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Pathogens and Disease

Yang Zhang, Jun Yang, Guangchun Bai
Cyclic di-AMP (c-di-AMP) has been shown to play an important role in bacterial physiology and pathogen-host interactions. We previously reported that deletion of the sole c-di-AMP phosphodiesterase-encoding gene (cnpB) in Mycobacterium tuberculosis (Mtb) led to significant virulence attenuation. In this study, we found that ΔcnpB of M. bovis BCG (BCG) was unable to secrete c-di-AMP, which differs from Mtb ΔcnpB. We infected bone marrow-derived macrophages (BMDMs) with c-di-AMP-associated mutants generated from both Mtb and BCG...
January 31, 2018: Pathogens and Disease
Xiaogang Wang, Kevin Hybiske, Richard S Stephens
Chlamydia secrete into host cells a diverse array of effector proteins, but progress in characterizing the spatiotemporal localization of these proteins has been hindered by a paucity of genetic approaches in Chlamydia and also by the challenge of studying these proteins within the live cellular environment. We adapted a split-Green Fluorescent Protein (GFP) system for use in Chlamydia to label chlamydial effector proteins and track their localization in host cells under native environment. The efficacy of this system was demonstrated by detecting several known Chlamydia proteins including IncA, CT005, and CT694...
January 30, 2018: Pathogens and Disease
Jessica L Hastie, Phillip C Hanna, Paul E Carlson
Clostridium difficile (Cd) is the leading cause of antibiotic associated diarrhea. During an infection, Cd must compete with both the host and other commensal bacteria to acquire iron. Iron is essential for many cell processes, but it can also cause damage if allowed to form reactive hydroxyl radicals. In all organisms, levels of free iron are tightly regulated as are processes utilizing iron molecules. Genome wide transcriptional analysis of Cd grown in iron depleted conditions revealed significant changes in expression of genes involved in iron transport, metabolism and virulence...
January 30, 2018: Pathogens and Disease
Nicole Giordano, Jessica L Hastie, Paul E Carlson
Clostridium difficile (Cd) is an anaerobic, spore-forming bacterium capable of colonizing the gastrointestinal tract of humans. Colonization usually occurs following antibiotic induced disruption of the host microbiota, which also leads to an increase in oxygen within the gastrointestinal tract. We sought to understand how Cd responds to this microaerophilic condition that is likely experienced within the host. Transcriptome profiling showed differential regulation of genes involved in sugar metabolism, pyruvate metabolism, and stress responses...
January 30, 2018: Pathogens and Disease
John J Spencer, Rowan E Pitts, Rachel A Pearson, Lauren B King
Increasing multi-drug resistance (MDR) in Acinetobacter baumannii warrants therapeutic alternatives, and the bactericidal nature of antimicrobial peptides offers a possible approach. In this study, we examined the interaction of cathelicidin antimicrobial peptides (AMPs) WAM-1, a marsupial AMP, and LL-37, a human AMP, with A. baumannii clinical isolates. We characterized the antibiotic resistance of the isolates, the bacteriostatic and bactericidal effects of these AMPs, synergistic activity with antibiotics, and their effects on biofilm formation and dispersal...
January 23, 2018: Pathogens and Disease
German Torres, Christopher L Hoehmann, Joshua A Cuoco, Kyle Hitscherich, Charles Pavia, Michael Hadjiargyrou, Joerg R Leheste
Ketamine is one of several clinically important drugs whose therapeutic efficacy is due in part to their ability to act upon ion channels prevalent in nearly all biological systems. In studying eukaryotic and prokaryotic organisms in vitro, we show that ketamine short-circuits the growth and spatial expansion of three microorganisms, Stachybotrys chartarum, Staphylococcus epidermidis and Borrelia burgdorferi at doses efficient at reducing depression-like behaviors in mouse models of clinical depression. Although our findings do not reveal the mechanism(s) by which ketamine mediates its antifungal and antibacterial effects, we hypothesize that a function of L-glutamate signal transduction is associated with the ability of ketamine to limit pathogen expansion...
January 22, 2018: Pathogens and Disease
Liliana Scorzoni, Maria Pilar de Lucas, Junya de Lacorte Singulani, Haroldo Cesar de Oliveira, Patricia Akemi Assato, Ana Marisa Fusco-Almeida, Maria José Soares Mendes-Giannini
Paracoccidioidomycosis is a systemic fungal infection affecting mainly Latin American countries that is caused by Paracoccidioides brasiliensis and Paracoccidioides lutzii. During the study of fungal pathogenesis, in vivo studies are crucial to understand the overall mechanisms involving the infection as well as to search for new therapeutic treatments and diagnosis. Caenorhabditis elegans is described as an infection model for different fungi species and a well-characterized organism to study the innate immune response...
January 18, 2018: Pathogens and Disease
Flor Torres-Juarez, Lousseine Touqui, Juan Leon-Contreras, Cesar Rivas-Santiago, Jose A Enciso-Moreno, Rogelio Hernández-Pando, Bruno Rivas-Santiago
Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis (Mtb). Innate immunity is the first line of defense against Mtb and malfunctions in any of its components is associated with the susceptibility to the disease. Epithelial products, such as host defence peptides (HDP) are the first molecules produced to counteract the infection. Although a wide variety of HDP are produced by epithelial cells only few of them have been studied during Mtb infection. Here, we assessed the expression and production of the HDPs: psoriasin, sPLA2-IIA and RNase 7 in airway epithelial cells (NCI-H292), type II pneumocytes (A549 cells) and monocytes-derived macrophages from human peripheral blood mononuclear cells (bMDM) and from the human cell line THP1(MDM) after Mtb in vitro infection...
January 16, 2018: Pathogens and Disease
Patrícia M Alves, Eide Al-Badi, Cathryn Withycombe, Paul M Jones, Kevin J Purdy, Sarah E Maddocks
Debate regarding the co-existence of Staphylococcus aureus and Pseudomonas aeruginosa in wounds remains contentious, with the dominant hypothesis describing a situation akin to niche partitioning, whereby both microorganisms are present but occupy distinct regions of the wound without interacting. In contrast, we hypothesised that these microorganisms do interact during early co-colonisation in a manner beneficial to both bacteria. We assessed competitive interaction between S. aureus and P. aeruginosa in biofilm cultured for 24-72 h and bacterial aggregates analogous to those observed in early ( < 24h) biofilm formation, and interaction with human keratinocytes...
January 12, 2018: Pathogens and Disease
Prerana Sharma, Sanjukta Guha, Prashant Garg, Sanhita Roy
Pseudomonas aeruginosa is an opportunistic pathogen and is the major cause of corneal infection worldwide that secret several virulent toxins through its type III secretion system (T3SS). In defense against pathogenic insults, epithelial cells and macrophages express antimicrobial peptides (AMPs) that are essential components of host immune response. In this study, we have determined the expression of several AMPs in patients with P. aeruginosa corneal infection. We also used an in vitro model of infection using human corneal epithelial cells and macrophages to determine the gene expression of AMPs and cellular response to wild-type and T3SS mutant P...
January 9, 2018: Pathogens and Disease
Liliana Medina-Aparicio, Sonia Dávila, Javier E Rebollar-Flores, Edmundo Calva, Ismael Hernández-Lucas
In nature, microorganisms are constantly exposed to multiple viral infections and thus have developed many strategies to survive phage attack and invasion by foreign DNA. One of such strategies is the CRISPR-Cas bacterial immunological system. This defense mechanism is widespread in prokaryotes including several families such as Enterobacteriaceae. Much knowledge about the CRISPR-Cas system has been generated, including its biological functions, transcriptional regulation, distribution, utility as a molecular marker, and as a tool for specific genome editing...
January 9, 2018: Pathogens and Disease
Kenneth M Peterson, Patrick S Gellings
Vibrio cholerae is a gram-negative motile bacterium capable of causing fatal pandemic disease in humans via oral ingestion of contaminated water or food. Within the human intestine the motile vibrios must evade the innate host defense mechanisms, penetrate the mucus layer covering the small intestine, adhere to and multiply on the surface of the microvilli and cause disease via the action of cholera toxin. The explosive diarrhea associated with V. cholerae intestinal colonization leads to dissemination of the vibrios back into the environment to complete this phase of the life cycle...
January 5, 2018: Pathogens and Disease
Jaroslava Chupácová, Elisa Borghi, Giulia Morace, Agata Los, Helena Bujdáková
Candida albicans and Candida dubliniensis are related yeasts that differ in the expression of virulence-associated proteins involved in adherence and biofilm development. CR3-RP (complement receptor 3-related protein) is one of the surface antigens expressed by Candida species. The main objective of this research was to elucidate the effect of the polyclonal anti-CR3-RP antibody (Ab) on adherence and the biofilm formed by C. albicans SC5314 and C. dubliniensis CBS 7987 and 2 clinical isolates in vitro, ex vivo, and in vivo...
January 5, 2018: Pathogens and Disease
Adriana Freitas de Almeida, Elizabeth De Gaspari
Neisseria meningitidis bacterium is a gram-negative diplococcus. Among their serogroups, the B is one of the main causes of invasive meningococcal disease. Newborns and children are particularly susceptible to this infection because their immune systems that still maturing and relatively inexperienced. Thus, so further studies on the use of maternal immunization for protection against this disease are needed. The purpose of this study was to evaluate the potential immunogenic antigens from the outer membrane of N...
December 27, 2017: Pathogens and Disease
Mayuri Gogoi, Visweswaran Ravikumar, Narendra M Dixit, Dipshikha Chakravortty
CD4+T cell response is vital for successful clearance of Salmonella Typhimurium infection. Efficient antigen presentation is crucial for effective CD4+ T cell response. Previous study has reported that Salmonella abrogates antigen presentation capacity of dendritic cells in order to escape host adaptive immune response. In this study, we have elucidated the mechanism of Salmonella mediated downregulation of the total cellular MHC II pool in dendritic cells. Infected dendritic cells show upregulation of E3 ubiquitin ligase, MARCH1 expression, and K63 linked ubiquitination of MHC II...
December 26, 2017: Pathogens and Disease
Won Kyong Kim, Ja Young Moon, Jeong Sang Cho, Rashedunnabi Akanda, Byung Yong Park, Seong Kug Eo, Sang Youel Park, John Hwa Lee, Jin Hur
The aim of the present study is estimate the protective efficacy of B. abortus lysed cells by GI24 against brucellosis in Beagles. Group A were subcutaneously (sc) immunized with sterile PBS; and group B were sc immunized with approximately 3 × 109 of the lysed cells. Brucella-LPS-specific serum IgG titers and IL-4, TNF-α, and IFN-γ concentrations were investigated by ELISA. All dogs were intraconjunctivally challenged with B. abortus strain 544 at 6 weeks post prime immunization. The serum IgG titers were considerably higher in group B than in group A...
December 20, 2017: Pathogens and Disease
Tianyi Wu, Zhenjun Weng, Jia Xu, Gen Wen, Yaling Yu, Yimin Chai
Osteomyelitis is an inflammation of bone caused by invading organisms. TLR2, inflammatory cytokines, MAPK signaling pathway are involved in osteomyelitis. Baicalin, the major active constituent of the isolated root of Scutellaria lateriflora Georgi, has been shown to have anti-inflammatory effects. In this study, the potentials of baicalin against osteomyelitis were evaluated. We treated mice and MC3T3-E1 cells with baicalin together with Staphylococcus aureus infection, then analyzed the mice bone destruction, the expressions of TLR2 and osteogenic marker, the serum levels of pro-inflammatory factors and activation of MAPK signaling pathway...
December 13, 2017: Pathogens and Disease
Quézia Moura, Fernanda Esposito, Miriam R Fernandes, Maria Espinoza-Muñoz, Tiago A Souza, Silvia R Santos, Louise Cerdeira, Valéria Cassettari, Nilton Lincopan
The emergence of hypervirulent Klebsiella pneumoniae (hvKP) with multidrug-resistance (MDR) profile is a worrisome public health issue. We report the first draft genome sequence of a hypermucoviscous (positive string test) and MDR K. pneumoniae serotype K19, belonging to ST29, isolated from human infection. This strain harboured multiple antimicrobial resistance genes, including blaCTX-M-15, besides yersiniabactin and type 3 fimbriae virulence genes. In vivo experiments carried out with the Galleria mellonella infection model revealed that K...
December 6, 2017: Pathogens and Disease
Manyi Tan, Man Xu, Yongjian Xiao, Yafeng Xie, Chuanhao Jiang, Kang Zheng, Qian Chen, Feijun Zhao, Tiebing Zeng, Yimou Wu
Flagellin is a classical pathogen-associated molecular pattern that can evoke robust immune response. We have demonstrated previously that three full-length flagellins of Treponema pallidum, namely FlaB1, FlaB2 and FlaB3, did have diagnostic value in serodiagnosis of syphilis. Here, we selected and constructed three recombinant fragments of each complete FlaB, both the conserved N-terminal and the C-terminal region, and the middle variable part, with the goal of exploring fragment unique to Treponema pallidum for use as antigen target in a fragment based serological test...
December 5, 2017: Pathogens and Disease
Luisa Z Moreno, Frederico S Kremer, Lauren H Jaeger, Ana P Loureiro, Fabiana Miraglia, Marcos R Eslabao, Odir A Dellagostin, Walter Lilenbaum, Andrea M Moreno
The Leptospira interrogans serogroup Australis is traditionally described as pathogenic for swine although animals usually present low serologic response and mild clinical signs. The first isolation of a Leptospira interrogans serogroup Australis strain from swine, in Brazil, was recently described. Herein we present the genomic characterization of this strain (SU5) and further comparison with the Leptospira serovars reference genomes available in the GenBank database. The SU5 strain was characterized with sequence types previously described in a serogroup Australis isolated from human and presented a new ST98 that is thus far exclusively of the Brazilian porcine L...
November 25, 2017: Pathogens and Disease
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