV.

Polyclonal rATG induces complement-independent apoptosis of naive, activated, and plasma B cells. This effect appears to involve the caspase- and cathepsin-mediated apoptosis pathways.

Objectives: Genetic disorders are a leading contributor to mortality in the neonatal ICU and PICU in the United States. Although individually rare, there are over 6,200 single-gene diseases, which may preclude a genetic diagnosis prior to ICU admission. Rapid whole genome sequencing is an emerging method of diagnosing genetic conditions in time to affect ICU management of neonates; however, its clinical utility has yet to be adequately demonstrated in critically ill children. This study evaluates next-generation sequencing in pediatric critical care. Design: Retrospective cohort study. Setting: Single-center PICU in a tertiary children’s hospital. Patients: Children 4 months to 18 years admitted to the PICU who were nominated between July 2016 and May 2018. Interventions: Rapid whole genome sequencing with targeted phenotype-driven analysis was performed on patients and their parents, when parental samples were available. Measurements and Main Results: A molecular diagnosis was made by rapid whole genome sequencing in 17 of 38 children (45%). In four of the 17 patients (24%), the genetic diagnoses led to a change in management while in the PICU, including genome-informed changes in pharmacotherapy and transition to palliative care. Nine of the 17 diagnosed children (53%) had no dysmorphic features or developmental delay. Eighty-two percent of diagnoses affected the clinical management of the patient and/or family after PICU discharge, including avoidance of biopsy, administration of factor replacement, and surveillance for disorder-related sequelae. Conclusions: This study demonstrates a retrospective evaluation for undiagnosed genetic disease in the PICU and clinical utility of rapid whole genome sequencing in a portion of critically ill children. Further studies are needed to identify PICU patients who will benefit from rapid whole genome sequencing early in PICU admission when the underlying etiology is unclear.

Since 2012, the United States has experienced a biennial spike in pediatric acute flaccid myelitis (AFM). 1-6 Epidemiologic evidence suggests non-polio enteroviruses (EVs) are a potential etiology, yet EV RNA is rarely detected in cerebrospinal fluid (CSF). 2 We interrogated CSF from children with AFM (n=42) and pediatric other neurologic disease controls (n=58) for intrathecal anti-viral antibodies using a phage display library expressing 481,966 overlapping peptides derived from all known vertebrate and arboviruses (VirScan). We also performed metagenomic next-generation sequencing (mNGS) of AFM CSF RNA (n=20 cases), both unbiased and with targeted enrichment for EVs. Using VirScan, the only viral family significantly enriched by the CSF of AFM cases relative to controls was Picornaviridae, with the most enriched Picornaviridae peptides belonging to the genus Enterovirus (n=29/42 cases versus 4/58 controls). EV VP1 ELISA confirmed this finding (n=22/26 cases versus 7/50 controls). mNGS did not detect additional EV RNA. Despite rare detection of EV RNA, pan-viral serology identified frequently high levels of CSF EV-specific antibodies in AFM compared to controls, providing further evidence for a causal role of non-polio EVs in AFM.

A striking characteristic of a Rab protein is its steady-state localization to the cytosolic surface of a particular subcellular membrane. In this study, we have undertaken a combined bioinformatic and experimental approach to examine the evolutionary conservation of Rab protein localization. A comprehensive primary sequence classification shows that 10 out of the 11 Rab proteins identified in the yeast (Saccharomyces cerevisiae) genome can be grouped within a major subclass, each comprising multiple Rab orthologs from diverse species. We compared the locations of individual yeast Rab proteins with their localizations following ectopic expression in mammalian cells. Our results suggest that green fluorescent protein-tagged Rab proteins maintain localizations across large evolutionary distances and that the major known player in the Rab localization pathway, mammalian Rab-GDI, is able to function in yeast. These findings enable us to provide insight into novel gene functions and classify the uncharacterized Rab proteins Ypt10p (YBR264C) as being involved in endocytic function and Ypt11p (YNL304W) as being localized to the endoplasmic reticulum, where we demonstrate it is required for organelle inheritance.All eukaryotic cells are compartmentalized into distinct membrane-bound organelles and require tightly regulated transport of proteins and lipids between these compartments. Members of the Rab family of small GTPases are major regulators of protein and lipid traffic in the secretory and endocytic pathways (46,65). The action of Rab proteins in membrane transport was discovered with the identification of the SEC4 and YPT1 genes in yeast (Saccharomyces cerevisiae) (51, 52) and related proteins, termed Rab proteins, from mammals (10). Rab proteins comprise the most numerous subfamily of the Ras superfamily, and many are functionally uncharacterized. It is not clear whether Rab proteins regulate events that take place in the donor compartment, the vesicle or transport carrier, the acceptor compartment, or multiple locations. Also not known is whether a function(s) can be described for Rab proteins in general or whether this must be considered on a case-by-case basis. However, it is clear that Rab proteins are essential for eukaryotic cells and absolutely required for the function of all organelles connected by SNARE-mediated membrane traffic.With the completion of eukaryotic genome sequencing projects, there have been efforts to catalog the numbers of GTPase superfamily proteins. Membrane traffic in higher eukaryotes connects multiple compartments, and one reflection of this complexity may be the finding that humans have at least 60 different Rab family members (24,55,57). Other eukaryotes have fewer Rab proteins; Caenorhabditis elegans has 29 family members, Drosophila melanogaster has 26 members, and the yeast Saccharomyces cerevisiae has 11 members. As a model system, the 11 Rab proteins of the single-celled eukaryotic microbe S. cerevisiae can be considered the most minimal "membrome" (24), as other single-celle...