Lecture 3 Flashcards
once in the body what kind of cell do bacteria usually adhere to?
Epithelial cells
after establishment, through where do bacteria spread?
through tissues or via the lymphatic system
what are the 4 steps to the infection process?
- adhere to host cell
- spread
- survive defenses
- transfer to new host
what are some negatives for bacteria when it comes to attachment?
attachment could stimulate immune cell infiltration, activation, and phagocytosis
what are the components of adhesion for bacteria?
consists of lectin carbohydrate associations or Beta 1 integrins via ECM components for indirect association
direct interaction between what can allow bacterial entry into a host cell?
direct interaction between host integrin or cadherin receptors with bacteria surface ligand
what are the 4 big classes of the ECM?
collagen, fibronectin, laminin, and proteoglycan
what makes up collagen fibers and what about this set up is special?
it is 3 left hand helises wound to make fibrils which come to form the collagen fibers and all this winding gives it tensile strength
what is the make up of proteoglycans?
starts with a central molecule of hyaluronic acid, connected to this are then core proteins and connected to core proteins are sugars either chondroitin sulfate or keratan sulfate
what are some traits of fibronectin?
heterodimer but very close to being a homodimer, 2 proteins connected by disulfide bonds
what are some traits for laminin?
creates basal lamina which is foundation for cells to sit on, involved in general interaction and signaling, and can interact with collagen network
what are the 4 steps for pathogen induced upregulation of adhesion?
- bind
- receptor up regulation
- make more receptors
- increased adhesion
true or false: granuloma formation is always a good thing
false, granuloma formation can be both good and bad
what are some factors in bacteria-host surface interactions?
- net surface charge (on host and bacteria)
- surface hydrophobicity (if one cell is phobic and other is philic then bad bonding)
- binding molecules on bacteria and host cell receptors ( ligands and adhesins)
how small does a distance have to be for specific adhesion?
less than 1 nm, anything larger would be nonspecific adhesion (could be van der waals, electrostatic repulsion, and hydrophobic interactions)
What are some traits of nonspecific adhesion?
weak adhering, can allow colonization to surfaces that isnt subject to strong washing force (skin) but not to places with strong washing forces (urinary tract)
what are the aspects of specific adhesion?
on the bacterial surface you have the surface protein (lectins) and on the host cell you have the carbohydrate part of the glycolipid or glycoprotein
where would you find bacterial adhesins on gram negative and positive bacteria? what advantage do they provide?
on gram negative bacteria you would find the proteins on the outer membrane and on gram positive would find it on cell wall. Allow for binding from safe distance
what are the three types of adhesins?
- pili/fimbriae
- non-pilus surface proteins
- polysaccharides
what are some traits of bacterial fimbriae?
multimeric, adhesive appendages protruding many microns out allowing for farther safer connection than surface proteins
what are the consequences of adhesion?
- organism colonizes surface
- pathogen colonizes surface and secretes toxin
- colonize and form a biofilm
what is a biofilm?
a community of microorganisms, associated with a surface, and encased in an extracellular polymeric matrix
what are the types of biofilms?
simple: single species
complex: multiple species, co-aggregation, and polysaccharides trap others
what are the 4 steps for biofilm formation?
- interaction of cells with a surface or with each other
- films aggregate
- cells form an extracellular matrix
- structures differ based on organisms in film and environmental conditions
