Adhesion

Question 1

Types of bacterial adhesions

Answer 1

Mostly proteins, sometimes glycoconjugates or lipoteichnoic acid.

Nonfimbiral adhesin.
P fimbirae.
Type IV pili.
Curli.

Question 2

Characteristics of adhesins

Answer 2

Adheison to host clel surfaces or EZM.
Determines tissue tropism.
Consequences: Colonization, penetration, triggering of host reposnse, uptake into host cell

Question 3

non-fimbrial adhesins

Answer 3

Anchored in bacterial membrane.
Deirect binding to host cell molecule or via bridging.
Gram-pos/neg.

Question 4

P pili (E.coli)

Answer 4

P: pyelonephritis-ass.
Pap operon.
Type II secretion system.
Bind glycolipids.
Host cells: upper urinary tract.

Question 5

Number of adhesins

Answer 5

Bacteria often contain multiple. Often act synergistically. Can be functionally redundent > rarely essential VF

Question 6

Possible adhesin targets

Answer 6

Cadherings
Ig
Selectins
beta1-integrins

Question 7

EPEC/EHEC adherence

Answer 7

Initial binding via type IV pilus. Second adhesin: intimin (adheres to TIR which is translocated via type III secretion system)

Question 8

RGD site

Answer 8

Eukaryotic binding site for integrins.
Arg-Gly-Asp tripeptice.
Some bacterial adhesins mimic RGD site.

Question 9

Example for molecular mimicry

Answer 9

Filmanetous hemagglutinin FHA of Bordetella perfussis.

Nonfimbiral adhesin.

Question 10

FHA binding activities

Answer 10

1. Carbohydrate binding to ciliated cells of resp. tract
2. heparan sulfate binding to EZM on epithelial cells
3. integrin binding via RGD site on phagocytes
   (>molecular mimicry!)

Question 11

Bordetellla pertussis

Answer 11

Replicates on ciliated cells of nasopharyngeal/upper resp. tract.
Whooping cough.
Binds to epithelial cells/monocytes in resp. tract.
Vaccine available.

Question 12

Mycobacterium leprae - tropism?

Answer 12

Obligatory intracellular (T!).
Tropism for Schwann cells: PGL1 binds laminin (laminin receptors on Schwann cells: alpha-dystroglcan and beta4-integrins)

Question 13

Adherence of staphylococci and streptococci

Answer 13

Via host bridging molecule.
Common host molecules: ECM components (eg collagen)
Species-specifity (eg S.aureis > fibrin)

Question 14

Phase variation

Answer 14

Regulated expression of adhesins in response to environmental signals > sequential binding to diff host cell structures.
Immune evasion.

Question 15

Example for phase variation

Answer 15

Neisseria.
Isoforms of Opa (and Opc) protein > interaction with different cells.
> Opa-HS, Opa-CEA, Opc

> > immune evasion

Question 16

Yersinia - penetration

Answer 16

Invasin: nonfimbrial adhesins, bind beta1-integrins.

Zipper-like uptake: phagocytosis by M cells

Question 17

Listeria - penetration

Answer 17

Express interlin A > binds E-cadhering > zipper-like uptake by epithelial cells

Question 18

Plasmodium falciparum - adhesion

Answer 18

Adhesin: PfEMP1
Exported though host cell (erys) > forms knobs > erys adhere to endothelial cells of large (immunevasion) or small blood vessels (occlusion > inflammation)

Question 19

antigenic variation in PfEMP1

Answer 19

Encoded by various genes, only one expressed at a time > can switch > prolonged infections

> > immune evasion

Question 20

Function of UPEC adhesins

Answer 20

P/Type I pili

> pathogen is not washed out

Question 21

General types of binding partners of bacterial adhesins

Answer 21

Cell-surface receptors
ECM proteins
bridging molecules