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https://www.readbyqxmd.com/read/28928215/influenza-virus-hemagglutinin-stalk-specific-antibodies-in-human-serum-are-a-surrogate-marker-for-in-vivo-protection-in-a-serum-transfer-mouse-challenge-model
#1
Henning Jacobsen, Madhusudan Rajendran, Angela Choi, Haakon Sjursen, Karl A Brokstad, Rebecca J Cox, Peter Palese, Florian Krammer, Raffael Nachbagauer
The immunogenicity of current influenza virus vaccines is assessed by measuring an increase of influenza virus-specific antibodies in a hemagglutination inhibition assay. This method exclusively measures antibodies against the hemagglutinin head domain. While this domain is immunodominant, it has been shown that hemagglutination inhibition titers do not always accurately predict protection from disease. In addition, several novel influenza virus vaccines that are currently under development do not target the hemagglutinin head domain, but rather more conserved sites, including the hemagglutinin stalk...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928214/fishing-out-the-hidden-enemy-advances-in-detecting-and-measuring-latent-hiv-infected-cells
#2
Vinayaka R Prasad, Ganjam V Kalpana
The indomitable aspect of HIV-1 infection is not that HIV-1 proviral DNA is integrated into host DNA but that it can also turn itself off, remaining invisible to drug or immune surveillance. Thus, the goals of eradication include ways to precisely excise HIV-1 DNA or wake up the silent HIV-1 provirus and eliminate the infected cells thus identified. Methods to identify and fish out the latently infected cells or to delineate their characteristics are being rapidly developed. In 2016, Baxter et al. (A. E. Baxter, J...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928213/cell-cycle-inhibition-to-treat-sleeping-sickness
#3
Conrad L Epting, Brian T Emmer, Nga Y Du, Joann M Taylor, Ming Y Makanji, Cheryl L Olson, David M Engman
African trypanosomiasis is caused by infection with the protozoan parasite Trypanosoma brucei During infection, this pathogen divides rapidly to high density in the bloodstream of its mammalian host in a manner similar to that of leukemia. Like all eukaryotes, T. brucei has a cell cycle involving the de novo synthesis of DNA regulated by ribonucleotide reductase (RNR), which catalyzes the conversion of ribonucleotides into their deoxy form. As an essential enzyme for the cell cycle, RNR is a common target for cancer chemotherapy...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928212/population-and-whole-genome-sequence-based-characterization-of-invasive-group-a-streptococci-recovered-in-the-united-states-during-2015
#4
Sopio Chochua, Ben J Metcalf, Zhongya Li, Joy Rivers, Saundra Mathis, Delois Jackson, Robert E Gertz, Velusamy Srinivasan, Ruth Lynfield, Chris Van Beneden, Lesley McGee, Bernard Beall
Group A streptococci (GAS) are genetically diverse. Determination of strain features can reveal associations with disease and resistance and assist in vaccine formulation. We employed whole-genome sequence (WGS)-based characterization of 1,454 invasive GAS isolates recovered in 2015 by Active Bacterial Core Surveillance and performed conventional antimicrobial susceptibility testing. Predictions were made for genotype, GAS carbohydrate, antimicrobial resistance, surface proteins (M family, fibronectin binding, T, R28), secreted virulence proteins (Sda1, Sic, exotoxins), hyaluronate capsule, and an upregulated nga operon (encodes NADase and streptolysin O) promoter (Pnga3)...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928211/the-crispr-spacer-space-is-dominated-by-sequences-from-species-specific-mobilomes
#5
Sergey A Shmakov, Vassilii Sitnik, Kira S Makarova, Yuri I Wolf, Konstantin V Severinov, Eugene V Koonin
Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein (CRISPR-Cas) systems store the memory of past encounters with foreign DNA in unique spacers that are inserted between direct repeats in CRISPR arrays. For only a small fraction of the spacers, homologous sequences, called protospacers, are detectable in viral, plasmid, and microbial genomes. The rest of the spacers remain the CRISPR "dark matter." We performed a comprehensive analysis of the spacers from all CRISPR-cas loci identified in bacterial and archaeal genomes, and we found that, depending on the CRISPR-Cas subtype and the prokaryotic phylum, protospacers were detectable for 1% to about 19% of the spacers (~7% global average)...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928210/analysis-of-individuals-from-a-dengue-endemic-region-helps-define-the-footprint-and-repertoire-of-antibodies-targeting-dengue-virus-3-type-specific-epitopes
#6
Daniela V Andrade, Leah C Katzelnick, Doug G Widman, Angel Balmaseda, Aravinda M de Silva, Ralph S Baric, Eva Harris
The four dengue virus serotypes (DENV1 to 4) cause dengue, a major public health problem worldwide. Individuals exposed to primary DENV infections develop serotype-specific neutralizing antibodies, including strongly neutralizing antibodies targeting quaternary epitopes. To date, no studies have measured the levels and kinetics of serum antibodies directed to such epitopes among populations in regions where dengue is endemic. Here, we use a recombinant DENV4 (rDENV4/3-M14) displaying a major DENV3 type-specific quaternary epitope recognized by human monoclonal antibody 5J7 to measure the proportion, magnitude, and kinetics of DENV3 type-specific neutralizing antibody responses targeting this epitope...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928209/combining-comprehensive-analysis-of-off-site-lambda-phage-integration-with-a-crispr-based-means-of-characterizing-downstream-physiology
#7
Yu Tanouchi, Markus W Covert
During its lysogenic life cycle, the phage genome is integrated into the host chromosome by site-specific recombination. In this report, we analyze lambda phage integration into noncanonical sites using next-generation sequencing and show that it generates significant genetic diversity by targeting over 300 unique sites in the host Escherichia coli genome. Moreover, these integration events can have important phenotypic consequences for the host, including changes in cell motility and increased antibiotic resistance...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928208/picornaviruses-and-apoptosis-subversion-of-cell-death
#8
REVIEW
Sarah N Croft, Erin J Walker, Reena Ghildyal
Infected cells can undergo apoptosis as a protective response to viral infection, thereby limiting viral infection. As viruses require a viable cell for replication, the death of the cell limits cellular functions that are required for virus replication and propagation. Picornaviruses are single-stranded RNA viruses that modify the host cell apoptotic response, probably in order to promote viral replication, largely as a function of the viral proteases 2A, 3C, and 3CD. These proteases are essential for viral polyprotein processing and also cleave cellular proteins...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928207/a-perfect-storm-increased-colonization-and-failure-of-vaccination-leads-to-severe-secondary-bacterial-infection-in-influenza-virus-infected-obese-mice
#9
Erik A Karlsson, Victoria A Meliopoulos, Nicholas C van de Velde, Lee-Ann van de Velde, Beth Mann, Geli Gao, Jason Rosch, Elaine Tuomanen, Jon McCullers, Peter Vogel, Stacey Schultz-Cherry
Obesity is a risk factor for developing severe disease following influenza virus infection; however, the comorbidity of obesity and secondary bacterial infection, a serious complication of influenza virus infections, is unknown. To fill this gap in knowledge, lean and obese C57BL/6 mice were infected with a nonlethal dose of influenza virus followed by a nonlethal dose of Streptococcus pneumoniae Strikingly, not only did significantly enhanced death occur in obese coinfected mice compared to lean controls, but also high mortality was seen irrespective of influenza virus strain, bacterial strain, or timing of coinfection...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928206/microbial-metabolic-networks-at-the-mucus-layer-lead-to-diet-independent-butyrate-and-vitamin-b12-production-by-intestinal-symbionts
#10
Clara Belzer, Loo Wee Chia, Steven Aalvink, Bhawani Chamlagain, Vieno Piironen, Jan Knol, Willem M de Vos
Akkermansia muciniphila has evolved to specialize in the degradation and utilization of host mucus, which it may use as the sole source of carbon and nitrogen. Mucus degradation and fermentation by A. muciniphila are known to result in the liberation of oligosaccharides and subsequent production of acetate, which becomes directly available to microorganisms in the vicinity of the intestinal mucosa. Coculturing experiments of Amuciniphila with non-mucus-degrading butyrate-producing bacteria Anaerostipes caccae, Eubacterium hallii, and Faecalibacterium prausnitzii resulted in syntrophic growth and production of butyrate...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28928205/bola-is-required-for-the-accurate-regulation-of-c-di-gmp-a-central-player-in-biofilm-formation
#11
Ricardo N Moreira, Clémentine Dressaire, Susana Barahona, Lisete Galego, Volkhard Kaever, Urs Jenal, Cecília M Arraiano
The bacterial second messenger cyclic dimeric GMP (c-di-GMP) is a nearly ubiquitous intracellular signaling molecule involved in the transition from the motile to the sessile/biofilm state in bacteria. C-di-GMP regulates various cellular processes, including biofilm formation, motility, and virulence. BolA is a transcription factor that promotes survival in different stresses and is also involved in biofilm formation. Both BolA and c-di-GMP participate in the regulation of motility mechanisms leading to similar phenotypes...
September 19, 2017: MBio
https://www.readbyqxmd.com/read/28900027/sirtuin-lipoamidase-activity-is-conserved-in-bacteria-as-a-regulator-of-metabolic-enzyme-complexes
#12
Elizabeth A Rowland, Todd M Greco, Caroline K Snowden, Anne L McCabe, Thomas J Silhavy, Ileana M Cristea
Lipoic acid is an essential metabolic cofactor added as a posttranslational modification on several multimeric enzyme complexes. These protein complexes, evolutionarily conserved from bacteria to humans, are core regulators of cellular metabolism. While the multistep enzymatic process of adding lipoyl modifications has been well characterized in Escherichia coli, the enzyme required for the removal of these lipoyl moieties (i.e., a lipoamidase or delipoylase) has not yet been identified. Here, we describe our discovery of sirtuins as lipoamidases in bacteria and establish their conserved substrates...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900026/activity-related-conformational-changes-in-d-d-carboxypeptidases-revealed-by-in-vivo-periplasmic-f%C3%A3-rster-resonance-energy-transfer-assay-in-escherichia-coli
#13
Nils Y Meiresonne, René van der Ploeg, Mark A Hink, Tanneke den Blaauwen
One of the mechanisms of β-lactam antibiotic resistance requires the activity of d,d-carboxypeptidases (d,d-CPases) involved in peptidoglycan (PG) synthesis, making them putative targets for new antibiotic development. The activity of PG-synthesizing enzymes is often correlated with their association with other proteins. The PG layer is maintained in the periplasm between the two membranes of the Gram-negative cell envelope. Because no methods existed to detect in vivo interactions in this compartment, we have developed and validated a Förster resonance energy transfer assay...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900025/psp-stress-response-proteins-form-a-complex-with-mislocalized-secretins-in-the-yersinia-enterocolitica-cytoplasmic-membrane
#14
Disha Srivastava, Amal Moumene, Josué Flores-Kim, Andrew J Darwin
The bacterial phage shock protein system (Psp) is a conserved extracytoplasmic stress response that is essential for the virulence of some pathogens, including Yersinia enterocolitica It is induced by events that can compromise inner membrane (IM) integrity, including the mislocalization of outer membrane pore-forming proteins called secretins. In the absence of the Psp system, secretin mislocalization permeabilizes the IM and causes rapid cell death. The Psp proteins PspB and PspC form an integral IM complex with two independent roles...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900024/metabolic-roles-of-uncultivated-bacterioplankton-lineages-in-the-northern-gulf-of-mexico-dead-zone
#15
J Cameron Thrash, Kiley W Seitz, Brett J Baker, Ben Temperton, Lauren E Gillies, Nancy N Rabalais, Bernard Henrissat, Olivia U Mason
Marine regions that have seasonal to long-term low dissolved oxygen (DO) concentrations, sometimes called "dead zones," are increasing in number and severity around the globe with deleterious effects on ecology and economics. One of the largest of these coastal dead zones occurs on the continental shelf of the northern Gulf of Mexico (nGOM), which results from eutrophication-enhanced bacterioplankton respiration and strong seasonal stratification. Previous research in this dead zone revealed the presence of multiple cosmopolitan bacterioplankton lineages that have eluded cultivation, and thus their metabolic roles in this ecosystem remain unknown...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900023/gene-expression-in-leishmania-is-regulated-predominantly-by-gene-dosage
#16
Stefano A Iantorno, Caroline Durrant, Asis Khan, Mandy J Sanders, Stephen M Beverley, Wesley C Warren, Matthew Berriman, David L Sacks, James A Cotton, Michael E Grigg
Leishmania tropica, a unicellular eukaryotic parasite present in North and East Africa, the Middle East, and the Indian subcontinent, has been linked to large outbreaks of cutaneous leishmaniasis in displaced populations in Iraq, Jordan, and Syria. Here, we report the genome sequence of this pathogen and 7,863 identified protein-coding genes, and we show that the majority of clinical isolates possess high levels of allelic diversity, genetic admixture, heterozygosity, and extensive aneuploidy. By utilizing paired genome-wide high-throughput DNA sequencing (DNA-seq) with RNA-seq, we found that gene dosage, at the level of individual genes or chromosomal "somy" (a general term covering disomy, trisomy, tetrasomy, etc...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900022/binding-of-nad-glycohydrolase-to-streptolysin-o-stabilizes-both-toxins-and-promotes-virulence-of-group-a-streptococcus
#17
Jorge J Velarde, Maghnus O'Seaghdha, Buket Baddal, Benedicte Bastiat-Sempe, Michael R Wessels
The globally dominant, invasive M1T1 strain of group A Streptococcus (GAS) harbors polymorphisms in the promoter region of an operon that contains the genes encoding streptolysin O (SLO) and NAD(+)-glycohydrolase (NADase), resulting in high-level expression of these toxins. While both toxins have been shown experimentally to contribute to pathogenesis, many GAS isolates lack detectable NADase activity. DNA sequencing of such strains has revealed that reduced or absent enzymatic activity can be associated with a variety of point mutations in nga, the gene encoding NADase; a commonly observed polymorphism associated with near-complete abrogation of activity is a substitution of aspartic acid for glycine at position 330 (G330D)...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900021/another-brick-in-the-wall-a-rhamnan-polysaccharide-trapped-inside-peptidoglycan-of-lactococcus-lactis
#18
Irina Sadovskaya, Evgeny Vinogradov, Pascal Courtin, Julija Armalyte, Mickael Meyrand, Efstathios Giaouris, Simon Palussière, Sylviane Furlan, Christine Péchoux, Stuart Ainsworth, Jennifer Mahony, Douwe van Sinderen, Saulius Kulakauskas, Yann Guérardel, Marie-Pierre Chapot-Chartier
Polysaccharides are ubiquitous components of the Gram-positive bacterial cell wall. In Lactococcus lactis, a polysaccharide pellicle (PSP) forms a layer at the cell surface. The PSP structure varies among lactococcal strains; in L. lactis MG1363, the PSP is composed of repeating hexasaccharide phosphate units. Here, we report the presence of an additional neutral polysaccharide in L. lactis MG1363 that is a rhamnan composed of α-l-Rha trisaccharide repeating units. This rhamnan is still present in mutants devoid of the PSP, indicating that its synthesis can occur independently of PSP synthesis...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900020/petrobactin-is-exported-from-bacillus-anthracis-by-the-rnd-type-exporter-apex
#19
A K Hagan, A Tripathi, D Berger, D H Sherman, P C Hanna
Bacillus anthracis-a Gram-positive, spore-forming bacterium-causes anthrax, a highly lethal disease with high bacteremia titers. Such rapid growth requires ample access to nutrients, including iron. However, access to this critical metal is heavily restricted in mammals, which requires B. anthracis to employ petrobactin, an iron-scavenging small molecule known as a siderophore. Petrobactin biosynthesis is mediated by asb gene products, and import of the iron-bound (holo)-siderophore into the bacterium has been well studied...
September 12, 2017: MBio
https://www.readbyqxmd.com/read/28900019/the-human-salivary-microbiome-is-shaped-by-shared-environment-rather-than-genetics-evidence-from-a-large-family-of-closely-related-individuals
#20
Liam Shaw, Andre L R Ribeiro, Adam P Levine, Nikolas Pontikos, Francois Balloux, Anthony W Segal, Adam P Roberts, Andrew M Smith
The human microbiome is affected by multiple factors, including the environment and host genetics. In this study, we analyzed the salivary microbiomes of an extended family of Ashkenazi Jewish individuals living in several cities and investigated associations with both shared household and host genetic similarities. We found that environmental effects dominated over genetic effects. While there was weak evidence of geographical structuring at the level of cities, we observed a large and significant effect of shared household on microbiome composition, supporting the role of the immediate shared environment in dictating the presence or absence of taxa...
September 12, 2017: MBio
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