Virulence factors are important in bacteria, allowing them to become pathogenic in a host. This can include invasin proteins, allowing the pathogen to break open cells in the host to liberate nutrients and minerals necessary for its growth.
Adhesins may also be produced by the pathogen, particularly if it is found in an area with high fluid flow (such as the genito-urinary tract). Adhesins allow the bacteria to stick (adhere) to the cells (such as epithelium in the GU tract), preventing it from being washed away by micturition.
Haemolysins are used by bacteria that infect blood, allowing them to burst erythrocytes (red blood cells) to release the haemoglobin. This is a beneficial process, as it liberates iron, which can then be taken up by the bacteria’s siderophores.
Endotoxins can be synthesised by bacteria, such as LPS, activating immune cells. This can result in an inflammatory response occurring, releasing histamine from mast cells. Histamine release can be painful, causing a disease as an autoimmune response.