A bacterial pathogen is usually defined as any bacterium that has the capacity to cause disease. Its ability to cause disease is called pathogenicity.
Virulence provides a quantitative measure of the pathogenicity or the likelihood of causing disease.
Virulence factors refer to the properties (i.e., gene products) that enable a microorganism to establish itself on or within a host of a particular species and enhance its potential to cause disease. Virulence factors include bacterial toxins, cell surface proteins that mediate bacterial attachment, cell surface carbohydrates and proteins that protect a bacterium, and hydrolytic enzymes that may contribute to the pathogenicity of the bacterium.

VFDB是面向细菌的一个毒力数据库