How microorganisms enter a host and how they damage host cells with exotoxins?

How microorganisms enter a host and how they damage host cells with exotoxins?

To cause disease most pathogens must: 
 gain access to the host 
 gain access to the tissue
 evade host defences 
 damage the host tissue 

• Some microbes cause disease without invading the body • Portals of entry - gaining entrance to the human body (and other hosts) through several avenues
Adhesins/ligands bind to receptors on host cells
The host cell cytoskeleton provides the mechanism: • Actin is used:  to penetrate host cells  to move through and between host cells
Invasins – Salmonella alters host actin to enter a host cell
Use actin to move from one cell to the next – Listeria
Cadherin: bridges membrane junctions
Exotoxins 

• Antibodies: 
 provide immunity to exotoxins • Inactivated exotoxins: 
 can no longer cause disease 
 can still stimulate the body to produce exotoxins 

• These altered exotoxins are called toxoids 
 toxoids (as vaccines) stimulate antitoxin production (immunity) 
 Vaccines – stimulate antitoxin production
Exotoxins 

• Are named on the basis of many characteristics: 
 neurotoxins - nerve cells 
 cardiotoxins - heart cells
 hepatotoxins - liver cells 
 leukotoxins - leukocytes 
 enterotoxins - the lining of the gastrointestinal tract 
 cytotoxins - a wide variety of cells diphtheria toxin (cause of diphtheria) botulinum toxin (Clostridium botulinum) vibrio enterotoxin (Vibrio cholerae)

**REMEMBER TO STAY POSITIVE LIKE A PROTON!!**