Virulence factor
Virulence factors (preferably known as pathogenicity factors or effectors in botany) are cellular structures, molecules and regulatory systems that enable microbial pathogens (bacteria, viruses, fungi, and protozoa) to achieve the following: colonization of a niche in the host (this includes movement towards and attachment to host cells) immunoevasion, evasion of the host's immune response immunosuppression, inhibition of the host's immune response (this includes leukocidin-mediated cell death) entry into and exit out of cells (if the pathogen is an intracellular one) obtain nutrition from the host Specific pathogens possess a wide array of virulence factors. Some are chromosomally encoded and intrinsic to the bacteria (e.g.