Some are chromosomally encoded and intrinsic to the bacteria (e.g. capsules and endotoxin), whereas others are obtained from mobile genetic elements like plasmids and bacteriophages (e.g. some exotoxins).
Virulence factors encoded on mobile genetic elements spread through horizontal gene transfer, and can convert harmless bacteria into dangerous pathogens.
It has been found that many pathogens have converged on similar virulence factors to battle against eukaryotic host defenses.
Capsules, made of carbohydrate, form part of the outer structure of many bacterial cells including Neisseria meningitidis.
Capsules play important roles in immune evasion, as they inhibit phagocytosis, as well as protecting the bacteria while outside the host.
Experimental research, for example, often focuses on creating environments that isolate and identify the role of "niche-specific virulence genes".
[6] Some bacteria, such as Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa, produce a variety of enzymes which cause damage to host tissues.
The other process is irreversible, using toxins to completely change the target GTPase and shut down or override gene expression.
It does not modify anything, but overdrives normal cellular internalization process, making it easier for the Bacteria to be colonized within a host cell.
As glycolipids (as opposed to peptides), endotoxins are not bound by B or T-cell receptors and do not elicit an adaptive immune response.
Some bacteria secrete exotoxins, which have a wide range of effects, including inhibiting certain biochemical pathways in the host.
Examples of virulence factors for Staphylococcus aureus are hyaluronidase, protease, coagulase, lipases, deoxyribonucleases and enterotoxins.
Examples for Yersinia pestis are an altered form of lipopolysaccharide, type three secretion system, and YopE and YopJ pathogenicity.
The cytolytic peptide Candidalysin is produced during hyphal formation by Candida albicans; it is an example of a virulence factor from a fungus.