plaqueforming

Plaqueforming is a term used in microbiology to describe the ability of microorganisms to form plaques—visible clearings or structured biofilms—depending on the context. The concept is most commonly encountered in two domains: dental science and virology.

In dental science, plaqueforming refers to the development of dental plaque, a biofilm that adheres to tooth surfaces. Plaque formation begins with the acquired enamel pellicle, followed by adhesion and proliferation of early colonizers such as Streptococcus species. Over time, the biofilm matures into a complex, multispecies community embedded in a self-produced extracellular matrix. Plaque accumulation is influenced by factors including saliva flow, dietary carbohydrates, oral hygiene practices, and host immune factors. Clinically, excessive plaque is associated with dental caries and periodontal disease if not effectively managed. Assessment of plaque can be performed with visual indices or disclosing agents, and prevention focuses on mechanical disruption of the biofilm and, when appropriate, chemical aids like chlorhexidine.

In virology and phage research, plaqueforming describes the formation of plaques on a lawn of susceptible bacteria, a key method for quantifying infectious virus particles. A plaque-forming unit (PFU) corresponds to a single infectious virion that initiates a productive infection under assay conditions. Plaques arise from localized bacterial lysis or growth inhibition, forming clear zones that can be counted to estimate viral concentration. Plaque assays are used to titrate viruses, characterize lytic activity, and evaluate phage therapy candidates. Variables such as host strain, agar concentration, incubation temperature, and timing affect plaque morphology and counts.

See also: dental plaque, biofilm, plaque assay, plaque-forming unit.