Lecture 44 - Viral zoonosis

Question 1

Define:

cross-species transmission

Answer 1

passage of virus between hosts belonging to different species

Question 2

T/F: cross-species transmission and spillover are the same

Answer 2

TRUE

Question 3

Define:

zoonosis

Answer 3

transmission of virus from animals to humans

Question 4

what is a reservoir host

Answer 4

wild vertebrae animal that disease lives in

Question 5

what is an intermediate host

Answer 5

wild or domesticated vertebrae animals

Question 6

what are vector hosts

Answer 6

biting arthropod animals

Question 7

describe a stable host-virus interaction

Answer 7

maintains virus in ecosystem

Question 8

describe an evolving host-virus interaction

Answer 8

passage of virus to a population that has not seen that virus before

Question 9

describe a dead-end host-virus interaction

Answer 9

one way passage of virus to different species; usually means killing host to end virus

Question 10

describe a resistant host-virus interaction

Answer 10

infection is blocked

Question 11

why are there no listed examples of resistant host-virus interactions for spillover

Answer 11

if an interaction is resistant, infection is blocked and thus nothing can be documented

Question 12

define one health

Answer 12

idea that health of people is connected to the health of animals and our shared environment

Question 13

what 5 factors contribute to virus spillover

Answer 13

1. predator-prey interactions
2. bats
3. mosquito vectors
4. forced species interactions
5. ecological and anthropogenic activities

Question 14

summarize predator-prey interactions and their contribution to spillover

Answer 14

contact with bodily fluid in wounds, inhalation, or ingestion and failure of predator immune barriers

ex: SIV, HIV

Question 15

T/F: bats harbor more zoonotic viruses than any other species

Answer 15

TRUE

Question 16

why are bats good reservoir species

Answer 16

they have a constitutively active antiviral response to suppress viruses that allows them to replicate rapidly without killing host

Question 17

what 3 host defenses do bats have

Answer 17

1. constitutive expression of interferons
2. increased expression of heat-shock proteins
3. increased autophagy

Question 18

what 2 immune tolerances do bats have

Answer 18

1. suppressed pathogen sensing
2. suppressed inflammasome pathways

Question 19

what are arboviruses spread by

Answer 19

by vector insects

Question 20

what are the 3 transmission modes of arboviruses

Answer 20

1. urban epidemic cycle (human-vector-human)
2. enzootic cycle (direct spillover from natural hosts)
3. epizootic cycle (amplification in domestic animals)

Question 21

what is a wet market? what are the zoonotic implications?

Answer 21

market where animals are slaughtered upon order; spillover is common due to housing and sanitation

Question 22

T/F: exotic animal trade can also lead to virus spillover

Answer 22

TRUE

Question 23

what are ecological examples that may cause spillover

Answer 23

drought, fire, hurricane

Question 24

what are anthropogenic examples that may cause spillover

Answer 24

urbanization, air travel, pollution, transport of animals