Extending the therapeutic window for acute viral infections could save lives. Here, the authors show that combination treatment with a human monoclonal antibody and remdesivir initiated at 6 days post infection with Marburg virus provides 80% protection in non-human primates.
Microbiology and infectious diseases
The study of microorganisms, the most abundant living entities on Earth, aims to understand their unique biology and the influence they have on human health, disease, and life in general. Here, we highlight work that furthers our understanding of the microbial world.
Glycoprotein US9 of human cytomegalovirus downregulates the activating immune ligand MICA*008 to avoid NK cell activation. Here, Seidel et al. show that the signal peptide of US9 is cleaved unusually slowly, causing MICA*008 to be retained in the endoplasmic reticulum (ER) and degraded via the ER quality control system.
Prokaryotic cell transcriptomics has been limited to mixed or sub-population dynamics and individual cells within heterogeneous populations. Here the authors develop a ‘TRANSITomic’ approach to profile transcriptomes of single Burkholderia pseudomallei cells as they transit through host cell infection.
Origin of rebound virus in chronically SIV-infected Rhesus monkeys following treatment discontinuation
The origin and nature of rebound HIV-1 virus following antiretroviral therapy (ART) discontinuation still remains unclear. Here, Liu et al. suggest that intact proviral DNA in peripheral blood and lymph node mononuclear cells during ART suppression likely is the source of viral rebound following ART discontinuation.
SARS-CoV and SARS-CoV-2 are transmitted through the air between ferrets over more than one meter distance
Some epidemiological data suggests that SARS-CoV-2 can be transmitted through the air over longer distances. Here, Kutter et al. show in the ferret model that SARS-CoV-2 and SARS-CoV can be transmitted through the air over more than a meter distance, however, data should be interpreted with care, as ferrets are likely more susceptible to coronavirus infections.
HBV covalently closed circular DNA (cccDNA) enables and persists in chronic infection, but the molecular mechanism of its formation is unclear. Here, Wei and Ploss elucidate the detailed kinetics and biochemical steps by which the relaxed circular DNA is converted into cccDNA.
It is unknown whether capsulized fecal microbiota transplantation (FMT) can modify the microbiota of people with HIV. Here, the authors report the results of a pilot double-blind study, where 30 HIV-infected subjects on ART were randomized to either weekly oral FMT capsules or placebo for 8 weeks, and show that transplanted microbiota successfully engrafts and is able to attenuate HIV-associated dysbiosis.
Analysis of metagenome-assembled viral genomes from the human gut reveals diverse putative CrAss-like phages with unique genomic features
Here, the authors analyze 4907 Circular Metagenome Assembled Genomes from human microbiomes and identify and characterize nearly 600 diverse genomes of crAss-like phages, finding two putative families with unusual genomic features, including high density of self-splicing introns and inteins.
Transcription factor Rme1 regulates meiosis and pseudohyphal growth in baker’s yeast, but its role in the meiosis-defective pathogen Candida albicans is unclear. Here, Hernández-Cervantes et al. show that Rme1 activates the expression of genes required for formation of asexual spores in Candida species.
Tuberculosis necrotizing toxin (TNT) is secreted by Mycobacterium tuberculosis to kill host cells. Here, Tak, Dokland and Niederweis show that proteins EsxE and EsxF form membrane-spanning hetero-oligomeric pores that are important for TNT secretion.
Discovery of multiple anti-CRISPRs highlights anti-defense gene clustering in mobile genetic elements
Mobile genetic elements have evolved anti-CRISPR (Acr) proteins to bypass the immunity provided by prokaryotic CRISPR–Cas systems. Here, the authors identify 11 type I Acrs encoded on mobile genetic elements, and show that acr loci neighborhoods can be used to discover inhibitors of other bacterial defense systems.
The circadian factors BMAL1/CLOCK and REV-ERB are master regulators of the human liver transcriptome but their role in hepatitis B virus infection is largely unknown. Here, Zhuang et al. show that REV-ERB regulates hepatitis B virus entry and BMAL1 directly binds HBV DNA and activates viral genome transcription.
Systematic functional analysis of Leishmania protein kinases identifies regulators of differentiation or survival
Protein kinases are fundamental in cellular signalling required for Leishmania survival throughout the life cycle. Here, Baker and Catta-Preta et al. report on a kinome-wide functional study in Leishmania mexicana to define protein kinases with roles in life cycle transition.
The fungus Neurospora crassa is a model organism for the study of various biological processes, but it is not known to be infected by any viruses. Here, Honda et al. identify RNA viruses that infect N. crassa and examine viral replication and RNAi-mediated antiviral responses, thus establishing this fungus as a model for the study of host-virus interactions.
The small molecule AI-2 acts as a quorum sensing signal, mediating communication within and between many bacterial species. Here, the authors identify a new type of AI-2 receptor, consisting of a dCACHE domain that is present in many bacterial and archaeal proteins.
Increased power from conditional bacterial genome-wide association identifies macrolide resistance mutations in Neisseria gonorrhoeae
The mechanisms underlying resistance of Neisseria gonorrhoeae to the antibiotic azithromycin are incompletely understood. Here, Ma et al. conduct a conditional genome-wide association study to identify new resistance mutations and experimentally confirm that a mutation in ribosomal protein L4 confers increased resistance.
Plasmodium falciparum secretes extracellular vesicles (EVs) while growing inside red blood cells (RBCs). Here the authors show that these EVs contain assembled and functional 20S proteasome complexes that remodel the cytoskeleton of naïve human RBCs, priming the RBCs for parasite invasion.
Non-human primates are important animal models for studying SARS-CoV-2 infection. Here, Salguero et al. directly compare rhesus and cynomolgus macaques and show that both species represent COVID-19 disease of mild clinical cases, and provide a lung histopathology scoring system.
Exploring beyond clinical routine SARS-CoV-2 serology using MultiCoV-Ab to evaluate endemic coronavirus cross-reactivity
Serology is an important way to monitor SARS-CoV-2 infection in the population and support vaccine development. Here the authors develop a multiplex immunoassay including spike and nucleocapsid proteins of SARS-CoV-2 and the endemic human coronaviruses with high specificity and sensitivity.
In this single-arm clinical trial, the authors show that treatment of COVID-19 patients with bevacizumab, an anti-vascular endothelial growth factor drug, can improve PaO2/FiO2 ratios and oxygen-support status. Relative to an external control group, bevacizumab shows clinical efficacy by improving oxygenation.
Exposure to pesticides in utero impacts the fetal immune system and response to vaccination in infancy
Control of mosquito populations using pesticides is important for malaria elimination, but effects of pesticides on humans aren’t well understood. Here, Prahl et al. show in a cohort of pregnant Ugandan women and their infants that household spraying with bendiocarb affects the fetal immune system and response to vaccination in infancy.
Remdesivir is under evaluation for treatment of COVID-19 in clinical trials. Here, the authors report results of remdesivir treatment in a patient with COVID-19 and the genetic antibody deficiency XLA. They show a temporally correlated clinical and virological response, suggesting that remdesivir can reduce SARS-CoV-2 replication in patients.
Gastrointestinal microbiota composition predicts peripheral inflammatory state during treatment of human tuberculosis
Antibiotic therapy can lead to pathogen clearance, but also to alterations in the gut microbiota and systemic immune responses. Here, the authors analyze data from patients with tuberculosis and healthy subjects to show that pathogen clearance and gut microbiota alterations are independently associated with antibiotic-induced changes of the inflammatory response of active tuberculosis.
The nucleotide pGpp acts as a third alarmone in Bacillus, with functions distinct from those of (p) ppGpp
Nucleotides pppGpp and ppGpp regulate bacterial responses to nutritional and other stresses, while the potential roles of the related pGpp are unclear. Here, Yang et al. systematically identify proteins interacting with these nucleotides in Bacillus, and show that pGpp has roles distinct from those of (p)ppGpp.
Infections with bacteria of the genus Sarcina are associated with gastric diseases of unclear etiology. Here, Owens et al. show that infection with a distinct Sarcina species is strongly associated with a lethal disease that affects sanctuary chimpanzees in Sierra Leone.
Isolation of a member of the candidate phylum ‘Atribacteria’ reveals a unique cell membrane structure
A key feature that differentiates prokaryotic cells from eukaryotes is the absence of an intracellular membrane surrounding the chromosomal DNA. Here, the authors isolate a member of the ubiquitous, yet-to-be-cultivated bacterial phylum ‘Candidatus Atribacteria’ that has an intracytoplasmic membrane apparently surrounding the nucleoid.
Here, Hanke et al. immunize an alpaca with SARS-CoV-2 spike protein domains and identify a nanobody that binds the receptor binding domain of spike in both the up and down conformations and sterically hinders ACE2 engagement.
Single-cell atlas of the first intra-mammalian developmental stage of the human parasite Schistosoma mansoni
Schistosomes undergo several develepmental stages during infection of humans. Here, the authors perform single-cell RNA sequencing on the earliest intra-mammalian stage of Schistosoma mansoni and generate a comprehensive cell-type atlas for this human parasite.
Neonatal antibiotic exposure impairs child growth during the first six years of life by perturbing intestinal microbial colonization
In this study, Omry Koren, Samuli Rautava and colleagues report a sex-specific association between neonatal antibiotic exposure and weight and height gain during the first six years of life and showing that boys but not girls exposed to neonatal antibiotics exhibit impaired weight and height development.
Clostridioides difficile exploits toxin-mediated inflammation to alter the host nutritional landscape and exclude competitors from the gut microbiota
The effects of antibiotics on the gut microbiota can lead to enhanced colonization of Clostridioides difficile (C. difficile) and toxin-mediated pathogenesis. Here, using defined toxin-mutant strains and a murine model, the authors provide insights into how toxin-induced inflammation alters C. difficile metabolism, host tissue gene expression and gut microbiota, together influencing a beneficial niche for infection.
Virus speciation cannot be fully explained by the evolution of different host specificities. Here, Chaikeeratisak et al. identify ways viruses can remain genetically isolated despite co-infecting the same cell, providing insight into how new virus species evolve.
Artemisinin-resistant K13 mutations rewire Plasmodium falciparum’s intra-erythrocytic metabolic program to enhance survival
The emergence and spread of artemisinin resistance has compromised antimalarial efficacy. Here, Mok et al. apply quantitative transcriptomics, proteomics, and metabolomics to provide evidence that K13 mutations alter multiple aspects of the parasite’s intra-erythrocytic development to enhance survival following artemisinin treatment.
Viruses have been difficult to position in the Tree of Life using phylogenetic methods. This study uses an ancient enzyme multi-subunit RNA polymerase (RNAP) to reveal a novel viral group, the Caudovirales, and to suggest an ancient origin of RNAP in this group.
Game theory has contributed much to the understanding of social evolution. In an elegant combination of experimental tests and modelling, this study suggests that when bacteria face intense competition, repeated retaliation outcompetes a single tit-for-tat response to attack.
A study of the first genomes of the marine Hikarchaeia, the closest known relatives of Haloarchaea, is presented. Their inclusion in ancestral reconstructions unveils an intermediate stage in the evolutionary transition from ancestral anaerobic methanogens to modern day aerobic halophiles.
The evolutionary relationships within Archaea remain unresolved. Here, the authors used genomic approaches to study the Undinarchaeota, a previously uncharacterized clade of DPANN, shed light on their position in an updated archaeal phylogeny and illuminate the history of archaeal genome evolution.
Ammonia-oxidising archaea of the phylum Thaumarchaeota are important organisms in the nitrogen cycle. Using 12 new genomes, this study finds evidence that Nitrososphaerales evolution was marked by lateral gene transfer followed by gene duplication.
Controlled human infection models (CHIMs) provide a pathway for accelerating vaccine development. Here, the authors describe the isolation, characterization, and GMP manufacture of a clinical Leishmania major strain to be used as a resource for CHIM studies of sand fly transmitted cutaneous leishmaniasis.
Herpes simplex virus establishes lifelong latency in ganglionic neurons, which are the source for recurrent infection. Here Aubert et al. report a promising antiviral therapy based on gene editing with adeno-associated virus-delivered meganucleases, which leads to a significant reduction in ganglionic HSV loads and HSV reactivation.
Bacterial nanotubes and other similar membranous structures have been reported to function as conduits between cells to exchange DNA, proteins, and nutrients. Here the authors provide evidence that bacterial nanotubes are formed only by dead or dying cells, thus questioning their previously proposed functions.
Fungi produce oxygenated fatty acids, or oxylipins, of unclear function. Here, Niu et al. show that an Aspergillus oxylipin induces various developmental processes in several fungi, including lateral branching in human pathogenic Aspergillus species, and appressorium formation in the plant pathogen Magnaporthe grisea.
Yellow fever is absent from the Asia/Pacific region, despite presence of the mosquito vector. Here, the authors demonstrate that mosquitoes collected from field sites across the region are capable of transmitting yellow fever virus, indicating that vector competence is not a barrier to disease spread.
Genome sequencing can be used to infer pathogen transmission dynamics and inform public health responses. Here, the authors sequence >1,200 SARS-CoV-2 samples from Victoria, Australia and find genomic support for the effectiveness of social restrictions in reducing transmission.
Analysis of immune, microbiota and metabolome maturation in infants in a clinical trial of Lactobacillus paracasei CBA L74-fermented formula
Milk breastfeeding and prebiotic-supplemented formulas have varying effects on the infant gut microbiome. Here, in a randomized controlled clinical trial, the authors investigate the effects of a Lactobacillus paracasei-fermented formula on the immune defense mechanisms, microbiota and its metabolome in full term infants.
Hormonal contraception alters vaginal microbiota and cytokines in South African adolescents in a randomized trial
Hormonal contraception may alter women’s susceptibility to HIV. Here, the authors report the results of a randomized clinical trial substudy assessing the effects of injectable Net-En, oral contraceptives (COC) and Nuvaring on vaginal microbiota and cytokines, associating COC with lower microbial diversity and Nuvaring with increased inflammation.
An adenovirus-vectored COVID-19 vaccine confers protection from SARS-COV-2 challenge in rhesus macaques
A vaccine protecting from SARS-CoV-2 infection is needed. Here the authors generate a replication-incompetent adenovirus based vaccine expressing SARS-CoV-2 spike, show protection from infection in non-human primates, and analyze the immune response after intramuscular and intranasal vaccination.
Malaria parasites regulate intra-erythrocytic development duration via serpentine receptor 10 to coordinate with host rhythms
The mechanism underlying periodicity of Plasmodium’s intra-erythrocytic developmental cycle (IDC) is unclear. Here, Subudhi et al. show that serpentine receptor 10 (SR10) plays a role in regulating the schedule of the IDC in line with the timing of host daily rhythms.