Virulence factors help bacteria• invade the host• cause disease• evade host defenses.Include:7. Attachment (via adhesins)8. Colonization9. Invasiveness10. Toxins & Enzymes11. Inhibition of Phagocytosis
(Attachment (via adhesins-1They allow bacteria to bind to host cells : Cilia - motion• fimbriae• some bacterial cell walls• capsulesThese adhesins bind to specific epithelium receptors or they are able to maintain even closer contact. Flagellum - motion
A Cell Wall –Flagellum - protection,motion invasion, evasion Cell Parts D B Ribosome – production of Cilia - motion toxins/attachment proteins on cell wall
2-Colonization• The Ability to Adhere to Host Cells and Resist Physical Removal or• the establishment of the pathogen at the appropriate portal of entry.• Pathogens usually colonize host tissues that are in contact with the external environment.
Virulence Factors that Promote Bacterial Colonization:3. Using Pili (fimbriae) to Adhere to Host Cells4. Using Adhesins to Adhere to Host Cells5. Using Biofilms to Adhere to Host Cells
Invasiveness-3• the ability of a pathogen to invade tissues.• Invasiveness encompasses(1) mechanisms for colonization (adherence and initial multiplication),(2) production of extracellular substances ("invasins"), that promote the immediate invasion of tissues(3) ability to bypass or overcome host defense mechanisms which facilitate the actual invasive process.
4-Toxins &EnzymesToxins• They are products of a pathogen that destroy/ damage/• inactivate one or more vital component of the host.• Classes of toxinsNeurotoxinsEnterotoxinsCytotoxins
EnzymesExcretion of certain pathogens to assist them in establishing infection and producing a disease.There are virulence determinant enzymes that dissolve the glue between cells, thus allowing the bacteria to spread rapidly through the tissue.