Lecture 6

Question 1

How does evolution happen?

Answer 1

1. A mutation forms within a population
2. Selection for the most fit phenotype

Question 2

True or false: Viruses causes mutation in a population

Answer 2

False
Mutation already existed in population, it was just selected by virus

Question 3

What is the arms race?

Answer 3

Host and virus need to constantly change to survive
-cant stay in the same place

Question 4

What is zoonosis?

Answer 4

Transmission of a pathogen into human pop from another species

Question 5

Why are all the pandemic viruses in humans zoonotic?

Answer 5

Humans cannot defend against viruses from other species since we have not been co-evolving with them
-immune system is not equipped to handle it

Question 6

Name an specific example of cross-species transmission

Answer 6

HIV
-jumped from monkeys to humans

Question 7

How did the HIV pandemic happen?

Answer 7

TRIM5alpha is not suited to block infection against HIV since it came from a diff species and did not co-evolve with it

Question 8

What has evolved on the virus to prevent human Trim5alpha from working?

Answer 8

The capsid protein on the virus

Question 9

How do viruses have such high diversity in genome?

Answer 9

They have a high mutation rate

Question 10

What is the optimal viral mutation rate for viruses and humans?

Answer 10

-Viruses: 2 or no more than 3 –>will not replicate
-Humans: 1

Question 11

What is a quasispecies

Answer 11

-population of evolved viruses
-viruses exist as quasispecies to adapt and help each other
-lots of diversity some are virulent others are not

Question 12

How do humans create a diverse genetic pool?

Answer 12

Single nucleotide polymorphisms (SNPs) can cause mutations and be selected for them

Question 13

Example of mutation in humans? And why would this mutation be in the human pop?

Answer 13

Sickle cell anemia
-those w/ homo allele have sickle cell anemia
-even though it is bad, it has selection against malaria

Question 14

Name 5 emerging viruses

Answer 14

1. SARS-COV 2
2. HIV
3. Pandemic flu
4. Ebola
5. Zika

Question 15

What needs to happen in transmission for it to be a pandemic virus?

Answer 15

Spillover and SUSTAINED human transmission

Question 16

True or false: Every human pandemic virus has originated in another species?

Answer 16

TRUE

Question 17

What is spillover?

Answer 17

Animal to human (zoonotic) transmission

Question 18

What kinds of viruses don’t spread human to human and example?

Answer 18

Zoonotic viruses
-animal–>human–>stop
-Rabies, MERS, bird flu

Question 19

What kinds of viruses spread animal to human to human and example?

Answer 19

Pandemic viruses
-sustained human transmission
-SARS-COV2, HIV, swine flu

Question 20

What kinds of viruses spread human to human only and example?

Answer 20

Human specific viruses
-Herpesviruses, seasonal coronavirus and flu

Question 21

True or false: Probability of a zoonotic jump is not proportional to frequency of contact

Answer 21

FALSE
-Probability of a zoonotic jump is proportional to frequency of contact
-the more we come into contact w/ a species the more likely it is to jump

Question 22

True or false: Probability of zoonotic jump is inversely proportional to phylogenetic distance

Answer 22

TRUE
-more likely to get a virus from a species that is more similar to us because we have similar machinery

Question 23

What are the 2 big molecular barriers that drive evolution in host and virus?

Answer 23

1. Adaptation to entry receptor–>if virus cant get in then non infection
2. Adaptation to overcome cell intrinsic immune factors

Question 24

What can increase the probability of transmission?

Answer 24

-Insects–>mosquitos
-Intermediate/amplifying hosts

Question 25

Examples of insect borne viruses

Answer 25

-West nile
-Dengue

Question 26

Examples of intermediate/amplifying host transmission

Answer 26

-HIV
-SARS
-Pandemic flu

Question 27

What factors facilitate emergence?

Answer 27

1. Population growth
2. Human expansion into animal territory
3. Global traveling/trading
4. IV drug. use and sex trafficking
5. Lots of immunocompromised individuals