Pathotype

Definition

A group of pathogen strains distinguished from other strains of the same species by distinctive virulence characteristics, host range, or disease phenotype on particular hosts; used infrasubspecifically to classify pathogenic variants without implying formal taxonomic rank.

Etymology

From Greek pathos (suffering, disease) + typos (mark, model, type)

Example

Different pathotypes of the entomopathogenic bacterium Bacillus thuringiensis are distinguished by their specific toxicity to lepidopteran, coleopteran, or dipteran hosts, each producing characteristic crystal proteins active against particular insect orders.

Synonyms

• pathovar

Related Terms

• Biotype
• strain
• serotype
• Virulence
• host specificity
• entomopathogen
• infrasubspecific

Usage Notes

Pathotype and pathovar are often used interchangeably in practice, though 'pathovar' is formally sanctioned in bacterial nomenclature for plant pathogens (e.g., Xanthomonas campestris pv. vesicatoria). Pathotype has broader application across viruses, fungi, and nematodes affecting insects. The term designates phenotypic similarity in pathogenicity rather than genetic relatedness; genetically divergent strains may belong to the same pathotype, and closely related strains may differ in pathotype. Contrast with 'biotype' (physiological or morphological variant) and 'serotype' (antigenic variant). In entomopathology, pathotype classification guides biological control selection, as host range determines which pest species a microbial agent will attack.