Virulence gene

Definition

A virulence gene is a gene that encodes factors enabling a microorganism to establish an infection, cause disease, or evade host defenses. These genes contribute to the pathogenicity of the organism.

5 Must Know Facts For Your Next Test

1. Virulence genes can be transferred between bacteria through horizontal gene transfer mechanisms such as conjugation, transformation, and transduction.
2. These genes often reside on mobile genetic elements like plasmids, transposons, or pathogenicity islands.
3. The expression of virulence genes can be regulated by environmental signals and quorum sensing.
4. Virulence factors encoded by these genes include toxins, adhesins, invasins, and immune evasion molecules.
5. Mutations in virulence genes can either attenuate or enhance the pathogenicity of microorganisms.

Review Questions

• What are some mechanisms through which virulence genes can be horizontally transferred between bacteria?
• How do environmental signals influence the expression of virulence genes?
• What types of virulence factors are typically encoded by virulence genes?

Related terms

Horizontal Gene Transfer: The movement of genetic material between organisms other than by vertical transmission (from parent to offspring).

Pathogenicity Island: A distinct class of genomic island acquired by microorganisms through horizontal gene transfer that contains clusters of virulence genes.

Quorum Sensing: A system of stimulus and response correlated to population density used by bacteria for regulating gene expression, including that of virulence genes.