eLife: latest articles by subject

In vitro sexual dimorphism establishment in schistosomes

Matt.Berriman@glasgow.ac.uk (Benjamin J Hulme) — Thu, 10 Sep 2026 00:00:00 +0000

Schistosomes are parasitic flatworms that cause Schistosomiasis, a major neglected tropical disease that affects more than 250 million people worldwide. With two distinct sexes, a heterogametic female (ZW) and a homogametic male (ZZ), schistosomes are an exception among flatworms, which are largely hermaphroditic. Sexual dimorphism in schistosomes only becomes apparent by adulthood within the mammalian host. However, the cellular and molecular mechanisms underlying the sexual differentiation of are poorly understood, partly due to intrinsic challenges in assessing parasite development in vivo. Therefore, robust and reproducible approaches for maintaining and developing parasites in vitro are needed to overcome these difficulties. To date, few studies have focused on protocols that allow cultured parasites to reach sexual dimorphic stages, and none have been reproduced, limiting the ability to understand the sexual biology of this major human parasite. Here, we refine a protocol for long-term culture of newly transformed cercariae that developed in vitro into sexually dimorphic forms. We assessed the effect of adding two different sera, foetal bovine serium (FBS) and human serum (HS), to culture medium supplemented with red blood cells. In contrast to FBS-culture parasites, those grown in HS digested red blood cells, a crucial step for long term parasite development. Furthermore, sexual dimorphism was clearly established in the HS-cultured parasites, albeit delayed, in contrast to most FBS-cultured parasites that did not progress beyond an early liver stage. Moreover, in EdU-pulse experiments, cells within HS-cultured parasites continuously proliferated, but markedly fewer proliferated in FBS-culture. By enabling reproducible parasite develoment in vitro, this protocol creates new opportunities for dissecting mechanisms that underly sexual dimorphim, as well as for screening in vitro for new interventions across the life cycle of these major human parasites.

The C3–C3aR axis modulates trained immunity in alveolar macrophages

alexander.earhart@wustl.edu (Aasritha Nallapu) — Thu, 10 Sep 2026 00:00:00 +0000

Complement protein C3 is crucial for immune responses in mucosal sites such as the lung, where it aids in microbe elimination, and enhances inflammation. While trained immunity – enhanced secondary responses of innate immune cells after prior exposure – is well-studied, the role of the complement system in trained immune responses remains unclear. We investigated the role of C3 in trained immunity and found that alveolar macrophage (AM) C3 and C3aR1 expression increased in humans after an intranasal exposure to a training stimulus. In vivo, trained wild-type mice showed significantly elevated proinflammatory cytokines and increased C3a levels upon a second stimulus. Ex vivo, trained C3-deficient AMs displayed reduced chemokine and cytokine output as well as impaired phagocytosis and reactive oxygen species production compared to wild-type AMs. Real-time confocal microscopy of live, intact mouse alveoli revealed that AMs internalize C3 rapidly after alveolar microinstillation, as compared to C3a. Correspondingly, the blunted cytokine output was restored by exogenous C3 but not by C3a. Inhibiting C3aR, both pharmacologically and with a genetic C3aR knockout, prevented this restoration, indicating the necessity of C3aR engagement. Mechanistically, trained WT AMs demonstrated enhanced glycolytic activity compared to C3-deficient AMs – a defect corrected by exogenous C3 in a C3aR-dependent manner. These findings reveal that C3 modulates trained immunity in AMs through C3aR signaling and highlight a novel role for C3 in trained immunity.

Ribosomal RNA methylation by GidB modulates discrimination of mischarged tRNA

jfraser@fraserlab.com (Babak Javid) — Fri, 04 Sep 2026 00:00:00 +0000

Despite redundant cellular pathways to minimize translational errors, errors in protein synthesis are common. Pathways and mechanisms to minimize errors are classified as pre-ribosomal or ribosomal. Pre-ribosomal pathways are primarily concerned with the appropriate charging of tRNAs with their cognate amino acids. By contrast, the ribosomal decoding center is considered ‘blind’ to mischarged tRNAs since these have cognate codon•anti-codon pairing. Here, we identified that in mycobacteria, deletion of the 16S ribosomal RNA methyltransferase gidB led to increased ribosomal discrimination of mischarged tRNAs. Discrimination only occurred in mycobacteria enriched from environments or genetic backgrounds with high rates of mistranslation. GidB deletion was necessary, but not sufficient for reducing mistranslation due to misacylation. Analysis of new cryo-EM structures of the M. smegmatis ribosomes derived from wild-type and gidB-deleted strains point to the interaction between the base methylated by GidB on the 16S RNA and an asparagine on the ribosomal S12 protein that, when mistranslated to aspartate, may be involved in altering translational fidelity. Our data suggest a mechanism by which mycobacterial ribosomes can discriminate mischarged tRNAs and that 16S rRNA differential methylation by GidB may act to prevent catastrophic translational error.

Membrane affinity difference between MinD monomer and dimer is not crucial for MinD gradient formation in Bacillus subtilis

h.strahl@ncl.ac.uk (Davide Marenduzzo) — Wed, 02 Sep 2026 00:00:00 +0000

Proteins can diffuse micrometers in seconds, yet bacterial cells are able to maintain stable protein gradients. The best-studied bacterial protein gradient is the Min system of Escherichia coli. In rod-shaped bacteria, the MinCD proteins prevent formation of minicells by inhibiting FtsZ polymerization close to the cell poles. In E. coli, these proteins oscillate between cell poles within a minute, resulting in an increased MinCD concentration at the poles. This oscillation is caused by the interaction between MinD and the protein MinE, which form an ATP-driven reaction-diffusion system, whereby the ATPase MinD cycles between a monomeric cytosolic and a dimeric membrane-attached state. Bacillus subtilis also has MinCD, but lacks MinE. In this case, MinCD forms a static gradient that requires the transmembrane protein MinJ, located at cell poles and cell division sites. A recent reaction-diffusion model was successful in recreating the MinD gradient in B. subtilis, assuming that MinD cycles between cytosol and membrane, like in E. coli. Here, we show that the monomeric and dimeric states of B. subtilis MinD have comparable membrane affinities, that MinD interacts with MinJ as a dimer, and that MinJ is not required for membrane localization of MinD. Based on these new findings, we tested different models, using kinetic Monte Carlo simulations, and found that a difference in diffusion rate between the monomer and dimer, rather than a difference in membrane affinity, is important for B. subtilis MinCD gradient formation.

Three metabolic pathways replenishing the one-carbon pool collectively support growth and virulence of Listeria monocytogenes

sascha.kahlfuss@med.ovgu.de (Dunja Bruder) — Wed, 19 Aug 2026 00:00:00 +0000

The bacterium Listeria monocytogenes can grow in the cytoplasm of infected human cells, but there it relies on specific biosynthetic pathways for intracellular nutrient supply. We previously found that the glycine cleavage system (GCS) is needed for intracellular growth. The GCS decarboxylates glycine for generation of 1C-tetrahydrofolates (1C-THF), folate-dependent one-carbon donors needed for biosynthesis of other metabolites. We continued our studies on the GCS and showed that a L. monocytogenes ΔgcvPAB mutant, lacking the GCS glycine dehydrogenase, is attenuated without resembling the phenotype of classical virulence factor mutants. The ΔgcvPAB mutant also grew poorly in synthetic medium, explained by the presence of glycine that was toxic for this strain. Selection of glycine-resistant suppressors yielded a survivor, in which the N- and C-terminal parts of the formate-tetrahydrofolate ligase (fhs) gene, which is naturally separated into two parts by a premature stop codon in the L. monocytogenes reference strain EGD-e were reassembled into a full-length open-reading frame. Like the GCS, Fhs also feeds the 1C-THF pool, and its restoration cured the virulence defects of the ΔgcvPAB mutant. Another suppressor had a mutated glyA gene, encoding serine hydroxymethyltransferase, and combinatorial deletions of gcvPAB and glyA in fhs⁻ and fhs⁺ backgrounds demonstrated a role of GlyA in 1C-THF metabolism. Our results show that three pathways feed the 1C-THF pool to support growth and virulence of L. monocytogenes and represent the first example of the spontaneous reactivation of an L. monocytogenes gene that is inactivated by a premature stop codon.

Replicative slender bloodstream forms complete transmission of Trypanosoma brucei without prior differentiation into stumpy forms

markus.engstler@biozentrum.uni-wuerzburg.de (Anna Sophie Kreis) — Wed, 19 Aug 2026 00:00:00 +0000

We have previously shown that the slender form of Trypanosoma (T.) brucei is able to infect teneral tsetse flies, develop to the first fly form, which is the procyclic form, and complete the life cycle in the insect vector (Schuster et al., 2021). Further, analysis of the transmission index (TI; defined as the number of salivary gland infections relative to the number of midgut infections) revealed a higher TI for slender as compared to stumpy forms under laboratory conditions, which included the addition of N-acetylglucosamine (NAG) to the infective bloodmeal. Here, we show that slender trypanosomes can establish infections in both male and female tsetse flies and in both teneral and non-teneral flies without requiring supplements in the bloodmeal. Additionally, an RNA sequencing time course was performed on both slender and stumpy cells during their transition into procyclic forms. This analysis revealed that slender- and stumpy-form trypanosomes remain transcriptionally distinct throughout differentiation into the procyclic form. Furthermore, while the protein associated with differentiation 1 (PAD1) remains essential for the transition, slender cells do not require expression of other hallmark stumpy-form traits, such as cell-cycle arrest or the shortening of their flagella or microtubule corset. Instead, slender trypanosomes are able to transition directly into procyclic forms. Taken together, these findings demonstrate that slender cells of T. brucei can follow a distinct transcriptional trajectory towards the procyclic form and can establish infections in teneral and non-teneral tsetse flies, thereby contributing to the transmission and spread of these African parasites.

Five-layer systems analysis of Leishmania stage differentiation reveals an essential role for protein degradation in parasite development

pascale.pescher@pasteur.fr (Anne Boland) — Wed, 12 Aug 2026 00:00:00 +0000

Vector-borne, protist parasites have evolved complex developmental programs to adapt to very distinct host environments. How these important pathogens transition between insect and mammalian stages is only poorly understood. Here, we investigated stage differentiation in Leishmania donovani, a trypanosomatid parasite with constitutive gene transcription, offering a model to study post-transcriptional regulation. Using a five-layer integrative systems analysis (genome to metabolome), we compared hamster-derived amastigotes and culture-derived promastigotes. Genomic adaptation was excluded as a major driver of differentiation, while differential mRNA turnover emerged as a key mechanism of stage-specific gene expression. Transcriptomic and proteomic comparisons revealed a broad dynamic range of protein abundance changes that correlated poorly with mRNA levels. This discrepancy was linked to (i) altered snoRNA expression and rRNA modifications, indicating stage-specific tuning of translation, and (ii) differential protein degradation, supported by proteomics following proteasome inhibition with lactacystin. Lactacystin impaired amastigote-to-promastigote differentiation, highlighting the importance of proteasomal activity. Overall, our analysis links Leishmania development to coordinated post-transcriptional regulatory networks. Our findings provide a powerful new resource for research programs that aim to dissect the emergent properties of regulatory networks and feedback loops underlying Leishmania stage differentiation, serving as a blueprint for other vector-borne pathogens that rely on disease-associated developmental transitions.

A dual role for PGLYRP1 in host defense and immune regulation during B. pertussis infection

cskerry@som.umaryland.edu (Ciaran Skerry) — Tue, 11 Aug 2026 00:00:00 +0000

Bordetella pertussis, the etiologic agent of whooping cough, remains a serious public health concern despite widespread vaccination. Improved therapeutics and vaccines are urgently needed. Host recognition of bacterial peptidoglycan (PGN), including B. pertussis extracellular PGN fragment tracheal cytotoxin (TCT) shapes the immune response to infection. Peptidoglycan recognition proteins (PGLYRPs) are a conserved innate immune family that bind bacterial PGN and are primarily known for bactericidal activity in mammals; however, their immune modulatory roles are beginning to gain appreciation. The role of PGLYRPs in mammalian host defenses to Gram-negative pathogens, such as B. pertussis, remains largely unknown. Here, using knockout mice, single-cell and bulk transcriptomics, and functional assays, we identify a dual role for PGLYRP1 in modulating host immune responses to B. pertussis. PGLYRP1 contributes to antibacterial responses and paradoxically dampens inflammatory responses and inhibits bacterial killing later in infection. Mechanistically, PGLYRP1 enhances NOD1 signaling in response to TCT while suppressing NOD2− and triggering receptor expressed on myeloid cells-1 (TREM-1)-mediated inflammatory pathways. TCT-bound PGLYRP1 selectively impairs TREM-1 activation compared to PGNs from other bacteria. These findings demonstrate that B. pertussis co-opts PGLYRP1 to alter immune signaling, revealing a novel immune evasion mechanism with implications for vaccine design and host-directed therapeutics.

Nanoscopy reveals heparan sulfate clusters as docking sites for SARS-CoV-2 attachment and entry

jyewdell@nih.gov (Albert J Jin) — Thu, 06 Aug 2026 00:00:00 +0000

Virus entry is thought to involve binding a unique receptor for cell attachment and cytosolic entry. For SARS-CoV-2 underlying the COVID-19 pandemic, angiotensin-converting enzyme 2 (ACE2) is widely considered the receptor for cell-surface attachment and subsequent cell entry. Using advanced light microscopy to resolve individual virions and receptors, we found instead that heparan sulfate (HS), not ACE2, mediates SARS-CoV-2 cell-surface attachment, and subsequent endocytosis. ACE2 functions only downstream of HS to enable viral genome expression. Instead of binding single HS molecules that electrostatically interact with viral surface proteins weakly, SARS-CoV-2 binds clusters of ~6–137 HS molecules projecting 60–410 nm above the plasma membrane. These tall, HS-rich clusters, present at about one per 6 μm², act as docking sites for viral attachment. Blocking HS binding with the clinically used HS-binding agent pixantrone strongly inhibited an authentic pathogen, the SARS-CoV-2 Omicron JN.1 subvariant, from attaching to and infecting human airway cells. This work establishes a revised entry paradigm in which HS clusters mediate SARS-CoV-2 attachment and endocytosis, with ACE2 acting downstream, thereby identifying HS interactions as a key anti-COVID-19 strategy. This paradigm and its therapeutic implications may apply broadly beyond COVID-19 because, analogous to SARS-CoV-2, HS binds many other viruses but is only considered an attachment regulator.

Pathogen-phage geomapping to overcome resistance

camilla.do@bcm.edu (Anthony W Maresso) — Thu, 06 Aug 2026 00:00:00 +0000

The rise of antibiotic resistance has renewed interest in bacteriophages as therapeutic alternatives. However, coevolution of phage and bacteria will naturally give rise to phage-resistant pathogens, complicating phage therapy efforts. A critical bottleneck in the production of phage therapeutics is the discovery of virulent phages against resistant pathogens. Conventional methods for discovery are time-consuming, biased, and laborious, limiting the potential for identifying suitable phage candidates. To overcome these limitations, we combined small-volume environmental sampling with 16 S rRNA sequencing to identify reservoirs where bacterial hosts co-exist with their phage predators. This strategy, which we term geographical phage mapping (geΦmapping), pinpoints ecological ‘hotspots’ for targeted phage hunting. We further developed a portable phage hunting device (ΦHD) that generates highly enriched phage concentrates directly from these reservoirs. By integrating geΦmapping with high-throughput enrichment, we constructed the RΦ library, a diverse collection of novel phages. We captured and isolated 36 new phages targeting extremely resistant organisms across various ESKAPE pathogens when conventional phage hunting and experimental evolution approaches failed.

Apparent cooperativity between human CMV virions introduces errors in conventional methods of calculating multiplicity of infection

brent.ryckman@mso.umt.edu (Brent Ryckman) — Wed, 05 Aug 2026 00:00:00 +0000

Whether infection of cells by individual virions occurs randomly, or if there is some form(s) of competition or cooperativity between individual virions, remains largely unknown for most virus–cell associations. Here, we studied cooperativity/competition for three different strains of human cytomegalovirus (HCMV) on two different cell types (fibroblasts and epithelial cells). By titrating viral inocula concentrations in small steps over several orders of magnitude, and by using flow cytometry to precisely measure the frequency of infected cells, we found that for most virus–cell associations, the frequency of cell infection increases faster than linear with an increasing inoculum concentration, indicating cooperativity between individual infecting virions. Mathematical modeling suggests that this apparent cooperativity cannot be explained by heterogeneity in either the infectivity of the individual virions or the resistance of individual cells to infection, or by simple aggregation/clumping of viral particles. Stochastic simulations of two additional alternative models that allow for (1) reduction in cell resistance to infection when exposed to multiple virions, or (2) compensation in infectivity of poorly infectious virions when coinfecting cells with more infectious virions, resulted in apparent viral cooperativity. Analysis of other published datasets suggests the presence of apparent viral cooperativity for HIV and vaccinia virus, infecting CRFK or HeLa cells, respectively, but not for tobacco mosaic virus forming plaques on plant leaves. We thus (1) propose a methodology to rigorously evaluate apparent cooperativity of viruses infecting target cells, and (2) demonstrate that knowing the degree of virus cooperativity for any given virus–cell combination is important for an accurate quantification of multiplicity of infection.

High-throughput quantification of population dynamics using luminescence

science@maltemuetter.ch (Daniel C Angst) — Wed, 05 Aug 2026 00:00:00 +0000

Bacterial population decline at antibiotic concentrations above the minimum inhibitory concentration (MIC) remains poorly characterized. This is because colony-forming units (CFU), the standard method to quantify inhibition, are slow, labor-intensive, and costly. Luminescence assays are widely used to quantify population dynamics at subinhibitory concentrations, yet their limitations and reliability at high concentrations remain underexplored. Here, we compared luminescence- and CFU-based rates in Escherichia coli across 20 antimicrobials. In our experiments, luminescence- and CFU-based rates did not differ significantly for half of them. For the other half, CFU-based decline rates were consistently higher. The estimates differed for two main reasons: First, because light intensity tracks biomass more closely than population size, luminescence declined more slowly than the population when bacteria filamented. Second, CFU-based estimates indicated a steeper decline when treatment reduced the number of colonies formed per plated bacterium. This can result from changes in clustering behavior, physiological changes that impair culturability, or antimicrobial carryover. Thus, the suitability of luminescence to quantify bacterial decline depends on the physiological effects of the antimicrobial and whether the quantity of interest is cell number or biomass. Within these limitations, luminescence can serve as an efficient, high-throughput alternative for quantifying bacterial dynamics at super-MIC concentrations.

Niche exclusion of a lung pathogen in mice with designed probiotic communities

collette2@llnl.gov (Adam P Arkin) — Tue, 04 Aug 2026 00:00:00 +0000

For years, the airway microbiota have been theorized to be gatekeepers of respiratory health, as pathogens entering the airway make contact with resident microbes prior to or coincident with their interaction with host cells. Thus, modification of the native airway community may serve as a means of altering the local environment in favor of health. In this work, we hypothesize that synthetic bacterial communities introduced into the airway can serve as prophylactic countermeasures against infection by Burkholderia thailandensis in mice. We demonstrate that understanding of antagonistic interactions between a pathogen and airway microbiota in vitro can guide identification of probiotics with protective capabilities in vivo. Specifically, we show that niche overlap between the probiotic and pathogen is indicative of probiotic performance in vivo. This work serves as a foundation for the rational design of probiotic communities for protection against and treatment of respiratory infections.

Reprogramming of host energy metabolism mediated by the TNF-iNOS-HIF-1α axis plays a key role in host resistance to Plasmodium infection

kelycatarine@gmail.com (Diego Luis Costa) — Mon, 27 Jul 2026 00:00:00 +0000

TNF has a dual effect in Plasmodium infection, bolstering the host's immune defense while also inducing sickness behavior. Here, we confirm that TNF signaling hampers physical activity, food intake, and energy expenditure while enhancing glucose uptake by the liver and spleen, as well as controlling parasitemia in Plasmodium chabaudi (Pc)-infected mice. We also report that TNF is required for expression of inducible nitric oxide synthase (iNOS), stabilization of hypoxia-inducible factor 1α (HIF-1α), expression of glucose transporter GLUT1, and enhanced glycolysis in monocytic cells from Pc-infected mice. Importantly, Pc-infected Nos2^-/-, TNFR1 cKO, and HIF-1a cKO mice show impaired release of TNF and glycolysis in monocytes, along with increased parasitemia and disease tolerance. Altogether, our results indicate that TNF-iNOS-HIF-1α-induced glycolysis in monocytes plays a critical role in host defense and sickness behavior in Pc-infected mice.

An abundant merozoite surface protein of Plasmodium falciparum modulates susceptibility to inhibitory antibodies

danny.wilson@adelaide.edu.au (Danny W Wilson) — Mon, 27 Jul 2026 00:00:00 +0000

Malaria merozoite surface proteins (MSPs) are thought to have important roles in red blood cell (RBC) invasion and their exposure on the parasite surface makes them attractive vaccine candidates. However, their role in invasion has not been directly demonstrated and their biological functions remain unknown. One of the most abundant merozoite surface proteins is PfMSP2, a likely ancestral protein that has been maintained in the Plasmodium falciparum lineage and is a focus of vaccine development. Using CRISPR-Cas9 gene editing, we removed PfMSP2 from two different P. falciparum lines with no impact on parasite replication or phenotype in vitro, demonstrating that it is not essential for RBC invasion. Interestingly, loss of PfMSP2 led to increased inhibitory potency of antibodies targeting other merozoite proteins involved in invasion, particularly PfAMA1. In a solid-phase model, increasing concentrations of PfMSP2 protein reduced binding of different antibodies against PfAMA1 in a dose-dependent manner. These data suggest that PfMSP2 can modulate the susceptibility of merozoites to protective inhibitory antibodies. The results of this study change our understanding of the potential functions of PfMSP2 and establish a new concept in malaria where a surface protein can reduce the protective efficacy of antibodies targeting a different antigen. These findings have important implications for understanding malaria immunity and informing vaccine development.

Enteropathogenic Escherichia coli-mediated fast and coordinated Ca^²+ responses regulate NF-κB activation

guy.tranvannhieu@i2bc.paris-saclay.fr (Fangrui Guo) — Wed, 22 Jul 2026 00:00:00 +0000

Enteropathogenic Escherichia coli (EPEC) is a major bacterial enteropathogen causing infectious diarrhea among children in developing countries. Here, we found that EPEC induced isolated Ca²⁺ responses in epithelial cells, triggered by extracellular ATP (eATP). These responses were dependent on type III secretion (T3S) and down-regulated by the bacterial secreted protease EspC, consistent with eATP released by the T3S translocon pore-forming activity in host membranes. By performing high-speed Ca²⁺ imaging, we uncovered that at the onset of infection, low eATP levels triggered Ca²⁺-responses involving the whole cell but showing small amplitude and fast kinetics usually associated with local Ca²⁺ responses. The findings, supported by theoretical modeling, evoke a conceptual shift whereby low amounts of inositol 1, 4, 5-trisphosphate (IP₃) induced by low eATP levels and subsequent moderate Ca²⁺ release enable the fast coordination of IP₃ receptor cluster activation throughout the cell. Importantly, these yet undescribed coordinated fast responses occurred over prolonged time periods and defined a cell state with dampened activation of the pro-inflammatory transcriptional activator NF-kB associated with a decrease in its Ca²⁺-dependent O-linked β-N-acetylglucosamine modification.

The adaptive landscapes of three global Escherichia coli transcriptional regulators

caua.westmann@ieu.uzh.ch (Andreas Wagner) — Tue, 21 Jul 2026 00:00:00 +0000

The evolution of gene regulation is a major source of evolutionary adaptation and innovation, particularly when organisms encounter new or changing environments. Central to this process is the emergence of new transcription factor binding sites (TFBSs). Adaptive landscapes provide a powerful framework to study such emergence by linking regulatory DNA sequences to their transcriptional outputs. Although several landscapes have been characterized for DNA, RNA, and proteins, large-scale in vivo adaptive landscapes for bacterial TFBSs remain scarce. Here, we address this gap by experimentally mapping the first comprehensive in vivo regulatory landscapes for three global transcription factors in Escherichia coli: cAMP receptor protein, Fis, and IHF. Using a massively parallel reporter assay, we quantify the regulation strength of more than 30,000 TFBS variants for each factor, and reconstruct their adaptive landscapes. All three landscapes are highly rugged and exhibit pervasive epistasis, with thousands of local peaks distributed broadly across sequence space. This ruggedness contrasts sharply with the much smoother TFBS landscapes of eukaryotes. It suggests greater constraints on the evolution of prokaryotic gene regulation. Nonetheless, evolutionary simulations show that ~10% of evolving populations can reach a peak of strong regulation, a proportion that is significantly greater than in comparable random landscapes. Adaptive evolution starting from the same DNA sequence can attain different high peaks, and some peaks are reached more frequently than others. Together, our results show that de novo adaptive evolution of new gene regulation in bacteria is feasible, but subject to a blend of chance, historical contingency, and evolutionary biases.

Reactive oxygen detoxification contributes to Mycobacterium abscessus antibiotic survival

bhpenn@health.ucdavis.edu (Abigail Ray) — Tue, 21 Jul 2026 00:00:00 +0000

When a population of bacteria is exposed to a bactericidal antibiotic, most cells die rapidly. However, a subpopulation of antibiotic-tolerant cells known as ‘persister cells’ can survive for prolonged periods. In addition, antibiotic tolerance can be broadly induced throughout the population by stresses such as nutrient deprivation. However, the pathways required to maintain viability in this setting and how stress induces antibiotic tolerance are both poorly understood. To identify genetic determinants of antibiotic tolerance in mycobacteria, we carried out transposon insertion sequencing (Tn-Seq) screens in Mycobacterium abscessus (Mabs) exposed to bactericidal translation-inhibiting antibiotics. This analysis identified genes essential for the survival of both spontaneous persister cells, as well as for stress-induced tolerance, allowing the first genetic comparison of these states in mycobacteria. Pathway analysis identified multiple genes involved in the detoxification of reactive oxygen species (ROS), including the catalase-peroxidase katG, which contributed to survival in both unstressed and nutrient-starved cells. In addition, we found that endogenous ROS were generated by translation-inhibiting antibiotics, and that hypoxia impaired bacterial killing. KatG specifically contributed to survival following exposure to transcription or translation inhibitors, but not other antibiotic classes tested. Thus, the lethality of some antibiotics is amplified by toxic ROS accumulation, and antibiotic-tolerant cells require detoxification systems in order to remain viable. These findings further demonstrate that antibiotic-induced ROS plays a broad role in mediating antibiotic lethality across diverse organisms.

RNA selectively modulates activity of virulent amyloid PSMα3 and host-defense LL-37 via phase separation and aggregation dynamics

meytal.landau@desy.de (Alexander Kai Buell) — Mon, 20 Jul 2026 00:00:00 +0000

Amyloid-forming peptides are increasingly recognized as dynamic regulators at the host–pathogen interface, yet how environmental factors control their assembly and activity remains poorly understood. Here, RNA acts as a concentration-dependent regulator of two sequence-related α-helical peptides with fundamentally different assembly behaviors: the cross-α amyloid-forming Staphylococcus aureus virulence factor PSMα3 and the non-amyloidogenic human host-defense peptide LL-37. RNA drives PSMα3 through distinct assembly states, from liquid-like condensates to fibrillar polymorphs, while preserving cytotoxic and antimicrobial activity over time. In contrast, RNA attenuates LL-37 cytotoxicity toward host cells while maintaining antibacterial activity, consistent with a host-protective immunomodulatory effect. Together with the opposing effects of epigallocatechin gallate, which redirects both peptides into amorphous assemblies, these findings support a mechanistic model in which biological activity is governed by supramolecular architecture, assembly trajectory, and dynamics rather than by monomer abundance or mature fibrils alone. More broadly, our findings identify RNA as an environmental regulator of α-helical peptide assemblies, and establish assembly-state control as a tunable determinant of virulence and host defense.

The targeted cytosolic degradation of class I histone deacetylases is essential for efficient alphaherpesvirus replication

zenglei2021918@163.com (Bei-Bei Chu) — Thu, 09 Jul 2026 00:00:00 +0000

Viral infection triggers a robust DNA damage response (DDR), reshaping the host chromatin landscape to facilitate viral replication. Here, we uncover a novel mechanism by which alphaherpesviruses exploit the DDR pathway. We demonstrated that herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV) induced selective degradation of class I histone deacetylases (HDAC1/2), leading to histone hyperacetylation and subsequent DDR activation. Strikingly, viral infection promoted nuclear export of HDAC1/2, followed by MDM2-mediated K63-linked polyubiquitination and proteasomal degradation in the cytoplasm. Pharmacological inhibition of either DDR signaling or HDAC1/2 nuclear export significantly affected viral replication in vitro and in vivo. Our findings reveal a unique viral strategy to hijack host epigenetic regulation for efficient replication, and identify potential therapeutic targets for alphaherpesvirus infections.

Inferring variant-specific effective reproduction numbers from combined case and sequencing data

marlinfiggins@gmail.com (Marlin D Figgins) — Thu, 09 Jul 2026 00:00:00 +0000

Accurately estimating relative transmission rates of SARS-CoV-2 variants remains a scientific and public health priority. Recent studies have used the sample proportions of different variants from genetic sequence data to describe variant frequency dynamics and relative transmission rates, but frequencies alone cannot capture the rich epidemiological behavior of SARS-CoV-2. Here, we extend methods for inferring the effective reproduction number of an epidemic using confirmed case data to jointly estimate variant-specific effective reproduction numbers and frequencies of co-circulating variants using cases and sequences across states in the United States from January 2021 to March 2022. Our method can be used to infer structured relationships between effective reproduction numbers across time series, allowing us to estimate fixed variant-specific growth advantages. We use this model to estimate the effective reproduction number of SARS-CoV-2 variants of concern and variants of interest in the United States, and to estimate consistent growth advantages of particular variants across different locations.

Canonical and phosphoribosyl ubiquitination coordinate to stabilize a proteinaceous structure surrounding the Legionella-containing vacuole

Shaeri.Mukherjee@ucsf.edu (Adriana Steinbach) — Wed, 08 Jul 2026 00:00:00 +0000

Legionella pneumophila (L.p.), an intracellular bacterial pathogen, hijacks the ubiquitin signaling network of its eukaryotic host cells to establish infection. Two families of L.p. secreted ubiquitin ligases are instrumental in the maturation of the Legionella-containing vacuole (LCV): the SidC/SdcA family, which catalyzes canonical ubiquitination, and the SidE family, which bypasses the E1-E2-E3 enzymatic cascade and directly conjugates ubiquitin to a target through a phosphoribosyl (PR) linkage. Here, we demonstrate that the coordinated activities of these two effector families generate a hyperstable, ubiquitin-rich structure surrounding the LCV. We propose a model in which an initial wave of SidC/SdcA-mediated canonical ubiquitination around the LCV is further modified by SidE family-driven PR-ubiquitination, resulting in a detergent-resistant ‘cloud’. The ‘cloud’ is transient, breaking down as infection progresses, suggesting that L.p. reshapes the properties of the proteinaceous shell surrounding the vacuole to meet changing needs throughout its intracellular lifecycle. This unusual structure likely stabilizes and protects the LCV, shielding it from host defense mechanisms during early infection. Our findings reveal cellular consequences of effector interplay during infection and provide a foundation for future studies into the structure and function of the proteinaceous ‘cloud’ surrounding the LCV.

Correlates of protection against African swine fever virus identified by a systems immunology approach

artur.summerfield@unibe.ch (Artur Summerfield) — Mon, 29 Jun 2026 00:00:00 +0000

African swine fever virus (ASFV) causes a fatal hemorrhagic disease in domestic pigs and wild boars, which poses severe threats to the global pork industry. Despite the promise of live attenuated vaccines (LAVs), their narrow margin between efficacy and residual virulence presents major safety challenges. This study bridges a critical knowledge gap in ASF vaccinology by identifying innate and adaptive correlates of protection. This was achieved by using an established model with two groups of pigs differing in baseline immunological status (farm and specific pathogen-free [SPF]). The animals were immunized with an attenuated ASFV strain and subsequently challenged with a related, highly virulent genotype II strain. By applying a systems immunology approach, we correlated kinetic data, including serum cytokines, blood transcription modules (BTMs), T-cell responses, and antibody levels, with clinical outcomes to track protective and detrimental immune responses to the virus over time. Key innate correlates of protection included early and sustained IFN-α response, activation of antigen presentation BTMs, and controlled IL-8 levels during immunization. Lower baseline immune activation observed in SPF pigs in steady state was linked to increased protection. Adaptive correlates encompassed cell cycle, plasma cell, and T-cell BTM responses lasting until day 15 post-immunization. Consequently, an effective response from ASFV-specific T_h cells prior to challenge indicated protection. After the challenge, an early IFN-α response, along with low levels of pro-inflammatory cytokines and a strong induction of memory T_h and T_c cells, correlated with improved clinical outcomes. The model highlights the critical role of host-specific factors in vaccine efficacy and provides a valuable framework for optimizing ASFV vaccine design while distinguishing between protective and detrimental immune responses.

Estimating probabilities of malaria importation in southern Mozambique through modelling P. falciparum genomics and mobility patterns

arnau.pujol@isglobal.org (Alfredo Mayor) — Fri, 26 Jun 2026 00:00:00 +0000

Imported malaria is a critical obstacle to achieving elimination in low transmission settings, but importation classification tools combining human mobility and parasite genomics are lacking. A Bayesian model combining epidemiological, human mobility, and parasite genetic data was developed to estimate malaria importation and geographic origins of Plasmodium falciparum cases. Using microhaplotype-based genetic relatedness from 1605 samples across nine Mozambican provinces in 2022, the study focused on two low-transmission districts in the south: Magude and Matutuine. Parasites from southern Mozambique showed lower genetic relatedness to those from northern/central regions (0.021) than the national average (0.034, p<0.001), indicating limited connectivity. Overall, 42% (88/207) of infections in these districts were classified as imported, mainly originating from Inhambane province (63% [55/88]). Imported cases showed higher parasite complexity than local ones (odds ratios [OR] = 1.3). Importation rates differed markedly between districts – Matutuine (48.60%, 87/179) was far more affected than Magude (10.71%, 3/28) – highlighting the need for localised rather than uniform elimination strategies. In Matutuine, importation appears to be actively sustaining transmission, suggesting that reducing malaria burden in source regions (particularly Inhambane) and targeting travellers from central and northern Mozambique would have the greatest elimination impact.

Mycobacterium tuberculosis partitions the Krebs cycle under iron starvation

serafinia@yahoo.it (Acely Garza-Garcia) — Thu, 25 Jun 2026 00:00:00 +0000

In this study, we investigated how iron limitation alters central metabolism in Mycobacterium tuberculosis using metabolomics and stable isotope tracing. Our findings reveal a well-orchestrated metabolic programme to enable Krebs cycle activity despite the inefficient action of its iron-dependent enzymes. Under such conditions, carbon flux through the oxidative branch of the Krebs cycle is stalled, resulting in the accumulation of metabolites that are partially secreted. As a result, carbon flux from glycolysis is partially diverted to the reductive branch of the Krebs cycle to support the production of oxaloacetate and malate through the activity of phosphoenolpyruvate carboxykinase and pyruvate carboxylase. Both branches terminate with the synthesis of malate, which is secreted. This unprecedented split of the Krebs cycle and malate secretion in a bacterial pathogen facilitates the continuous flow of carbon through the core of carbon metabolism, overcoming the metabolic stalling triggered by iron starvation.

From multiplicity of infection to force of infection in sparsely sampled high-transmission Plasmodium falciparum populations

qz1111@stanford.edu (Karen P Day) — Tue, 23 Jun 2026 00:00:00 +0000

High multiplicity of infection (MOI), the number of genetically distinct parasite strains co-infecting a host, characterizes falciparum malaria and other infectious diseases under high transmission. High MOI in Plasmodium falciparum accompanies high prevalence of asymptomatic infection despite high exposure, creating a large transmission reservoir that challenges intervention. This pattern is enabled by parasite immune evasion through extensive antigenic diversity. The force of infection (FOI), the number of new infections acquired by an individual host over a given time interval, is the dynamic counterpart of MOI and a key epidemiological parameter for monitoring antimalarial interventions. FOI is difficult and costly to measure, especially in high-transmission regions, requiring cohort studies or model-based inference from repeated cross-sectional surveys. Here, we apply queuing theory to estimate FOI from MOI with two approaches: a two-moment approximation and Little’s Law. We illustrate these methods using MOI estimates obtained under sparse sampling schemes with the ‘varcoding’ approach. Both methods rely on infection duration data from naive malaria therapy patients and are therefore suitable for subpopulations with limited immunity, such as toddlers. We evaluate their performance using output from a stochastic agent-based model and apply the methods to an interrupted time-series study in northern Ghana, before and immediately after a three-round transient indoor residual spraying intervention. By accounting for sampling limitations with a Bayesian framework and bootstrap imputation, both methods yield good and replicable FOI estimates across various simulated scenarios. Their application to the surveys of 1- to 5-year-old children in Ghana indicates a larger than 70% reduction in annual FOI immediately after intervention.

Enterovirus D68 2A protease causes nuclear pore complex dysfunction and independently contributes to motor neuron toxicity

Elrick@kennedykrieger.org (Jeffery D Rothstein) — Thu, 18 Jun 2026 00:00:00 +0000

Enterovirus D68 (EV-D68) is an important pathogen associated with acute flaccid myelitis (AFM). The pathogenesis of AFM involves infection of spinal motor neurons and motor neuron death; however, the mechanisms linking EV-D68 infection to selective neurotoxicity are not well understood. Dysfunction of the nuclear pore complex (NPC) has been implicated in motor neuron injury in neurodegenerative diseases such as amyotrophic lateral sclerosis, and the NPC is also modified by picornavirus proteases during infection. We therefore sought to determine the impact of EV-D68 proteases on NPC composition and function. We demonstrate widespread disruption of NPC composition by EV-D68 2A and 3C proteases via direct cleavage of a relatively small number of nucleoporins, notably Nup98 and POM121, by 2A^pro. Using reporter systems, we demonstrate that 2A^pro inhibits nuclear transport of protein cargoes and disrupts the permeability barrier of the NPC, while having no apparent effect on RNA export. Independently, we show 2A^pro is toxic to induced pluripotent stem cell-derived motor neurons by demonstrating a rescue of toxicity with the 2A^pro inhibitor telaprevir at concentrations insufficient to inhibit viral replication. These findings expand our understanding of EV-D68 neuropathogenesis and provide a rationale for studying the NPC or 2A^pro as therapeutic targets in AFM.

A rapid transfer of virions coated with heparan sulfate from the ECM to CD151 defines an early step in the human papillomavirus infection cascade

lflorin@uni-mainz.de (Annika Massenberg) — Tue, 16 Jun 2026 00:00:00 +0000

Human Papillomaviruses (HPVs) are the underlying cause of several types of cancer; albeit, they are mostly known for their association with cervical carcinoma. The virions reach their target cells through a break in the epithelial barrier. After binding to heparan sulfate (HS) of the extracellular matrix (ECM), they are recruited via actin-dependent mechanisms to the cell surface, where they co-internalize with the entry factor CD151. The in vivo occurring active recruitment from the ECM to the cell surface may be bypassed in cell culture, where virions reach the cell surface simply by passive diffusion. To specifically investigate these early events of the infection cascade, we use HaCaT keratinocytes as they produce a robust ECM enabling abundant virion binding to ECM components such as HS before transfer to cell surface receptors and infection. Employing microscopy, we focus on the basal membrane that for virions is difficult to access by diffusion. We block the active recruitment from ECM attachment sites to the cell body, release the blocking, and monitor the association of virions with CD151 or HS. We observe quick virion recruitment from the ECM to the cell body within 15 min. During recruitment, virions associate with the tetraspanin CD151 present at the cell border or at filopodia. These virions are decorated with HS, which they lose in the next few hours, presumably prior to endocytosis. Our observations reveal a rapid step in the HPV infection cascade: the transfer of HS-coated virions from the ECM to CD151. This step is too fast to account for the asynchronous uptake of HPVs, which is likely driven by glycan and capsid processing.