Volume 4 Issue 3, March 2019

Molecular players involved in systemic and acute infections are relatively easy to pinpoint, whereas bacterial resilience during chronic infections remains less well understood. Pseudomonas aeruginosa encodes a quorum-regulated virulence factor, TesG, that promotes chronic lung infection by suppressing host inflammatory responses.

Klebsiella pneumoniae isolated from patients with primary sclerosing cholangitis was found to cause intestinal barrier dysfunction resulting in T-helper-17-cell-mediated hepatobiliary injury, providing evidence for specific gut-derived, pore-forming pathogens as triggers for immune-mediated liver disease.

Bacteria have previously been assumed to cope with environmental stress by tuning their total number of active ribosomes. Instead, a study in this issue of Nature Microbiology shows that from a heterogeneous pool of ribosomes, Vibrio vulnificus uses ribosomes with a particular ribosomal RNA variant to translate upregulated stress response mRNAs.

Severe fever with thrombocytopenia virus is an emerging, highly lethal tick-borne pathogen with growing impact. In this issue of Nature Microbiology, two papers make major progress towards a better understanding of its so far incompletely understood mechanisms of virulence.

Adaptive laboratory evolution experiments in Escherichia coli show that the pseudogene efeU can be repaired to restore the bacterium’s iron uptake system, demonstrating that pseudogenes may serve as an ‘adaptive repertoire’ of selectable traits.

Měnglà virus (MLAV) is a phylogenetically distinct bat filovirus, whose genome shares 32–54% nucleotide sequence identity with known filoviruses. MLAV glycoprotein-typed pseudo-types can transduce cell lines derived from humans, monkeys, dogs, hamsters and bats.

A bacterial strain that requires the neurotransmitter GABA for growth was identified and used to isolate GABA-producing bacteria, including Bacteroides spp., from human stool samples; the relative abundance of Bacteroides was negatively correlated with an altered GABA-mediated response in a depression patient cohort.

Genome sequencing of fractionated T-, B- and natural killer cells from patients with chronic active Epstein–Barr virus (EBV) infection sheds light on the nature of the EBV-infected progenitor and suggests a link between intragenic EBV deletions and EBV-associated neoplastic proliferations.

The structure of enterovirus 71 in complex with its receptor SCARB2 provides insights into the mechanism of viral uncoating within the endo/lysosome compartment and identifies few conserved key residues within the binding footprint that might facilitate the design of receptor mimic therapeutics.

During Toxoplasma gondii infection, diacylglycerol kinase 2 is secreted into the parasitophorous vacuole, leading to the production of phosphatidic acid, which is sensed by an atypical guanylate cyclase in the parasite plasma membrane, triggering egress from the host cell.

The non-structural protein NSs of the severe fever with thrombocytopenia syndrome virus interacts with ABIN2 and promotes formation and signalling of the TPL2–ABIN2–p105 kinase complex to induce expression of the immune-suppressive cytokine IL-10 and enhance viral pathogenesis.

An age-dependent immunocompetent ferret model for severe fever with thrombocytopenia syndrome phlebovirus (SFTSV) infection and pathogenesis recapitulates the clinical manifestations of human infections, including severe thrombocytopenia, reduced white blood cell counts and high fever with 93% mortality rate.

Antimicrobial peptide resistance genes are found to be widespread in the gut microbiome but are exchanged at lower rates compared to antibiotic resistance genes, with functional compatibility between bacteria being important for gene exchange.

A type I secretion effector, TesG, suppresses host immune response to promote chronic Pseudomonas aeruginosa infection.

Integration of longitudinal gut metagenomic datasets from children in Finland, Estonia and Russian Karelia reveals high strain-level diversity, which consequently impacts the functional capabilities of the early life microbiome.

By combining imaging and single-cell RNA sequencing, the authors identify genes regulated during cell growth and division and further analyse the heterogeneity of gene expression during adaptive and acute responses to changing environments.

Klebsiella pneumoniae from the gut microbiota of patients with primary sclerosing cholangitis (PSC) can damage the intestinal epithelial barrier, resulting in bacterial translocation and T helper 17 cell responses in the liver, indicating a role in PSC pathogenesis.

Heteroresistance in pathogenic bacterial clinical isolates is widespread and is mediated by unstable tandem amplification of resistance-associated genes.

In Vibrio vulnificus, ribosomes containing variable rRNAs encoded by the rrnI operon (I-ribosomes) preferentially translate a subset of mRNAs involved in bacterial adaptation of environmental changes, establishing divergent rRNAs as regulators of gene expression.

Combining the plaque assay with mass spectrometry imaging allowed high spatiotemporal resolution mapping of metabolites produced during viral infection of the alga Emiliania huxleyi, and revealed a shift in lipid metabolism towards odd-chain fatty acid lipids.