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Virology > Exam III: Lecture 11 > Flashcards

Exam III: Lecture 11 Flashcards

1
Q

There are over ___ kinds of herpesvirus, all infecting vertebrates

A

100

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2
Q

What is the genome of herpesvirus? Type, length, how many encoded proteins, episome, shape of nucleocapsid

A 
ds DNA (120-230 kb)
Linear
30 encoded proteins + cellular proteins
Episome exists outside of the chromosome
Icosahedral nucleocapsid
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3
Q

HV has a wide host range (amphibians, birds, mammals), but each virus restricts itself to how many hosts?

A

one

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4
Q

Is HV a new or old virus?

A

Ancient and co-evolved with their hosts

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5
Q

What are the 3 classes of HV?

A
  1. alpha
  2. beta
  3. gamma
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6
Q

AlphaHV: host range, pace of reproductive cycle, latent in what cells, lytic in what cells

A

Broad host range
Quick reproductive cycle
Latent in sensory ganglia Lytic infection in epideral cells

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7
Q

betaHV: host range, pace of reproductive cycle, latent in what cells, what do infected cells look like?

A

Restricted host range
Long infection cycle
Latent in secretory cells, lymphoreticular cells, kidney cells
Infected cells become enlarged (cytomegaly)

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8
Q

What is an example of a alphaHV?

A

Vericella Zostar Virus (VZV) > chicken pox

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9
Q

What is an example of a betaHV?

A

Cytomegalovirus

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10
Q

gammaHV; host range, pace of reproductive cycle, infection occurs in what cells

A

Restricted host range
Infect lymphoblastoid cells, B cell, T cells
Infection is frequently latent

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11
Q

What is an example of gammaHV?

A

Epstein-bar Virus

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12
Q

What is the cause of 90% of all genital herpes cases in the US?

A

HSV-2

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13
Q

New infections of HSV-2 occur at what rate?

A

1 million new cases/year

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14
Q

The majority of HSV-2 infections are unrecognized, undiagnosed, and untreated

A

True

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15
Q

What is the only herpes virus to spread via coughing/sneezing?

A

Chickenpox = VZV

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16
Q

When do symptoms of chickenpox (VZV) develop?

A

10-21 days after contact with an infected person

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17
Q

VZV infects what?

A

The skin or mucosa of the respiratory tract and progresses through the blood and lymphatic system to the cells of the reticulo-endothelial system

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18
Q

What is a unique feature about Herpesviridae genome structure? (2)

A

Is highly conserved (shows it stemmed from one ancestor and then adapted)
Has repeat regions (A, A’)

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19
Q

HSV entry

A

HSV binds to heparan sulfate and TNFR superfamily member 14

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20
Q

Talk me through HSV-I lifecycle

A

HSV-I > binds to heparan sulfate > enters cell > viral particle nuclear membrane > releases genome + VP16 (VP16 = TF > Imediate early genes/alphagenes = TF > Early genes/betagenes > gamma/Late genes) > genome circularizes > genome replication occurs > genome is produced linearly

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21
Q

Why is having IE > E > L genes advantageous to us?

A

There are multiple points of regulation is HSV

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22
Q

HSV DNA replication uses the rolling circle mechanism

A

True

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23
Q

Tell me about rolling circle replication

A

Seperate the two strands > primers > DNA polymerase > daughter strand gets pushed out of genome = new strand is linear
BUT there is no stop code so the daughter strand is actually multiple copies long = concatimer > concatimer must be cleaved

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24
Q

Tell me about latent infection of HSV-I

A

HSV-I infects nerve cell (lytic infection is inhibited in nerve cells) > retrograde transport to axon > nucleus > goes quiet > produces only latent associated trascripts (regulatory RNAase) > trigger > virus expresses genes > back to synapse > bud out of synapse > infect epithelial cells > lytic infection > spread

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25
Q

Tell me about HSV-I egress?

A

genome reassembles in nucleus > buds out of nucleus = takes part of the nuclear membrane > fuses with perinuclear membrane > spits out nakes viurs > through the golgi membrane > goes to surface of cell > buds out/2 adjacent cells fuse

26
Q

5-10 copies of the viral DNA in the form of __________ stay in the sensory ganglia

A

Circular episomes

27
Q

Reactivation of HSV in neurons can cause what?

A

Nerve pain

28
Q

What are possible triggers for HSV?

A
  1. Fever
  2. Menstruation
  3. UV
  4. Stress
29
Q

What is the physical sign HSV has been reactivated?

A

Cold sore on lip = at the end of the nerve in the face = where HSV buds out

30
Q

What happened in the case of the man with the crazy rash on his face?

A

HSV budded out along the axon instead of just at the synapse

31
Q

What is Acyclovir? Which herpesviruses does it treat?

A

Guanosien analog

Treats HSV-I, HSV-II, VZV

32
Q

What type of genome does Adenovirus have? # bp? Enveloped?

A

dsDNA
35,000-40,000 bp
linear
non-enveloped

33
Q

Where/when was adenovirus first isolated?

A

1953

Military recruits

34
Q

How many serotypes of adenovirus infect humans? What is the implication of this?

A

51

You can get infected over and over and over again

35
Q

What makes a virus a different serotype?

A

If it resists neutralization by antibodies against another serotype

36
Q

Human adenoviruses can cause tumors in rodents; what is the mechanism of cell cycle deregulation?

A

E1A and E1B

37
Q

Talk me through the viral attachment and penetration of adenovirus

A

Adenovirus binds to CAR (coxsackievirus adenovirus receptor) > binds to secondary receptor integrins > receptor-mediated endocytosis

38
Q

What is a unique feature about the viral genome of adenovirus?

A

It has a terminal protein (TP) that sticks out from a penton base = linked covalently to the 5’ end
The virus comes with a protein attached to the genome

39
Q

How many genes does the adenovirus virion encode for? How many proteins does adenovirus encode for?

A

11 genes
Huge number!
With 35,000-40,000 bp and splicing you have tons of isoforms of those proteins

40
Q

Is VA RNA of adenovirus tranlated?

A

No

41
Q

Adenoviral genome is transcribed by ____

A

RNA pol II

42
Q

What are the 5 early promoters seen in adenoviral genome? What do they do?

A
  1. E1A (transactivator of gene expression & oncogenes that activate S phase)
  2. E1B (transactivator of gene expression & oncogenes that activate S phase)
  3. E2 (viral replication)
  4. E3 (modulates host response by blocking MHC maturation)
  5. E4 (transription and replication)
43
Q

What does E1A promote? inhibit?

A

Promotes p53 by sequestering PI4Arf = binds MDM2 > p53 is stabalized&raquo_space; phagocytosis and viral entry into macrophages
Inhibits Rb

44
Q

What does E1B suppress?

A

Apoptosis

45
Q

E1A stimulates the cell cycle and apoptosis, E1B inhibits apoptosis. How would this affect the virus life cycle?

A

Perhaps E1B comes first or is in full force while the virus replicates and then E1A promotes apoptosis and cell cycle in order to escape from the cell

46
Q

Talk me through Adenoviral DNA replication

A

Replicaton begins at an OH group provided by the preterminal protein (PTP) > genom is attached to PTP > 2 strands seperated by ssDBP > DNA polymerase binds to 5’ end with OH group > extends off OH and protein gets incorporated > circularizes > PTP gets cleaved to form TP > second strand gets replicated > end with 2 linear strands with TP

47
Q

Parvovirus genome: how many kb? neg or pos? shape?

A

ssDNA
5 kb
usually, neg strang
icosahedral

48
Q

Parvovirus a member of what genus? What is unique about this genus?

A

Dependovirus

Can only replicate in cells that are infected by adenovirus or herpesvirus

49
Q

More than ___% of humans have antibodies against dependoviruses

A

90

50
Q

What are Adeno-associated viruses?

A

AAV needs a helper vris to replicate

AAV is a dependovirus

51
Q

In the absence of a helper, what does AAV do?

A

Establish a latent infection in chromosome 19 using Rep 78/68 in low levels > upon infection of the cell by adenovirus/herpesvirus the AAV reactivates

52
Q

Why might AAV be beneficial?

A

Gets activated in cancer cells > causes lytic infection > cell death = protects against the formation of tumors

53
Q

Does AAV cause disease?

A

No

54
Q

How does adenovirus cause the reactivation of AAV? (be specific)

A

Adenovirus protiens (E1A, E1B, E4) > transactivate the Rep proteins Rep 78/68 > replication of viral genome

55
Q

What are the two classes of genes in an AAV?

A
  1. Replicase (Rep 78/68/52/40)

2. Structural proteins (VP1, VP2, VP3)

56
Q

Talk me through the replication of viral genome of AAV

A

The ssDNA folds into a hairpin > there is an exposed OH group which serves as the starting point > goes until the other end > hairpin part unwinds > finish up > then there is a cleavage on the other end of the hairpin revealing an OH group > serves as the start to replication > end up with a hybrid genome

57
Q

Parvovirus B19 belongs to what genus? Infects what cells? What pathology does it cause?

A

Erythrovirus
Infects human erythroid cells
‘Slapped Cheek’, joint inflammation, can induce abortion

58
Q

Parvovirus B19 is ____ leading to death of the infected cell

A

Cytolytic

59
Q

Over ___% of adults have antibodies against Parvovirus B19

A

50

60
Q

What is Parvovirus B19 AKA?

A

5th disease

Virology (22 decks)

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