Virulence factor

Definition

A virulence factor is a molecule or structure produced by a pathogen that contributes to its ability to cause disease. These factors enable the pathogen to invade the host, evade the immune system, and obtain nutrients from the host.

5 Must Know Facts For Your Next Test

1. Virulence factors include toxins, enzymes, and surface proteins like adhesins.
2. Horizontal gene transfer can spread virulence factors among bacterial populations.
3. Bacteria such as Streptococcus pneumoniae use capsules as a virulence factor to resist phagocytosis.
4. Viruses may have virulence factors like viral proteins that inhibit host immune responses.
5. Fungal pathogens often produce enzymes like proteases and lipases that degrade host tissues.

Review Questions

• What are three examples of bacterial virulence factors?
• How do viruses utilize their virulence factors to evade the host immune system?
• What role does horizontal gene transfer play in the spread of virulence factors?

Related terms

Pathogenicity: The ability of an organism to cause disease.

Adhesins: Surface proteins used by microbes to adhere to host cells.

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