what are primary pathogens ?
causes disease readily in healthy hosts
what are opportunistic pathogens ?
only cause disease when displaced to an unusual site “ wrong place” or when the host has a weakened immune system
what is an example opportunistic pathogens ?
ecoli which is normal in the gut going to urethra and causing a UTI (microbes in the wrong place)
what are the 3 criterias for a normal microbiome in humans ?
- Microbes that reside on or within human tissue
2.Normally do not cause disease - Maybe protect against certain health problems
what methods must pathogens do to cause infection
Enter the host
Attach to and invade specific cells and/or tissue within the host
Evade host defences
Obtain nutrients from the best
Exit the host
and overall cause damage
what are virulence factors and what 3 things must it do to help cause disease
products made by pathogens that enhance their ability to cause disease
1. gain access to tissue/cells
2. evade host defences
3. obtain nutrients
what 3 examples of virulence factors ?
adhesions
capsules
viral attachment proteins
how do virus attach to host cell and become a virulence factor
viral attachment proteins attach to specific host receptors and cause host specificity
how do bacteria pathogens attach to host cells and be a virulence factor?
adhesins are bacterial molecules used for binding and colonizing host tissues
what is an example of adhesions and what are the 3 functions ?
Fimbria with a tip protein that regulates the host cell receptor
1. it can control expression by turning it on and off
2. one bacterium can express different types
3. specific interactions with host receptors
what is the difference between viruses and pathogens in terms of attachment and how are they the same
adhesions are regulatory viral attachment proteins are not
adhesions can also recognizes different types of receptors
they have the same goal as virulence factors
what is example of bacteria making it own receptors for host cell surfaces what does it cause
in the ecoli cell the tir and intimin protein enter the host cell and become a signal and receptor on the surface of microvilli and it creates a pedestal that squishes microvilli and decreases absorption of nutrients and water
what is a capsule role in virulence factor ?
capsules help pathogens avoid phagocytosis which is the engulfing of foreign cells by masking the proteins of the virus
what are the 4 ways a bacteria pathogen will take to obtain iron ?
- make its own iron binding protein called siderophores and take it from binding proteins
- a bacterial transport protein binds direct to the iron and host binding protein and take it to the bacterial cell
- lowering PH to reduce the binding affinity between the iron and host iron binding protein
- using cytolysins to lyse host cell and release iron
what is the difference between and exotoxin endotoxin and what are they used for ?
exotoxin is secreted into the cell and acts directly on the cell and endotoxin is already part of the cell wall structure and triggers inflammatory response
they are both used to obtain nutrients
what are cytotoxins and 2 types of cytoxins ?
they are an exotoxin cytotoxin that lyse cells
hemolysis lyse red blood cells
leukocidins damage/kill white blood cells
what are the 2 mechanisms of cytotoxins and how do they work
- Poreformation where for example s aures makes monomers that bind to a membrane receptor and more bind that lead to a conformational change where the membrane forms a pore where influx and outflux of molecules lead to cell lysis and bacteria consume lead nutrients
- Membrane Degradation ex breaking of the phospholipinds in the membrane
what does each part of the ab toxin do?
the a subunit actually carries the toxic activity and damage host cell
the b subunit binds to cell receptor and determine cell type
what is an example of the AB subunit mechanism ?
in diptheria toxin the AB subunit enter via endocytosis and a pH change seperate the two subunit where subunit A enters the cytoplasm and inhibit protein synthesis which can lead to cell death
what do super antigens do
the are an exotoxin that act on any T cells not specific ones unlike the normal antigen that acts on specific T cell when needed and release the appropriate cytokines , with superantigens binding to any type of T cell it release alot of cytokines causing a inflammatory response in a certain part of the body
how does diphtheria differ from other bacterial toxins ?
it it cause by a bacteria however this bacteria has a certain phage with toxin integrated in bacterial to work (viral)
what is example of an endotoxin and what is it 3 components and what do they do
the gram negative LPS endotoxin is toxic to mammals has its outer membrane with lipopolysaccharides (LPS) and it components of an Lipid A that produces toxic effect and lead to inflammation which causes tissue damage
the o antigen shields host immune responses as they target o antigen
and the core polysaccharide
only gramnegative can be endo
what is the grampostive endotoxin like example
LTA and acid that is in the cell wall and anchored and also leads to inflammation and tissue damage
what do low level vs high levels of LPA vs LPS contribute to
low levels can cause mild symptoms like fever and inflammations whilst higher levels will cause death due to shock and tissue necrosis
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Topic 2 Microbial Ecology17
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Topic 4 Microbial Habitats13
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Topic 4 Clickers + Additional Question8
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Topic 5 Biogeochemical cycling40
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Topic 7: Water Quality32
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Topic 8: Food & Industry21
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addtitional5
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Genetics and Biotechnology31
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Topic 9 Clickers + Additional Question16
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Host-Pathogen Relationships25
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Topic 10 Clickers + Additional Question12
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Immunology0
