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SMS Week 4 > Introduction to Virology > Flashcards

Flashcards in Introduction to Virology Deck (43):
1

What are 3 general ways you can classify a virus?


1. on it's genome structure

2. general structural characteristics (enveloped/ shape?)

3. Infection characteristics - the disease it causes and how it causes it

2

Wha tis the final taxonomic classification of viruses?


the genome sequence

3

What is the capsid? What is the nucleocapsid?


the capsid is a protein shell that surrounds the genome of a virus particle

the nucleocapsid is the capsid complexed with the nucleic acid of the virion

4


What is the capsid composed of?


protein subunits called capsomere

5

What lies between the envelope and the capsid in an enveloped virus?


the integument (not all)

6

What are the two main shapes of capsids?


helical (rod-shaped viruses)

icosahedral (spherical viruses  - this is the most efficient arrangements of subunits in a closed shell)

7

Give details about the measles virus...

genome (group)

segmented?

shape?

enveloped?

 

ssRNA - (group 5)

nonsegmented

helical nucleocapsid

enveloped

 

(paramyxoviridae, morbillivirus)

8

Provide details about the Coxsackievirus B...

genome (group)

segmented?

capsid shape?

enveloped?

 

ssRNA +
 (group 4)

Nonsegmented

icosahedral nucleocapsid

nonenveloped

(picornaviridae, enterovirus)

9

What are the two characteristics of a virus that the baltimore classification system takes into account?


the type of nucleic acid it uses

the steps the nucleic acid takes to be replicated

10


What are the 3 classes of DNA viruses?


1. 2. and 7.

1 - dsdNA with classical semiconservative replication

2 - ssDNA + with classical semiconservative replication, but you discard the negative strand when packaging

7 - dsDNA, but the mRNA is used as a template for reverse transcriptase to make genome copies to be packaged

11

What do class 3 viruses have?


dsRNA

transcription of the minus strand gives mRNA for proteins

12

What do class 4 viruses have?


ssRNA +

where the ssRNA+ is used directly for mRNA to translate proteins.

13

What do class 5 viruses have?


ssRNA -

transcribe the minus strand to make mRNA

 

14

What do class 6 viruses have?


they're the retroviruses!

they have ssRNA + that is reverse transcribed to a dsDNA intermediate

the minu strand is then transcribed to make mRNA

15

What determines the tropism for the virus?


what cells have the appropriate receptors the virus needs to bind and enter

16

What are the 5 general steps in a viral infection?


after exposure....

1. attachment

2. penetration and absorption

3. synthesis

4. assembly

5. release

and then it continues in secondary infeections...

 

or you can do it this way...

1. pathogen exposure to mucosal surface

2. invasion

3. primary replication/imune reponse

4. dissemination

5. secondary infections

5. secondary replication and immune response

6. tissue destructoin

7. shedding

17

What does HPV cause?


warts and carcinoma

18

What are the characteristics of HPV?

genome/group

arrangement of genome

capsid shape?

enveloped?


dsDNA (group 1)

circular genome

icosahedral

nonenveloped

(papovaviridae, papillomavirus)

19

How does HPV get the host cell to replicate?

It has two proteins - E6 and E7 - that will block p53 and Rb. Both of these would normally keep an infectec cell from entering S phase, but without them the cell will enter uncontrolled proliferation resulting in warts and carcinoma

20

Describe the progression of HPV through the skin layers.


It enters the skin through a foriegn body or a microabrasion

In the lysogenic state it will infect basal cells and transform them using E6 and E7

In the lytic cycle the virus will either infeect the upper keratinized epithelium or it will just progress with the basal cell from below as it rises and differentiates

In the keratinized layer the virus is able to replicate its DNA and assemble new virions

21

How does one diagnose HPV?


1% acetic acid will turn lesions white in colposcopy

you can then biopsy the white lesions or use PCR

22

What strains of HPV does gardasil protect against?


6, 11, 16, and 18

23

WHat are the general characteristics of poxviruses?


genome/group/arrangment

nucleocapsid?

envelope?

dsDNA (group 1)

linear genome

complex nucleocapsid

enveloped

24

What is special about transmission of poxviruses?


can be zoonotic - form animals

25

What does a complex nucleocapsid look like?


it's more of a barbell shape

26


What are the 3 poxviruses we talk about?


molluscipoxvirus (mulluscum contagiosum)

orthpoxvirus (smallpox)

parapoxvirus (orf virus)

27


What are the 4 herpesviruses we're interested in?


1. herpes simplex (HSV 1 and HSV2)

2. Herpes varicella (chicken pox)

3. Cytomegalovirus (CMV)

4. Lymphocyrptovirus (EBV)

28

How are herpesviruses classified within the group?


alpha, beta, or gamma depending on where they survive in latency...

alpha - in nerve cells (varicella and HSV)

beta - in macrophages (CMV)

gamma - in B cells (EBV)

29

What are the general characteristics of herpesviruses?

genome/group/arrangement?

shape?

enveloped?


dsDNA (group 1)

linear

icosahedral

enveloped

30

What does parvovirus B19 cause?


Fifth disease - erythema infectiosum

also aplastic crisis (infection gets into bone marrow and kills precursor cells)

31

WHat are the characteristics of parvovirus?

genome/group/arrangement

shape?

enveloped?


ssDNA (group 2)

linear genome

icosahedral

nonenveloped

(parvoviridae, erythrovirus)

32

Parvovirus is a biphasic disease, meaning...


has 2 phases...

1st phase: flue like symptoms with viral shedding during viremia

2nd phase: rash, arthralgia and arthritis. aplastic crisis

33

What are the characteristics of picornaviruses?

genome?

segmented?

shape?

envelope?


ssRNA + (group 4)

nonsegmented

icosahedral

nonenveloped

(picornaviridae, enterovirus)

34

What are the 5 picorna viruses we talk about?


1. poliovirus

2. coxsackievirus A and B

3. Echovirus

4. Rhinovirus

5. Enterovirus

35

How are picornaviruses usually transmitted? What's the exception?


usually fecal-oral except the rhinoviruses which are respiratory droplets

36

What are the characteristics of the measles virus (rubeola)?

genome/group

segmented

shape

enveloped?


ssRNA - (Group 5)

nonsegmented

helical

enveloped

(paramyxoviridae, morbillivirus)

37

What is the pathogenicity of measles?q


1. infects epithelial cells of respiratory tract

2. spreads in lymphocytes and by viremia

3. replicates in conjunctiva, respiratory tract, urinary tract, lymphatics, blood vessels and CNS


4. T cell-response to the virus infected capillary endothelial cells causes the rash! (diffuse morbiliform)

 

complications: otisi media, croup, bronchopneumonia, encephalitis, SSPE

38


What are the characteristics of rubella (german measles)?

geome/group

semented?

icosaheral

enveloped?


ssRNA + (group 4)

nosemgneted

icosahedral

enveloped

(togavirus, rubivirus)

39

What do you get with a rubella infection?


robeola - a rash

40

What are the characteristics of flaviviruses?

genome, group

segmented?

shape?

envelope?


ssRNA + (group 4)
nonsegmented

icosahedral

enveloped

41

What are the two types of flaviviruses w talk about?


dengue fever and west nile

42

How are flaviviruses transmitted?


moquitoes

43