Medical Genetics Commons^™

Intracellular Bacteria Encode Inhibitory Snare-Like Proteins., Fabienne Paumet, Jordan Wesolowski, Alejandro Garcia-Diaz, Cedric Delevoye, Nathalie Aulner, Howard A Shuman, Agathe Subtil, James E Rothman

Fabienne Paumet

Pathogens use diverse molecular machines to penetrate host cells and manipulate intracellular vesicular trafficking. Viruses employ glycoproteins, functionally and structurally similar to the SNARE proteins, to induce eukaryotic membrane fusion. Intracellular pathogens, on the other hand, need to block fusion of their infectious phagosomes with various endocytic compartments to escape from the degradative pathway. The molecular details concerning the mechanisms underlying this process are lacking. Using both an in vitro liposome fusion assay and a cellular assay, we showed that SNARE-like bacterial proteins block membrane fusion in eukaryotic cells by directly inhibiting SNARE-mediated membrane fusion. More specifically, we showed that …

Rip1-Dependent And Independent Effects Of Necrostatin-1 In Necrosis And T Cell Activation., Youngsik Cho, Thomas Mcquade, Haibing Zhang, Jianke Zhang, Francis Ka-Ming Chan

Department of Microbiology and Immunology Faculty Papers

BACKGROUND: Programmed necrosis/necroptosis is an emerging form of cell death that plays important roles in mammalian development and the immune system. The pro-necrotic kinases in the receptor interacting protein (RIP) family are crucial mediators of programmed necrosis. Recent advances in necrosis research have been greatly aided by the identification of chemical inhibitors that block programmed necrosis. Necrostatin-1 (Nec-1) and its derivatives were previously shown to target the pro-necrotic kinase RIP1/RIPK1. The protective effect conferred by Nec-1 and its derivatives in many experimental model systems was often attributed to the inhibition of RIP1 function.

METHODOLOGY/PRINCIPAL FINDINGS: We compared the effect of …

Microarray-Based Analysis Of Differential Gene Expression Between Infective And Noninfective Larvae Of Strongyloides Stercoralis., Roshan Ramanathan, Sudhir Varma, José M C Ribeiro, Timothy G Myers, Thomas J Nolan, David Abraham, James B Lok, Thomas B Nutman

Department of Microbiology and Immunology Faculty Papers

BACKGROUND: Differences between noninfective first-stage (L1) and infective third-stage (L3i) larvae of parasitic nematode Strongyloides stercoralis at the molecular level are relatively uncharacterized. DNA microarrays were developed and utilized for this purpose.

METHODS AND FINDINGS: Oligonucleotide hybridization probes for the array were designed to bind 3,571 putative mRNA transcripts predicted by analysis of 11,335 expressed sequence tags (ESTs) obtained as part of the Nematode EST project. RNA obtained from S. stercoralis L3i and L1 was co-hybridized to each array after labeling the individual samples with different fluorescent tags. Bioinformatic predictions of gene function were developed using a novel cDNA Annotation …

Rabies Virus Infection Induces Type I Interferon Production In An Ips-1 Dependent Manner While Dendritic Cell Activation Relies On Ifnar Signaling., Elizabeth J Faul, Celestine N Wanjalla, Mehul S Suthar, Michael Gale, Christoph Wirblich, Matthias J Schnell

Department of Microbiology and Immunology Faculty Papers

As with many viruses, rabies virus (RABV) infection induces type I interferon (IFN) production within the infected host cells. However, RABV has evolved mechanisms by which to inhibit IFN production in order to sustain infection. Here we show that RABV infection of dendritic cells (DC) induces potent type I IFN production and DC activation. Although DCs are infected by RABV, the viral replication is highly suppressed in DCs, rendering the infection non-productive. We exploited this finding in bone marrow derived DCs (BMDC) in order to differentiate which pattern recognition receptor(s) (PRR) is responsible for inducing type I IFN following infection …

Development Of A Mouse Monoclonal Antibody Cocktail For Post-Exposure Rabies Prophylaxis In Humans., Thomas Müller, Bernhard Dietzschold, Hildegund Ertl, Anthony R Fooks, Conrad Freuling, Christine Fehlner-Gardiner, Jeannette Kliemt, Francois X Meslin, Charles E Rupprecht, Noël Tordo, Alexander I Wanderler, Marie Paule Kieny

Department of Microbiology and Immunology Faculty Papers

As the demand for rabies post-exposure prophylaxis (PEP) treatments has increased exponentially in recent years, the limited supply of human and equine rabies immunoglobulin (HRIG and ERIG) has failed to provide the required passive immune component in PEP in countries where canine rabies is endemic. Replacement of HRIG and ERIG with a potentially cheaper and efficacious alternative biological for treatment of rabies in humans, therefore, remains a high priority. In this study, we set out to assess a mouse monoclonal antibody (MoMAb) cocktail with the ultimate goal to develop a product at the lowest possible cost that can be used …

Intracellular Bacteria Encode Inhibitory Snare-Like Proteins., Fabienne Paumet, Jordan Wesolowski, Alejandro Garcia-Diaz, Cedric Delevoye, Nathalie Aulner, Howard A Shuman, Agathe Subtil, James E Rothman

Department of Microbiology and Immunology Faculty Papers

Pathogens use diverse molecular machines to penetrate host cells and manipulate intracellular vesicular trafficking. Viruses employ glycoproteins, functionally and structurally similar to the SNARE proteins, to induce eukaryotic membrane fusion. Intracellular pathogens, on the other hand, need to block fusion of their infectious phagosomes with various endocytic compartments to escape from the degradative pathway. The molecular details concerning the mechanisms underlying this process are lacking. Using both an in vitro liposome fusion assay and a cellular assay, we showed that SNARE-like bacterial proteins block membrane fusion in eukaryotic cells by directly inhibiting SNARE-mediated membrane fusion. More specifically, we showed that …

A Critical Role For The Programmed Death Ligand 1 In Fetomaternal Tolerance, Indira Guleria, Arezou Khosroshahi, Mohammed Javeed Ansari, Antje Habicht, Miyuki Azuma, Hideo Yagita, Randolph J. Noelle

Dartmouth Scholarship

Fetal survival during gestation implies that tolerance mechanisms suppress the maternal immune response to paternally inherited alloantigens. Here we show that the inhibitory T cell costimulatory molecule, programmed death ligand 1 (PDL1), has an important role in conferring fetomaternal tolerance in an allogeneic pregnancy model. Blockade of PDL1 signaling during murine pregnancy resulted in increased rejection rates of allogeneic concepti but not syngeneic concepti. Fetal rejection was T cell

A Genetic Lesion That Arrests Plasma Cell Homing To The Bone Marrow, Loren D. Erickson, Ling-Li Lin, Biyan Duan, Laurence Morel, Randolph J. Noelle

Dartmouth Scholarship

The coordinated regulation of chemokine responsiveness plays a critical role in the development of humoral immunity. After antigen challenge and B cell activation, the emerging plasma cells (PCs) undergo CXCL12-induced chemotaxis to the bone marrow, where they produce Ab and persist. Here we show that PCs, but not B cells or T cells from lupus-prone NZM mice, are deficient in CXCL12-induced migration. PC unresponsiveness to CXCL12 results in a marked accumulation of PCs in the spleen of mice, and a concordant decrease in bone marrow PCs. Unlike normal mice, in NZM mice, a majority of the splenic PCs are long-lived. …

Evaluation Of A Tetracycline-Inducible Promoter In Staphylococcus Aureus In Vitro And In Vivo And Its Application In Demonstrating The Role Of Sigb In Microcolony Formation, B. T. Bateman, N. P. Donegan, T. M. Jarry, M. Palma

Dartmouth Scholarship

An inducible promoter system provides a powerful tool for studying the genetic basis for virulence. A variety of inducible systems have been used in other organisms, including pXyl-xylR-inducible promoter, the pSpac-lacI system, and the arabinose-inducible P_BAD promoter, but each of these systems has limitations in its application to Staphylococcus aureus. In this study, we demonstrated the efficacy of a tetracycline-inducible promoter system in inducing gene expression in S. aureus in vitro and inside epithelial cells as well as in an animal model of infection. Using the xyl/tetO promoter::gfp_uvr fusion carried on a shuttle …

Sart, A Repressor Of Α-Hemolysin In Staphylococcus Aureus, Katherine A. Schmidt, Adhar C. Manna, Steven Gill, Ambrose L. Cheung

Dartmouth Scholarship

In searching the Staphylococcus aureus genome, we found several homologs to SarA. One of these genes, sarT, codes for a basic protein with 118 residues and a predicted molecular size of 16,096 Da. Northern blot analysis revealed that the expression of sarT was repressed by sarA and agr. An insertion sarT mutant generated in S. aureus RN6390 and 8325-4 backgrounds revealed minimal effect on the expression of sarR and sarA. The RNAIII level was notably increased in the sarT mutant, particularly in postexponential-phase cells, while the augmentative effect on RNAII was less. SarT repressed the expression of alpha-hemolysin, as determined …