Search

The article focuses on a study which shows the involvement of the bioluminescent bacterium Vibrio fischeri in squid colonization.

The article focuses on a study which shows the need of copper for virulence of the fungus Cryptococcus neoformans.

The article focuses on a study which shows that the Vibrio cholerae two-component system CrbRS helps in regulating the consumption of acetate by this pathogen. Topics discussed include novel genes required for virulence, the gene encoding acetyl-CoA synthase and transcription of the gene encoding CrbS.

The article reports on a study showing that exposure to reactive oxygen species (ROS) in host macrophages results in a division of labour in Cryptococcus gattii populations. A non-replicative subpopulation of C. gattii emerges and facilitates the rapid growth of neighbouring fungal cells, thereby promoting the establishment of the infection. A new model for C. gattii pathogenesis which promotes replication of the proliferative population was provided.

The article reports on a study that examines 267,568 protein-coding genes from 134 archaeal genomes and compared them with their homologues from 1,847 reference bacterial genomes, wherein phylogenetic analysis of the genes suggested that they were acquired by archaea from bacteria.

The article reports on a study showing that the absence of antibiotics, Pseudomonas aeruginosa, rapidly loses small non-transmissible plasmid pNUK73, but the rate of decay in plasmid carriage slows down over time owing to the acquisition of mutations that lower the costs associated with carriage

The article presents the results of a study about the distribution and production of microbial products by biosynthetic gene clusters (BGCs). The researchers examined the antibacterial capacity of lactocillin and found that it was active against several pathogens such as Gardnerella vaginalis, Corynebacterium aurimucosum and Staphylococcus aureus. They also discovered the potential of microbial products, produced by BGCs, to mediate interactions between microbial community members.

The article discusses the study conducted by Donia et al. which focuses on the distribution of biosynthetic gene clusters (BGCs) for the thiopeptide class of antibiotics.

The article examines the connection of virulence and transmission of malaria parasite Plasmodium falciparum from asexually replicating parasites in human host. It states that the asexual parasites evade host immune responses through switching the expression of antigens of infected erythrocytes. It cites the key regulators for Plasmodium falciparum such as the proteins heterochromatin protein 1 (PfHP1) and histone deacetylase 2 (PfHda2).

The article discusses the concept of lipopolysaccharide (LPS) receptors via Toll-like receptor 4 (TLR4) wherein LPS has been shown to activate the non-canonical inflammasome in a TLR4. It examines the molecular partners of human caspase 4 and mouse caspase 11 for LPS recognition from Escherichia coli and from insect cells. It cites the role of caspases within the direct LPS binding results in caspase oligomerization and activation for the induction of pyroptosis.

The article discusses a study concerning the mechanism of transcriptional bursting in bacteria.

The article focuses on a study concerning the antagonism of the phosphatase PP1 by the measles virus V protein needed for innate immune escape of melanoma differentiation-associated protein 5 (MDA5). It mentions the key contributor to the pathogenicity of measles virus and its ability to suppress host immune responses. It explaines how measles virus avoids cytosolic detection by members of the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) family.

The article focuses on a study concerning agrobacterium tumefaciens which deploys a superfamily of type VI secretion DNase effectors as weapons for interbacterial competition in plant.

The article reports on a study concerning multisubstrate isotope labeling and metagenomic analysis of active soil bacterial communities.

The article presents a study conducted by researcher S. Mesnage which was focused on analyzing the use of LysM autolysin in identifying the peptidoglycan.

The article presents a study conducted by researcher M. Pop which was focused on analyzing the bacterias that causes diarrhoeal diseases in children of developing countries.

The article presents a study conducted by researcher H. Karttunen which was focused on analyzing that how DNA is damaged through the replication of the Herpes simplex virus 1 (HSV-1).

The article reports on the study which suggests that phages can actively interfere with translation of opal-recorded host genes.

The article reports on the result of a study regarding the pandemic potential of H10N8 from avian influenza viruses on human health.

The article reports on the study that describes the identification of a new peptide that prevents the formation and disruption of biofilms formed by several pathogens.

The article reports on the lactonohydrolase (LHC1), a Cryptococcus neoformans enzyme that introduces modifications in capsular structure to prevent fungal pathogens in the immune system.

Invariant natural killer T (iNKT) cells are activated during infection, but how they limit microbial growth is unknown in most cases. We investigated how iNKT cells suppress intracellular Mycobacterium tuberculosis (Mtb) replication. When co-cultured with infected macrophages, iNKT cell activation, as measured by CD25 upregulation and IFNγ production, was primarily driven by IL-12 and IL-18. In contrast, iNKT cell control of Mtb growth was CD1d-dependent, and did not require IL-12, IL-18, or IFNγ. This demonstrated that conventional activation markers did not correlate with iNKT cell effector function during Mtb infection. iNKT cell control of Mtb replication was also independent of TNF and cell-mediated cytotoxicity. By dissociating cytokine-driven activation and CD1d-restricted effector function, we uncovered a novel mediator of iNKT cell antimicrobial activity: GM-CSF. iNKT cells produced GM-CSF in vitro and in vivo in a CD1d-dependent manner during Mtb infection, and GM-CSF was both necessary and sufficient to control Mtb growth. Here, we have identified GM-CSF production as a novel iNKT cell antimicrobial effector function and uncovered a potential role for GM-CSF in T cell immunity against Mtb. [ABSTRACT FROM AUTHOR]

Vaccines that elicit T cell responses try to mimic protective memory T cell immunity after infection by increasing the frequency of Ag-specific T cells in the immune repertoire. However, the factors that determine immunodominance during infection and after vaccination and the relation between immunodominance and protection are incompletely understood. We previously identified TB10.4(20-28) as an immunodominant epitope recognized by H2-Kd-restricted CD8+ T cells after M. tuberculosis infection. Here we report a second epitope, EspA(150-158), that is recognized by a substantial number of pulmonary CD8+ T cells. The relative abundance of these T cells in the naive repertoire only partially predicts their relative frequency after M. tuberculosis infection. Furthermore, although vaccination with recombinant vaccinia virus expressing these epitopes changes their relative immunodominance in the preinfection T cell repertoire, this change is transient after challenge with M. tuberculosis. We speculate that factors intrinsic to the chronic nature of M. tuberculosis infection establishes the hierarchy of immunodominance and may explain the failure of some vaccines to provide protection. [ABSTRACT FROM AUTHOR]

The magnitude of antigen-specific CD8+T cell responses is not fixed but correlates with the severity of infection. Although by definition T cell response size is the product of both the capacity to recruit naïve T cells (clonal selection) and their subsequent proliferation (clonal expansion), it remains undefined how these two factors regulate antigen-specific T cell responses. We determined the relative contribution of recruitment and expansion by labeling naïve T cells with unique genetic tags and transferring them into mice. Under disparate infection conditions with different pathogens and doses, recruitment of antigen-specific T cells was near constant and close to complete. Thus, naïve T cell recruitment is highly efficient, and the magnitude of antigen-specific CD8+ T cell responses is primarily controlled by clonal expansion. [ABSTRACT FROM AUTHOR]

Anaemia is a frequent complication of chronic infectious diseases but the exact mechanisms by which it develops remain to be clarified. In the present work, we used a mouse model of mycobacterial infection to study molecular alterations of iron metabolism induced by infection. We show that four weeks after infection with Mycobacterium avium BALB/c mice exhibited a moderate anaemia, which was not accompanied by an increase on hepatic hepcidin mRNA expression. Instead, infected mice presented increased mRNA expression of ferroportin (Slc40a1), ceruloplasmin (Cp), hemopexin (Hpx), heme-oxygenase-1 (Hmox1) and lipocalin-2 (Lcn2). Both the anaemia and the mRNA expression changes of iron-related genes were largely absent in C.D2 mice which bear a functional allele of the Nramp1 gene. Data presented in this work suggest that anaemia due to a chronic mycobacterial infection may develop in the absence of elevated hepcidin expression, is influenced by Nramp1 and may involve lipocalin-2., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Eicosanoids regulate whether human and murine macrophages infected with Mycobacterium tuberculosis die by apoptosis or necrosis. The death modality is important since apoptosis is associated with diminished pathogen viability and should be viewed as a form of innate immunity. Apoptotic vesicles derived from infected macrophages are also an important source of bacterial antigens that can be acquired by dendritic cells to prime antigen-specific T cells. This review integrates in vitro and in vivo data on how apoptosis of infected macrophages is linked to development of T cell immunity against M. tuberculosis., (Copyright © 2011 Institut Pasteur. Published by Elsevier SAS. All rights reserved.)

The ability of the thymus to generate a population of T cells that is, for the most part, self-restricted and self-tolerant depends to a great extent on the Ags encountered during differentiation. We recently showed that mycobacteria disseminate to the thymus, which raised the questions of how mycobacteria within the thymus influence T cell differentiation and whether such an effect impacts host-pathogen interactions. Athymic nude mice were reconstituted with thymic grafts from Mycobacterium avium-infected or control noninfected donors. T cells generated from thymi of infected donors seemed generally normal, because they retained the ability to reconstitute the periphery and to respond to unspecific stimuli in vitro as well as to antigenic stimulation with third-party Ags, such as OVA, upon in vivo immunization. However, these cells were unable to mount a protective immune response against a challenge with M. avium. The observation that thymic infection interferes with T cell differentiation, generating T cells that are tolerant to pathogen-specific Ags, is of relevance to understand the immune response during chronic persistent infections. In addition, it has potential implications for the repertoire of T cells generated in patients with a mycobacterial infection recovering from severe lymphopenia, such as patients coinfected with HIV and receiving antiretroviral therapy.

The magnitude of antigen-specific CD8+ T cell responses is not fixed but correlates with the severity of infection. Although by definition T cell response size is the product of both the capacity to recruit naïve T cells (clonal selection) and their subsequent proliferation (clonal expansion), it remains undefined how these two factors regulate antigen-specific T cell responses. We determined the relative contribution of recruitment and expansion by labeling naïve T cells with unique genetic tags and transferring them into mice. Under disparate infection conditions with different pathogens and doses, recruitment of antigen-specific T cells was near constant and close to complete. Thus, naïve T cell recruitment is highly efficient, and the magnitude of antigen-specific CD8+ T cell responses is primarily controlled by clonal expansion.