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Infection and Immunity

Xiaojun Zhong, Yue Zhang, Yinchu Zhu, Wenyang Dong, Jiale Ma, Zihao Pan, Shipra Roy, Chengping Lu, Huochun Yao
Streptococcus suis has received increasing attention for its involvement in severe human infections worldwide, as well as in multidrug resistance. Two-component signaling systems (TCSSs) play important roles in bacterial adaptation to various environmental stimuli. In this study, we identified a novel TCSS encoded in S. suis serotype 2 (SS2), designated as VraSRSS , which is involved in bacterial pathogenicity and susceptibility to antimicrobials. Our data demonstrated that the yvqFSS gene located upstream of vraSRSS shared the same promoter with the TCSS genes, which was directly regulated by VraSRSS as showed in electrophoretic mobility shift assays...
April 23, 2018: Infection and Immunity
Joanna K Chorazeczewski, Maya Aleshnick, Victoria Majam, Winter A Okoth, Regina Kurapova, Adovi Akue, Mark KuKuruga, Sanjai Kumar, Miranda S Oakley
Recent studies have demonstrated that a subpopulation of neutrophils express the TCRαβ combinatorial immunoreceptor in humans and mice. Here, we report that a Plasmodium berghei ANKA murine malaria infection induces expansion of TCRβ expressing CD11b+ Ly6G+ neutrophils in the spleen during the early phase of infection. Measurement of TCRβ transcript and protein levels of neutrophils in wildtype versus nude and Rag1 KO mice establishes that the observed expression is not a consequence of nonspecific antibody staining or passive receptor expression due to phagocytosis or trogocytosis of peripheral T cells...
April 23, 2018: Infection and Immunity
John C Freedman, Mauricio A Navarro, Eleonora Morrell, Juliann Beingesser, Archana Shrestha, Bruce A McClane, Francisco A Uzal
Clostridium perfringens enterotoxin (CPE) is responsible for the gastrointestinal symptoms of C. perfringens type A food poisoning and some cases of non-foodborne gastrointestinal diseases such as antibiotic-associated diarrhea. In the presence of certain predisposing medical conditions, this toxin can also be absorbed from the intestines to cause enterotoxemic death. CPE action in vivo involves intestinal damage, which begins at the villus tips. The cause of this CPE-induced intestinal damage is unknown but CPE can induce a caspase-3 mediated apoptosis in cultured enterocyte-like Caco-2 cells...
April 23, 2018: Infection and Immunity
Liwen Deng, Rong Mu, Thomas A Weston, Brady L Spencer, Roxanne Liles, Kelly S Doran
Streptococcus agalactiae (Group B Streptococcus , GBS) is often a commensal bacterium that colonizes healthy adults asymptomatically and is a frequent inhabitant of the vaginal tract in women. However, in immune-compromised individuals, particularly the newborn, GBS may transition to an invasive pathogen and cause serious disease. Despite currently recommended intrapartum antibiotic prophylaxis for GBS-positive mothers, GBS remains a leading cause of neonatal septicemia and meningitis. To adapt to the various host environments encountered during its disease cycle, GBS possesses multiple two-component regulatory systems (TCS)...
April 23, 2018: Infection and Immunity
Joshua L Mieher, Matthew R Larson, Norbert Schormann, Sangeetha Purushotham, Ren Wu, Kanagalaghatta R Rajashankar, Hui Wu, Champion Deivanayagam
The high-resolution structure of Glucan binding protein C (GbpC) at 1.14 Å, a sucrose-dependent virulence factor of the dental caries pathogen Streptococcus mutans , has been determined. GbpC not only shares structural similarities with the V-regions of AgI/II and SspB, but also functional adherence to SAG and its scavenger receptor cysteine rich domains (SRCRs) which is not only a newly identified function for GbpC, but also an additional fail-safe binding mechanism for S. mutans Despite the structural similarities with S...
April 23, 2018: Infection and Immunity
Trever C Smith, Sarah M Helm, Yue Chen, Ying-Han Lin, S L Rajasekhar Karna, J Seshu
Borrelia burgdorferi ( Bb ), the agent of Lyme disease (LD), uses host-derived signals to modulate gene expression during the vector and mammalian phases of infection. Microarray analysis of mutants lacking <u>B</u>orrelia host-<u>ad</u>aptation <u>R</u>egulator (BadR) revealed down-regulation of genes encoding enzymes whose role in the patho-physiology of Bb is unknown. Immunoblot analysis of the badR mutants confirmed reduced levels of these enzymes and one of these enzymes encoded by bb0086 , shares homology to prokaryotic magnesium chelatase and Lon-type proteases...
April 23, 2018: Infection and Immunity
Mayuka Fujimoto, Ryosuke Goto, Takeshi Haneda, Nobuhiko Okada, Tsuyoshi Miki
Salmonella enterica , a common cause of diarrhea, has to colonize the gut lumen to elicit the disease. In the gut, the pathogen encounters a vast array of environmental stresses that cause perturbations in the bacterial envelope. The CpxRA two-component system monitors envelope perturbations and responds by altering the bacteria gene expression profile. This allows Salmonella to survive under such harmful conditions. Therefore, CpxRA activation is likely to contribute to Salmonella gut infection. However, the role of CpxRA-mediated envelope stress response in Salmonella -induced diarrhea is unclear...
April 23, 2018: Infection and Immunity
Natalia Castaño-Rodríguez, Alexander P Underwood, Juan Merif, Stephen M Riordan, William D Rawlinson, Hazel M Mitchell, Nadeem O Kaakoush
The morbidity and mortality resulting from acute gastroenteritis and associated chronic sequelae represent a substantial burden on health care systems worldwide. Few studies have investigated changes in the gut microbiome following an episode of acute gastroenteritis. Using non-directed 16S rRNA gene amplicon sequencing, the faecal microbiota of 475 patients with acute gastroenteritis was examined. Patient age was correlated to the overall microbial composition, with a decrease in Faecalibacterium observed in older patients...
April 23, 2018: Infection and Immunity
Eduardo R Cobo, Ravi Holani, France Moreau, Kiminori Nakamura, Tokiyoshi Ayabe, Jennifer R Mastroianni, Andre Ouellette, Kris Chadee
Enteric α-defensins, termed cryptdins (Crps) in mice, and lysozymes secreted by Paneth cells contribute to innate host defense in the ileum. Antimicrobial factors including lysozymes and β-defensins are often embedded in luminal glycosylated colonic Muc2 mucin secreted by goblet cells that form the protective mucus layer critical in gut homeostasis and pathogen invasion. In this study we investigated ileal innate immunity against Entamoeba histolytica (Eh ), the causative agent of intestinal amebiasis, by inoculating parasites in closed ileal loops in Muc2+/+ and Muc2-/- littermates and quantifying Paneth cell localization (lysozyme expression) and function (Crps secretion)...
April 23, 2018: Infection and Immunity
Adeline Barthelemy, Valentin Sencio, Daphnée Soulard, Lucie Deruyter, Christelle Faveeuw, Ronan Le Goffic, François Trottein
Severe bacterial (pneumococcal) infections are commonly associated with influenza and are significant contributors to the excess morbidity and mortality of influenza. Disruption of lung tissue integrity during influenza participates in bacterial pulmonary colonization and dissemination out of the lungs. Interleukin (IL)-22 has gained considerable interest in anti-inflammatory and anti-infection immunotherapy over the last decade. In the current study, we investigated the effect of exogenous IL-22 delivery on the outcome of pneumococcal superinfection post-influenza...
April 16, 2018: Infection and Immunity
Sandra G Morrison, Amanda M Giebel, Evelyn C Toh, Horace J Spencer, David E Nelson, Richard P Morrison
Some members of the genus Chlamydia , including the human pathogen Chlamydia trachomatis , infect multiple tissues including the genital and gastrointestinal (GI) tracts. However, it is unknown if bacterial targeting to these sites is mediated by multifunctional or distinct chlamydial factors. We previously showed that disruption of individual large clostridial toxin homologs encoded within the Chlamydia muridarum plasticity zone were not critical for murine genital tract infection. Here, we assessed if cytotoxin genes contribute to C...
April 16, 2018: Infection and Immunity
Alex Wong, Margaret A Grau, Anirudh K Singh, Shireen A Woodiga, Samantha J King
Streptococcus gordonii is an early colonizer of the oral cavity. Although a variety of S. gordonii adherence mechanisms have been described, current dogma is that the major receptor for S. gordonii is sialic acid. However, as many bacterial species in the oral cavity produce neuraminidase that can cleave terminal sialic acid, it is unclear whether S. gordonii relies on sialic acid for adherence to oral surfaces or if this species has developed alternative binding strategies. Previous studies have examined adherence to immobilized glycoconjugates and identified binding to additional glycans; but no prior studies have defined the contribution of these different glycan structures in adherence to oral epithelial cells...
April 16, 2018: Infection and Immunity
D T Bolick, P H Q S Medeiros, S E Ledwaba, A A M Lima, J P Nataro, E M Barry, R L Guerrant
Enterotoxigenic E. coli are major causes of traveler's diarrhea as well as endemic diarrhea and stunting in children in developing areas. However a small mammal model has been badly needed to better understand and assess mechanisms, vaccines and interventions. We report a murine model of ETEC diarrhea, weight loss and enteropathy, and investigate the role of zinc on the outcomes. LT+ST producing enterotoxigenic E. coli (ETEC) given to weaned C57BL/6 mice after antibiotic disruption of normal microbiota cause growth impairment, watery diarrhea, heavy stool shedding and mild to moderate intestinal inflammation, the latter worse with zinc deficiency...
April 16, 2018: Infection and Immunity
Kelsey J Yamada, Cortney E Heim, Amy L Aldrich, Casey M Gries, Anna G Staudacher, Tammy Kielian
S. aureus is a leading cause of device-associated biofilm infections, which represent a serious health care concern based on their chronicity and antibiotic resistance. We previously reported that S. aureus biofilms preferentially recruit myeloid-derived suppressor cells (MDSCs), which promote monocyte and macrophage anti-inflammatory properties. This is associated with increased myeloid arginase-1 (Arg-1) expression, which has been linked to anti-inflammatory and pro-fibrotic activity that are observed during S...
April 16, 2018: Infection and Immunity
Elena Stylianou, Rachel Harrington-Kandt, Julia Beglov, Naomi Bull, Nawamin Pinpathomrat, Gwendolyn M Swarbrick, Deborah A Lewinsohn, David M Lewinsohn, Helen McShane
The development of a vaccine against tuberculosis (TB), a disease caused by Mycobacterium tuberculosis ( M.tb ), is urgently needed. The only currently available vaccine, BCG, has variable efficacy. One approach in the global vaccine development effort is focused on boosting BCG using subunit vaccines. The identification of novel antigens for inclusion in subunit vaccines is a critical step in the TB vaccine development pathway. We selected four novel mycobacterial antigens recognised during the course of human infection...
April 16, 2018: Infection and Immunity
Taylor B Poston, Catherine M O'Connell, Jenna Girardi, Jeanne E Sullivan, Uma M Nagarajan, Anthony Marinov, Amy M Scurlock, Toni Darville
CD4 T cells and antibody are required for optimal acquired immunity to C. muridarum genital tract infection, and T cell-mediated IFNγ production is necessary to clear infection in the absence of humoral immunity. However, the role of T cell-independent immune responses during primary infection remains unclear. We investigated this question by inoculating wild-type and immune-deficient mice with C. muridarum CM001, a clonal isolate capable of enhanced extragenital replication. Genital inoculation of wild-type mice resulted in transient dissemination to the lungs and spleen that then was rapidly cleared from these organs...
April 16, 2018: Infection and Immunity
Laurence Quemeneur, Nadine Petiot, Nadège Arnaud-Barbe, Catherine Hessler, Patricia J Freda Pietrobon, Patricia Londoño-Hayes
Clostridium difficile infection (CDI) is a leading cause of nosocomial and antibiotic-associated diarrhea. A vaccine, based on formalin-inactivated toxins A and B purified from anaerobic cultures of C. difficile strain VPI 10463 (toxinotype 0), has been in development for the prevention of symptomatic CDI. We evaluated the breadth of protection conferred by this C. difficile toxoid vaccine in cross-neutralization assessments using sera from vaccinated hamsters against a collection of 165 clinical isolates. Hamsters antisera raised against the C...
April 9, 2018: Infection and Immunity
Ingar Olsen, Frank C Nichols
The keystone periodontal pathogen Porphyromonas gingivalis produces phosphorylated dihydroceramide lipids (sphingolipids) such as phosphoethanolamine dihydroceramide (PE DHC) and phosphoglycerol dihydroceramide (PG DHC) lipids. Phosphorylated DHCs (PDHCs) from P. gingivalis can affect a number of mammalian cellular functions such as potentiation of prostaglandin secretion from gingival fibroblasts, promotion of RANKL-induced osteoclastogenesis, promotion of apoptosis and enhancement of autoimmunity. In P. gingivalis, these lipids affect anchoring of surface polysaccharides, resistance to oxidative stress and presentation of surface polysaccharides (anionic polysaccharides and K-antigen capsule)...
April 9, 2018: Infection and Immunity
Tianjun Xu, Qing Chu, Junxia Cui, Ruixuan Huo
Inflammation is the host self-protection mechanism to eliminate pathogens invasion. The excessive inflammatory response could result in uncontrolled inflammation, autoimmune diseases or pathogen dissemination. Recent studies have widely shown that microRNAs contribute to the regulation of inflammation in mammals by repressing gene expression at the posttranscriptional level. However, the miRNA-mediated mechanism in inflammatory response remains hazy for fish. In the present study, the regulatory mechanism of miR-216a-mediated inflammatory response has been well addressed in teleost fish...
April 9, 2018: Infection and Immunity
Kadar Moideen, Nathella Pavan Kumar, Dina Nair, Vaithilingam V Banurekha, Ramalingam Bethunaickan, Subash Babu
Granulocytes are activated during tuberculosis (TB) infection and act as immune effector cells and granulocyte responses are implicated in TB pathogenesis. Plasma levels of neutrophil and eosinophil granular proteins provide an indirect measure of degranulation. In this study, we wanted to examine the levels of neutrophil and eosinophil granular proteins in individuals with pulmonary tuberculosis (PTB) and to compare them with the levels in latent TB (LTB) individuals. Hence, we measured the plasma levels of myeloperoxidase (MPO), neutrophil elastase, and proteinase-3; major basic protein (MBP), eosinophil derived neurotoxin (EDN), eosinophil cationic protein (ECP) and eosinophil peroxidase (EPX) in these individuals...
April 9, 2018: Infection and Immunity
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