Virulence factors are molecules produced by
pathogens (
bacteria,
viruses,
fungi and
protozoa) that contribute to the pathogenicity of the organism and enable them to achieve the following:
- colonization of a niche in the host (this includes attachment to cells)
- immunoevasion, evasion of the host's immune response
- immunosuppression, inhibition of the host's immune response
- entry into and exit out of cells (if the pathogen is an intracellular one)
- obtain nutrition from the host