Bacterial defence systems are diverse and form major barriers to horizontal gene transfer and bacteriophage (phage) infection. Though restriction-modification systems were the first such defences disc...

Bacterial antiviral immunity systems can be toxic to their hosts and must be tightly regulated. Immunity genes are often encoded by AT-rich mobile genetic elements subjected to silencing by nucleoid b...

Gram-negative bacteria deploy type VI secretion systems (T6SSs) to mediate interbacterial competition. Although numerous T6SS effectors have been identified, their pan-genomic repertoires and evolutio...

Most of our knowledge about bacterial functional roles in microbiomes comes from bulk measurements. Yet microbial communities are complex ecosystems in which functionally distinct bacterial subpopulat...

The phage-encoded protein PptA enables its DNA to masquerade as the host and evade cleavage, providing a potential foundation for engineering therapeutic phages that could bypass this widespread defence system.

Alt: Animated E. coli Bacteria Drawing

Bacteria produce natural products to adapt to their environments, with phage interactions as major ecological and evolutionary drivers. While some nat…

Gabija acts early during phage infection, preventing phage genome circularization and replication. Phage DNA end-binding proteins prevent RecBCD loading onto linear DNA, and the absence of RecBCD lice...

Ge et al. develop a receptor-centered strategy to identify phage proteins that target host receptors during infection and discover the λ outer-membrane protein Lom. Lom binds and occludes LamB, blocki...

OLD, an abortive immunity protein from prophage P2, consists of an ABC ATPase sensor and a TO-PRIM nuclease effector - a core architecture shared by a large protein family, including components of ant...

Phages often degrade the genome of their bacterial host to individual nucleotides. Here we describe Metis, a bacterial defense system that directly senses phage-mediated host genome degradation. Metis...

PALACE combines homology features and deep learning to improve phage assembly from metagenomics.

DNA repair proteins are repeatedly repurposed for antiviral immunity. In this issue of Cell Host & Microbe, Bell et al. utilized phylogenetic reconstruction of the evolutionary routes of the YprA repa...

Defense-associated reverse transcriptases (DRTs) employ DNA synthesis to protect bacteria against phage infection. We previously showed that DRT10, a tripartite system comprising an RT, a noncoding RNA (ncRNA), and a SLATT effector protein, catalyzes protein-primed, tandem-repeat DNA synthesis in a mechanism strikingly analogous to eukaryotic telomerase. However, the structural basis by which the RT-ncRNA complex directs repeat addition processivity and controls repeat length remains unknown. Here we present cryo-EM reconstructions of two evolutionarily diverse DRT10 RT-ncRNA systems that reveal an unanticipated 2:1 architecture, wherein two RT monomers bind opposite sides of a single, pseudo-symmetric ncRNA. Biochemical experiments demonstrate that each RT monomer reverse transcribes the template encoded on its respective side of the ncRNA, but only one generates the long repetitive product, with the template sequence defined by the distance between two flanking stem-loop anchors. Together with earlier studies of DRT2, DRT3, and DRT9, our findings identify a conserved mechanistic logic underlying ncRNA-templated tandem-repeat synthesis across Class 2 UG antiviral systems, despite vastly different architectural solutions. ### Competing Interest Statement Columbia University has filed a patent application related to this work. S.H.S. is a co-founder and scientific advisor to Dahlia Biosciences, a scientific advisor to CrisprBits and Prime Medicine, and an equity holder in Dahlia Biosciences and CrisprBits. The remaining authors declare no competing interests.

The eORFeome, a large-scale collection of open reading frames encoding viral proteins and secreted bacterial and parasite effectors, enables functional genomics across diverse pathways and pathogens. ...

Many bacterial anti-phage defence systems are encoded by mobile genetic elements, yet much of this antiviral repertoire remains undiscovered. Antimicrobial-resistance plasmids are well known for disse...

Genetic manipulation of bacteriophages is essential for interrogating phage biology and advancing antimicrobial therapies. However, current genome editing approaches can be inefficient, require multip...

The activation of an antiphage defence system relies on host factors targeted by phages, a mechanism analogous to the way that eukaryotic innate immune systems detect pathogen-induced perturbations of...

CRISPR-Cas adaptive immunity systems provide defense against mobile genetic elements and are often countered by diverse anti-CRISPR (Acr) proteins....

Nature Reviews Microbiology, Published online: 20 May 2026; doi:10.1038/s41579-026-01318-7The life cycle of temperate bacteriophages involves lytic or lysogenic cycles and has historically served as a model for studying genetic regulation. This Review provides an updated overview of these cycles and highlights their complexities, supporting a greater appreciation of the ecological roles of temperate phages.

Over three decades, rapid expansion of the transposable element ISL3 has reshaped Enterococcus faecium, which helps to explain this pathogen’s growing clinical threat.

Phages employ diverse counter-defense strategies to overcome bacterial immune systems. Here, the authors reveal that the phage homing nuclease SegB facilitates immune evasion by promoting the segmenta...

npj Viruses - Rage against the mean: a perspective on measuring fitness of individual phage particles