intracellular pathogens

Question 1

can only grow inside cells. Usually only able to grow in laboratory in cultured mammalian cells.

Answer 1

Obligate:

Question 2

ability to grow inside or outside of cells. Often observed as the ability to grow on bacteriological medium or grow extracellularly in tissues.

Answer 2

Facultative:

Question 3

Usually intracellular pathogens are cell-tropic: one host cell type targeted

1. Shigella in ______
2. Rickettsia in _______
3. M. tuberculosis in ________

Answer 3

1. Shigella in epithelium
2. Rickettsia in endothelium
3. M. tuberculosis in macrophage

Question 4

why are macrophages a target of pathogens?

Answer 4

1. efficient at phagocytosis
2. killing mechan. bypass
3. manipulation

Question 5

One bacterial group can grow in neutrophils:

Answer 5

Anaplasma (vector borne)

Question 6

why is the intestinal epithelium a barrier to pathogens

Answer 6

1. thick mucous layer
2. microvilli leads to poor surface area
3. adhesion receptors

Question 7

how can pathogens enter tthrough the intestinal epithelium

Answer 7

due to the presence of M cells that have reduced mucous secretion and adhesion receptors are at apical end allowing pathogens to enter and spread

Question 8

There are broadly two different ways that bacterial pathogens trick cells into internalizing them:

Answer 8

1. Receptor-driven (Zippering)

2. Triggering of the host actin cytoskeleton

Question 9

Listeria monocytogenes an oral pathogen associated with contaminated foods, uptake mechanism into non-phagocytic cells

Answer 9

receptor driven- zippering

Question 10

trigger driven uptake into non-phagocytic cells invovles sa specialized secretion system

Answer 10

type III system- salmonella, shigella

Question 11

we have a few ways of fighting or setting traps for intracellular pathogens such as (3)

Answer 11

1. NADPH oxidase releases O2-
2. trafficking to the lysosome
3. Xenophagy- bacteria entering cytoplasm can be ubiquitinated which can be recognized by autophagopores and degraded

Question 12

strategies for intracellular growth

Answer 12

1. within vacuole
2. within cytosol

***in all cases, pathogens must interfere with host killing mechanisms

Question 13

Problem that arise from attempting to grow in an intravacuolar compartment (and solutions)

Answer 13

1. Lysosomal degradation:
   avoid trafficking to lysosome or remodel lysosome.
2. Nutrients:
   access vesicular and cytoplasmic stores through membrane trafficking or vacuolar channels
3. Membrane expansion:
   obtain material from host membrane compartments

Question 14

Pathogens hijack material from a variety of cellular compartments to support intravacuolar growth

Answer 14

yep

Question 15

___________ grows within a rough ER-associated membrane compartment in alveolar macrophages

Answer 15

Legionella pneumophila

Question 16

requires
charcoal, high iron and high
cysteine to grow

Answer 16

Fastidious organism:

Question 17

Growth in amoebae selects for the single most important virulence property of L. pneumophila: the ability to grow in __________

Answer 17

macrophages

Question 18

L pneumophila injects proteins on contact with alveolar
macrophages to initiate formation of replication vacuole

what type of secretion system is this?

Answer 18

injection of proteins occurs via a type IV secretion system

Question 19

treatment of legionella takes into account intracellular locale so Aminoslycosides and B-lactams are ineffective so, these (2) are used

Answer 19

1. macrolides

2. quinolones

Question 20

ricketssi is able to destroy compartment by

Answer 20

hypothetical hemolysin

Question 21

rickettsia grow in cytoplasm so what needs to be blocked?

Answer 21

autophagy

Question 22

how does rickettsia spread cell-to-cell

Answer 22

actin based motility

Question 23

vasculitis seen in rickettsia?

Answer 23

Occasional rupture of endothelial cells may explain pathology of vasculitis