Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BI302 > Virology 4 > Flashcards

Virology 4 Flashcards

1
Q

What is the only DNA virus that does not use the nucleus as the site of replication?

A

Pox viruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Baltimore classification of B19 virus?

A

Group 2: Single stranded DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What family does B19 belong to?

A

Paroviridae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are paroviruses?

A

-smallest, simple eukaryotic viruses
-Discovered in the 1960’s.
-Human Parvovirus infections (B19 virus) were only recognized in the 1980’s.
-Since then 50 other parvoviruses have been identified.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Paroviruses can be divided into two groups:

A
  1. Defective viruses which are dependent on helper virus for replication
  2. Autonomous, replication-competent viruses.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

2 subfamilies of Parvovirdae

A

-Parvovirinae (vertebrate hosts)
-Densovirinae (arthropod/inverterbate hosts)
*Both groups contain 3 genuses each

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Subfamily: Parvovirinae

A

-Parvovirus e.g mice minute virus
-Erythrovirus e.g B19 virus
-Dependovirus e.g Adeno-associated virus 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Subfamily: Densovirinae

A

-Densovirus e.g Junonio coenia densovirus
-Iteravirus e.g Bombyx mori densovirus
-Contravirus e.g Aedes aegypti denosovirus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is fifth disease?

A

-A mild rash illness caused by B19 virus
-Also known as erythema infectiosum
-Illness occurs 4-14 days after infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Symptoms of fifths disease:

A

-fever
-runny nose
-headache
-rash known as ‘slapped cheek’ rash
-pain and swollen joint (polyarthropathy syndrome)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is B19 transmitted?

A

Through cough or sneeze
-Person is contagious when it just feels like a cold and before rash and joint swelling. Once the rash appears they are no longer contagious.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Tropism of B19:

A

-Human erythroid progenitor cell
-Foetal liver cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Structure of B19 virus:

A

-Icosahedral capsid
-Non-enveloped
-ssDNA (linear) non segmented
-25nm
-consists only of protein (50%) and DNA (50%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Characteristics of capsid:

A

-2 capsid proteins (VP1, VP2)
-VP1 takes up 5% of the capsid and VP2 takes up 95%
-60 capsomers
-The capsid confers considerable stability on the virions which are resistant to inactivation by pH, solvents or high temperatures (1h @ 50 ° C).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

B19 Genome organization:

A

-Simple organization
-Linear single stranded non segmented DNA genome
-Has structural and structural proteins (VP1,VP2) in between terminal repeats (hairpins).
-VP1 and VP2 are identical except VP1 has a VP1U region (which consists of 229 extra amino acids and is necessary for viral entry)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Disadvantages of studying B19 genome expression:

A

-Difficult to grow in culture (erythrocyte progenitor cells are needed)
-Poorly understood
-Little known of its biology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

B19V replication cycle:

A
  1. Virus binds to receptor and enters the cell
  2. Viral DNA translocates to nucleus
  3. NS and CAP protein are expressed
  4. Viral DNA is replicated
  5. Capsid is assembled
  6. Cell is lysed and new viruses are released.
    (*look at slide 16 for diagram)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

B19 infection causes what:

A

-Loss of red blood cells due to infection of reticulocytes.
-In ~80% patients, there is also arthralgia (temporary arthritis)
-B19 infection in pregnancy can cause miscarriage
-Hydrops fetalis (a condition in which large amounts of fluid build up in a baby’s tissues and organs, causing extensive swelling)
-Aplastic crisis (Reticulocytopenia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Treatment for B19 infection:

A

-No vaccine but can be treated with intravenous immunoglobulin therapy (IVIG)

20
Q

Baltimore Classification for Herpes:

A

Group 1: single stranded DNA

21
Q

What family does herpes belong to?

A

Herpesviridae

22
Q

3 subfamilies of herpesviridae:

A

-Alpha herpesviruses
-Beta herpesviruses
-Gamma herpesviruses

23
Q

Alpha herpesviruses:

A

(HHV-1) (Herpes simplex also known as cold sores)
-HHV-2 (genital herpes);
-HHV3 (Varicella)/Herpes zoster virus (Chickenpox/shingles)
*Side not HHV means human herpes virus

24
Q

Beta herpesviruses:

A

-HHV5 (Human Cytomegalovirus)

25
Q

Gamma herpesviruses:

A

-HHV4 (Epstein Barr Virus)

26
Q

What is latency?

A

It is a quiescent state of viral infection with minimal effect on cell function

27
Q

Structure of HHV1 (Herpes Simplex)

A

-Complex and large (200nm)
-Lipid envelope (10 proteins, gB, gN)
-Tegument (15 proteins)
-Icosahedral nucleocapsid
-Linear ds DNA genome
-Nonlytic (budding)
-gB binds to extracellular matrix proteins

28
Q

Tropism of HHV1:

A

Pantropic but sometimes described as neurotropic

29
Q

What is a tegument?

A

A mixture of 15 enzymes but has no metabolic acitivity

30
Q

HHV1 Genome organization:

A

-Linear double stranded DNA genome
-126kb unique long (Ul) region containing 56 genes
-26kb unique short (Us) region containing 12 genes
-Flanked by terminal repeats and internal intererval repeats
-84 opening reading frames
-3 ori

31
Q

HHV replication cycle step 1:

A
  1. Virus (gB) binds to extracellular matrix
32
Q

HHV replication cycle step 2:

A

2.Tegument proteins corrupt cell function and the Viral core (capsid) goes to nucleus.

33
Q

HHV replication cycle step 3:

A
  1. DNA circularizes and transcribes Immediate Early (IE) & Early (E) mRNAs
34
Q

HHV replication cycle step 4:

A
  1. IE & E proteins induce viral DNA replication
35
Q

HHV replication cycle step 5:

A
  1. mRNA for late proteins are produced. Late proteins transported back to nucleus for capsid assembly
36
Q

HHV replication cycle step 6:

A
  1. Loaded Capsids bud into the Golgi/RER
37
Q

HHV replication cycle step 7:

A
  1. Virus matures in an endocytic vesicle
38
Q

HHV replication cycle step 8:

A
  1. Mature virus released from cell
39
Q

Primary HHV-1 infection:

A

Is usually Inapparent but some symptoms include:
-Mouth ulcers (Mucosal)
-whitlow (skin), or rare more serious forms

40
Q

How can HHV-1 remain persistent:

A

If it is not cleared by the immune system:
-After 1degree infection in buccal mucosa, the infection travels via nerve cells to trigeminal ganglion where it remains latent.
-In some people it reactivates

41
Q

Reactivated HHV-1 infection:

A

-Cold sores
-Uveitis/keratitis (rare)

42
Q

How does HHV-1 become latent:

A
  1. Virus (gb) binds to extracellular matrix
  2. Tegument proteins corrupt cell function, viral core goes to nucleus
  3. DNA circularizes and transcribes LAT mRNA and a small number of LAT proteins.
43
Q

How do Latent neurons become permissive (how does the infection reactivate)

A

A “stress signal” caused by UV rays, other infections or stress

44
Q

Why are neurons more favorable for HHV1 to establish latency on:

A

-Neurons do not divide, which allows the viral genome to avoid complete replication.

45
Q

What is Virion Host shutoff (vhs) protein and where is it located?

A

-A late protein that switches off host protein synthesis and degrades host mRNA
-Located in the tegument and is encoded by UL41 gene

46
Q

Joint function of vhs and ICP47 (immediate early gene)

A

Prevents MHC class I expression on host cells

BI302 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions