Exam2Lec6IntrotoVirology

Question 1

What are viruses?

Answer 1

A collection of genetic info (RNA or DNA) inside a protective protein coat

OBLIGATE INTRACELLULAR PATOGEN

Question 2

Viruses cannot do what?

Answer 2

DO NOT encode ribosome

Question 3

Since Viruses cannot encode ribosomes thus:

Answer 3

cannot divide and replicate on their own

needs host cell machinery to replicate

Question 4

What are the 6 virus classifications

Answer 4

genetic content

structure

host range

replication strategy

Disease

Containment level

Question 5

What is genetic content in classification?

Answer 5

DNA vs RNA

Signal stranded (ss) vs Double stranded (ds)

Segmented and non-segmented

Positive sense and negative sense

Question 6

What is structure in classification

Answer 6

Icosahedral vs helical

Enveloped vs. non enveloped

Question 7

What is host range in classification

Answer 7

Which species can be infected by the virus

Tropism: which cells or cell type are infected by the virus

Question 8

What is tropism

Answer 8

which cells or cell type are infected by the virus

Question 9

List out the ICTV classification

Answer 9

order: general genome organization

Family subfamily: genome organization/gene arrangement

genus subspecies:genome organization/size and sequence homologies

Species subspecies : ecological niche

Serotype: antigens

Strain : geography

Isolate

Question 10

What is the typical case of RNA viruses

Answer 10

Usually single stranded genomes

Question 11

what are the two genomes in RNA viruses, explain them

Answer 11

Plus stranded genome
-mRNA sense=translated
***directly translated to make proteins
-mostly isosahedral

Minus stranded genome
- genomic RNA : transcribed to make mRNA
*** templates of RNA so they need to be transcribed first then translated
-ALL helical capsizes

Question 12

Explain + stranded

Answer 12

-mRNA sense=translated
***directly translated to make proteins
-mostly isosahedral

Question 13

Explain - stranded

Answer 13

• genomic RNA : transcribed to make mRNA
  *** templates/compliments of RNA so they need to be transcribed first then translated
  -ALL helical capsizes

Question 14

what is the typical case of DNA viruses genome?

Answer 14

Usually double stranded genomes

DNA virus genomes are linear or circular

Most have icosahedral capsid symmetry

Question 15

Explain non enveloped

Answer 15

Consist of a genome (n.a) surrounded by protein shell (capsids)

VERY STABLE to environment (days to weeks)

Question 16

What are examples of non-enveloped viruses

Answer 16

poliovirus

adenovirus

foot and mouth disease virus

Question 17

Explain enveloped viruses

Answer 17

consist of capsid (nucleocapsid ) surrounded by a lipid bilayer that has viral proteins protruding from it

SENSITIVE to environment (hours to days)

Question 18

example of enveloped virus

Answer 18

Influenza virus

Question 19

Explain icosahedral capsids

Answer 19

Remember usually + stranded

• CLOSED structure with FIXED volume

Subunits self assemble and form stable interacting within clusters

Larger viruses have scaffolding proteins
**keep genome stable as they build

Question 20

Isosahedral capsid a closed or open structure and fixed or variable volume?

Answer 20

Closed and fixed

Question 21

Explain helical capsids

Answer 21

Remember: (-) stranded

Open conformation ie. variable volume

Rodlike or filamentous structures

Generally ENVELOPED VIRUSES (use budding to acquire envelope)

Question 22

Helical capsid a closed or open structure and fixed or variable volume?

Answer 22

open and variable volume

Question 23

Explain helical capsid assembly and budding

Answer 23

1. individual capsomers associate to form disc
2. disc translates to form a LOCKWASHER structure, by stacking on each other forming beginning of helix
3. Viron RNA loop feeds through central hole to continue helix elongation
4. Buds into lipid bilayer of cell

Question 24

Explain stages of replication

Answer 24

Initial infection: virus low but then builds

Local immunity (IFN) are kicked in to kill virus

Then we get symptoms from our reaction to virus

Question 25

Why do we get symptoms from a virus

Answer 25

It is our own immune reaction to the virus causes the symptoms

Question 26

What is an incubation period

Answer 26

time between initial infection and symptoms

Question 27

Acute infection is followed by viral clearance explain this

Answer 27

either localized or disseminated ultimately eradicated ** no more virus left in body

Question 28

What are examples of acute infection flood by viral clearance

Answer 28

colds, rest intections ***rhinoviruses, coronaviruses Variola (smallpox) Influenza

Question 29

Acute infection followed by latent infection

Answer 29

initial infection and apparent clearances viral genomes maintained in specific tissues, cell types Reactivation by physiological response to external stimuli

Question 30

what are virus examples of Acute infection followed by latent infection

Answer 30

HERPES SIMPLEX VIRUS (HVS-1)

Question 31

Explain the acute infection followed by latent infection in HVS-1

Answer 31

initial infection in epithelium (oral tissues) Spread to neurons and maintenance of genomes in cell bodies Reactivation by responses to stress

Question 32

Explain acute infection followed by chronic infection

Answer 32

initial infection and partial clearance persistent infection and production of virus

Question 33

What are example viruses of acute infection followed by chronic infection

Answer 33

HIV and Tumors (cancer)

Question 34

What are the 3 containment levels

Answer 34

Category A, B, C

Question 35

Explain Cat A

Answer 35

Early disseminated or transmitted person to person cause high mortality with the potential for major public health impact might cause public panic and social disruption require special action for public health preparedness

Question 36

What is examples of cat A

Answer 36

smallpox and viral hemorrhagic fevers

Question 37

Explain cat B

Answer 37

moderately easily to disseminate cause moderate morbidity and low mortality rewrite specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance

Question 38

What an example of cat B

Answer 38

encephalitis viruses

Question 39

Explain cat C

Answer 39

readily available easy to produce and disseminate potential for high morbidity and mortality and major health impact

Question 40

what is an example of cat C

Answer 40

emerging viruses

Question 41

What are the containment levels

Answer 41

endemic epidemic pandemic

Question 42

Endemic

Answer 42

continuous transmission within a population ex: flu

Question 43

epidemic

Answer 43

peaks of disease above baseline or expected rate

Question 44

pandemic

Answer 44

worldwide epidemic