adherence and invasion of bacteria

colonizing bacteria are associated or adherent to muscosal surface -> reaction within the host tissue

direct binding site to host cell or bridged binding via a host molecule -> both adhesins

Tissue tropism: bordetella Haemophilus, Pasteurella in the respiratory tract; oral streptococci; Enterobacti in the gut; E.coli strains in the urogenital tranct and the CNS; Haemophilus, pneumococci, meningococci in the CNS

Host tropism: F5-E.coli in calfs; F4 E coli in piglets; Helicobacter pylori in human stomach

pic 9

Pilin = ca 20kDa protein

helical

Tip adhesin

a structure

E. coli:

Typ 1 (F1) - mannose, fibronectin, Plasminogen, CEACAM*

F4 - Gal-Gal

F5 - NeuGe-GM3

F41 - N-Acetylglucosamin

P-Fimbriae* - Gal-Gal, Fibronection

curli-Fimbriae - Fibronectin

Klebsiella:

Typ 3 - complex

pic 14

pic 15

CEACAMs mediate intercellular adhesion through homophilic and/or heterophilic interactions

pic 18

Enteropathogenic e coli - epec

Adhesion methods:

1. adherence (type 4 fimbria)

2. sectretion of effectors

3. intimin-adherence (Protein)

composition of the extracellular matric

• usually glycoproteins

• collagen, fibronectin, etc bind so it can attach to hostcell

pic 23

pic 24

enzymes used for invasion

all produced by bacti

in host = distruction of tissue

“spreddig-factors”

• Superoxide dismutase & catalase => important inside the hostcell

• Formation of fibrin clots formed by coagulation.

• process mediated by thrombin. fibrin forms net skin

• fribrinogen produces by thrombocytes

• break down of fibrin clots by coagulation

• streptokinase C and D in complex with plasmin -> ability to funciton => bacti can escape the clot, Break-down of fibrin clots formed by colaboration

Streptococcsi

s. aureus: examination of hyaluronidase activity using s.equi, ssp equi

Hyaluronidas and bacteria degrade cells

obligate intracellular bacteria…can not reproduce outside their host cells because their metabolism relies on host molecules

facultative intracellulat bacteria…are capable of living and reproducing either inside or outside cells. -> prefer to live inside the host cell bc of advantages

• protection againt recognition by immune system (phagocytes, complement system, ABs)

• partial protection against ABs

• Nutrient rich habitat

• overcome of barriers: Possibility to spread into deeper tissue

• dissemination: spread into bloodstream (systemic dissemination by lympho-hematogenous spreading)

Chlamydia, chlamydophila - sexually transmitted, psittacosis and ornithosis

rickettsia, coxiella - vector-born disease, Q-fever in humans and animals

Lawsonia - Diarrhea in pigs (proliferative Enteropathie)

1. “zipper” mechanism -> listeria & Yersinia

mycobacteria - tuberculosis in humans and animals, paratuberculosis in ruminants

salmonella - salmonellosis

yersinia - bowel disease

shigella - bowel disease

brucella - brucellosis

bartonella - cat scratch disease, bacterial angiomatosis, peliosis, hepatitis, endocarditis

listeria - listeriosis

1. “zipper” mechanism

2. “trigger” mechanism (membrane ruffling)

3. “Caveolae”-mediated uptake

• sec-independent

• secretion of toxins, proteases, lipases

• secretion directly from the cytoplasmic space into the surrounding medium

• no periplasmic intermediate

• C-terminal signal sequence, ca 60AS

• 3 components:

  • ABC transporter

  • membrane fusion protein

  • outer membrane protein

• e.g. a-hemolysin/E.coli

• dependent on ATPase

1. step sec-dependent

2. substrate: extracellulare enzymes and toxins (gram- bacti)

3. e.g. choleratoxin

some bacti are using it to detect toxins

• sec-independent

• similar to flagellar assembly

• needle lke structure like the flagella

• EM reconstructions of basal body of the flagellum & typ 3 injectisome of salmonella

injection of bacterial effector proteins directly into eucaryotic host cell or into the surrounding medium

• translocation of Toxins and of DNA

• sec-dependent and independent

• homlogous to bacterial conjugation machinery

• translocation of bacterial proteins into eukrayotic cells

toxin delivery - killing of gram- bacti

DNA release - biofilminformation of neissieria (release of ssDNA)

DNA uptake - helicobacter uptake of ddDNA and/or dsDNA

conjugation - gram+ and gram- bacti (dsDNA (circular) with red dot goes to recipient -> ssDNA (ciruclar) with dot in it)

injection of effector protein -> Helicobacter, Bartonella, Anaplasma, Ehrlichia

Toxin secretion -> Bordetella

Gene transfer to host cell ->agrobacterium, bartonella

non-lytic release from protozoan cell -> legionella

intracellular survival of pathogen -> legionella, coxiella, bartonella, brucella, rickettsia

intracellular survival of symbionts -> wollbachia, mesorhizobium

Caveosom formation