Types of Pathogens

Question 1

what are pathogens?

Answer 1

anything that can cause pathology (could be a bullet), but generally cosnidered biological agents

Question 2

give 6 examples of pathogens

Answer 2

1. viruses
2. bacteria
3. prions
4. protozoans
5. helminths (worms)
6. fungi

Question 3

what are prions?

Answer 3

infective proteins

Question 4

how do prions become prions?

Answer 4

they are normal proteins your cells make, but become misshapen due to improper folding

Question 5

what do “bad proteins,” prions do?

Answer 5

can bind to normal prions and cause them to be misfolded as well

Question 6

what does bad prions binding to good prions cause?

Answer 6

bundles of bad proteins that adhere to each other causing fibrils to form

Question 7

what do fibrils around bundles of bad prions do?

Answer 7

continue to grow to become plaques in neural tissues

Question 8

how is scrapies caused?

Answer 8

from animal-based protein in sheep feed

Question 9

what gene actually codes for prions?

Answer 9

PRNP: not an inherited gene though

Question 10

what are viruses?

Answer 10

protein shells that contain DNA or RNA as their nuclear material (which codes for genes)

Question 11

how do viruses get into cells?

Answer 11

protein receptors on the surface of virus particles bind with specific host cell surface receptors, which serve as the key admitting the virus into the cell

Question 12

what do viruses require to replicate (2)

Answer 12

1. a host cell
2. the host cell’s transcription and translation machinery

Question 13

what happens once a virus has replicated inside a cell?

Answer 13

the virus lyses the cell to release new virions which go one to infect other cells

Question 14

do antibiotics work on viruses? what do you need to treat them?

Answer 14

nope; need antivirals

Question 15

are antivirals useful?

Answer 15

not really because they cost so much to make and viruses mutate so fast anyway they are rendered useless pretty quick

Question 16

what do we usually use against viruses and why?

Answer 16

vaccines because we can make variations as viral pathogenicity changes and viruses are pretty easy to culture in lab

Question 17

what drove antiviral reseaarch and how are the drugs developed for it used?

Answer 17

HIV; antivirals for this usually used in combination

Question 18

how are viruses classified? why?

Answer 18

by the system they infect because they are usually cell specific

Question 19

how does pathogenicity affect viruses?

Answer 19

the more pathogenic a virus is, the quicker it moves through a population until members of that population either develop immunity or death

Question 20

what is the red queen hypothesis?

Answer 20

humans are evolving more complex immunity to outsmart pathogens, which then evolve themselves to infect hosts; this leads to a co-evolutionary arms race but pathogens can evolve more quickly because simpler

Question 21

what are bacteria?

Answer 21

the smallest pathogens considered to be living

Question 22

what kind of karyote aare bacteria? what does this mean?

Answer 22

prokaryotes, no nucleus but use the same DNA that eukaryotes do

Question 23

can bacteria replicate on their own? what do they need?

Answer 23

yes, just need nutrients and warmth

Question 24

how do we treat bacterial infections?

Answer 24

will respond to antibiotics, just need to match for susceptibility

Question 25

how are most antibiotics made?

Answer 25

from nature, that other bacteria made to kill the competition

Question 26

what are many bacterial infections secondary to?

Answer 26

viral infections or cute/injury as bacteria take advantage of weakened immunity

Question 27

what are protozoans?

Answer 27

eukaryotes with a complicated genome in a ture nucleus that are closely related to human DNA

Question 28

how do we treat protozoal infections?

Answer 28

drugs are difficult since genome is so close to us, but lots of protozoans have symbiotic bacteria inside so we can kill that bacteria to kill the protozoan sometimes

Question 29

describe protozoal infections compareed to bacterial and viral

Answer 29

tend to be more chronic and long term because many protozoans have complex lifecycles and employ elaborate immune-evasion mechanisms

Question 30

give 8 examples of protozoan diseases

Answer 30

1. toxoplasmosis
2. amoebic dysentery
3. primary amoebic meningitis
4. scours in calve (zoonotic)
5. giardia
6. leishmania
7. african sleeping sickness
8. chagas disease

Question 31

what are helminths? give two types

Answer 31

parasitic worms; paltyhelminths (flatworms) and nematodes (geohelminths)

Question 32

how long can the disease state from helminths last and why?

Answer 32

can last for many years due to the long life span of the worms in the body

Question 33

how do helminths evade treatment?

Answer 33

employ elaborate immune-evasion mechanisms

Question 34

list and describe 2 immune-evasion mechansism employed by helminths

Answer 34

1. production of cytokine-like molecules to calm immune response
2. molecular mimicry: worms make huma-like proteins to fool the immune system

Question 35

what are the 2 common routes of transmission of helminths?

Answer 35

1. fecal-oral
2. boring through skin

Question 36

what do helminth life cycles usually require?

Answer 36

2 hosts: one invertebrate and one vertebrate

Question 37

what 2 things are true of helminths who remain in bodues for longer?

Answer 37

the longer the pathogen wants to remain in the body:
1. the greater the immune-evasion mechanisms have to be
2. the less pathology the pathogen seeks to cause (typically)

Question 38

describe the length of infections by the 4 types of pathogens

Answer 38

1. viral infections typically run their course rapidly and resolve
2. bacterial infections typically resolve rapidly if treated, if not treated it is up to the immune system to deal with it but drug resistance and genetic recombination can complicate drug therapy
3. protists can become chronic, with relapses occurring if host is immune-suppressed
4. parasitic worms may be with you for many years (10-20)

Question 39

as an epidemiologist, what do you need to know about your pathogen?

Answer 39

1. all that you can
2. especially ALL routes of transmission