pathogenins

Pathogenins are a proposed class of molecular agents produced by pathogenic organisms that modulate host biology to favor infection. The term is not universally standardized and is sometimes used informally to describe a broad range of virulence factors, including secreted proteins, toxins, effector molecules delivered by secretion systems, and certain small molecules or nucleic acid–based effectors.

In practice, pathogenins can belong to several categories. Proteins and peptides are commonly delivered into host cells or the extracellular milieu via specialized secretion systems in bacteria or fungi, acting as effectors to alter signaling pathways, cytoskeletal dynamics, vesicular trafficking, or immune responses. Small-molecule toxins and metabolites can disrupt cellular processes or metabolism. Some studies also consider nucleic acid–based molecules and extracellular vesicle cargo as pathogenins due to their roles in communication and manipulation of host cells.

Mechanisms of action commonly attributed to pathogenins include suppression or misdirection of innate immune signaling, interference with inflammatory responses, induction of programmed cell death, and reprogramming of host metabolism to support pathogen survival. The exact repertoire of pathogenins and their targets varies across pathogens and host species, reflecting evolutionary adaptation and host specificity.

Research on pathogenins spans genomics, proteomics, and functional screening in cell- and organism-based models. Because the term encompasses a broad and evolving set of factors, it is often useful in discussions of virulence to refer to pathogenins as a collective concept rather than as a single defined class. Related topics include virulence factors and pathogen–host interactions.