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Foundations- Block 1 > Pathology: Viruses > Flashcards

Pathology: Viruses Flashcards

1
Q

What defines a virus?

A

Acellular; no organelles (relies on host cell for replication)

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2
Q

What are the structural components of viruses?

A

Capsid (protein component); genome; envelope surrounding capsid (in some viruses that is a lipid bilayer)

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3
Q

What is the genome of a virus?

A
  • ssDNA or dsDNA
  • circular, ss, or ds
  • ssRNA or dsRNA
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4
Q

What are the capsid shapes in viruses?

A
  • Icosahedral
  • Helical
  • Complex
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5
Q

What are the general steps in the viral replication cycle?

A

Attachment -> Entry-> uncoating -> viral gene expression (via transcription and/or translation) -> genome replication -> assembly -> maturation and egress

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6
Q

Where in the replication cycle is the most infectious viruses? Least?

A

Most: assembly and maturation

Least: eclipse (while reproducing)

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7
Q

How are viruses classified?

A
  • nucleic acid genome
  • shape/structure
  • replication strategy
  • disease type
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8
Q

What are the consequences of viral infections in cells?

A

Lytic infection

Syncytium formation

Hyperplasia

Transformation

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9
Q

Rhinovirus does what to the nasopharyngeal cavities?

A

Causes lytic infections in the upper respiratory tract

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10
Q

Syncytia formation of viruses happens only with ______ type of virus.

A

Envelope viruses (HIV is an example)

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11
Q

What does syncytia formation do? How does the immune system react?

A

Ingrains glycoproteins in the host cell wall that binds them to surrounding cells (syncytia is the fused clump of cells)

-immune system atacc this

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12
Q

Epstein Barr virus and the Papilloma virus cause what type of cell change?

A

Hyperplasia (especially in cells that should not be replicating)

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13
Q

What is transformation caused by viral infection?

A

Transformation of regular cells causing true cancer (HTLV is the only known virus that directly causes cancer)

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14
Q

What is the initial clinical presentation of viral infections?

A

Asymptomatic

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15
Q

What causes acute diseases from viral infection?

A

Viral replication

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16
Q

What are latent or persistent infections?

A

Like herpes: has “down time” of replication, then gets activated again, replicates, then infection shows

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17
Q

What are the DNA containing virus families?

A
  • parvoviridae (smallest)
  • Polyomaviridae
  • Papillomaviridae
  • Adenoviridae
  • Hepadnaviridae
  • Herpesviridae
  • Poxyviridae (largest)
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18
Q

What enzyme does a DNA Virus need? Where does it replicate if it does not have one? What do most DNA cells use?

A

DNA and RNA polymerase; nucleus

-MOST viruses use the host’s DNA/RNA polymerases

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19
Q

What is the target of many antivirals of DNA viruses?

A

Virus-endogenous DNA polymerase

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20
Q

What kind of DNA does parvoviridae have? Where does it replicate? Does it have its own enzyme? Where does p. B19 replicate?

A
  • ssDNA
  • In replicating host cell’s nucleus
  • No it doesnt
  • RBC to cause fifth disease and fetal death
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21
Q

What kind of DNA does polyomaviridae have? What is the speed of its replication cycle? Does it have its own enzymes?

A

Circular dsDNA

  • slow replication
  • uses cell’s enzymes to replicate
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22
Q

What family does JC Virus belong to? What does it cause?

A

Polyoma virus

Progressive multifocal leukoencephalopathy

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23
Q

What family does the BK virus belong to? What does it cause?

A

Polyoma virus family

Neuropathy in transplant patients

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24
Q

What family does the merkel cell virus belong to? What does it cause?

A

Polyoma virus family

Merkel cell skin carcinoma (assoc with the majority of these)(

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25
Q

What are the structural characteristics of the papillomaviridae family?

A

Genome: small dsDNA (circular)

Non-enveloped

26
Q

What does papilloma viruses cause?

A

Wart-like lesions

While there are multiple types, the high-risk variation is assoc with genital cancer

27
Q

What are the structural components of the adenoviridae family?

A
  • med sized
  • linear dsDNA
  • fiber-spikes protruding from capsid to aid in attachment to cells
28
Q

Where are adenoviruses found to cause most infections? What diseases are associated with them?

A

Mucous membranes and lymphoid tissue

-acute resp distress, conjunctivitis, gastroenteritis

29
Q

What are the structural characteristics of the hepadnaviridae?

A
  • small enveloped viruses
  • circular, partially dsDNA
  • lipid and viral surface antigen on envelope
30
Q

What family is the hepatitis virus in? What does HepB cause?

A

Hepadnaviridae

Acute/chronic hepatitis and incr risk of liver cancer

31
Q

What are the structural characteristics of the herpesviridae?

A
  • Large, enveloped viruses
  • linear, dsDNA
  • latent infection capable
  • has its own DNA polymerase***
  • has glycoprotein spikes (peplomers)
32
Q

Where does herpes replicate?

A

DNA in the nucleus, proteins in the cytoplasm

33
Q

What is the result of the herpes virus infected cells?

A

Cytolytic (cells die after spread)

34
Q

What does EpiBarr virus cause?

A

Mono (most acute mono infections)

35
Q

What virus causes chickenpox and shingles? What family?

A

Varicella-zoster

-herpes family

36
Q

What virus causes oral and genital lesions (herpes)?

A

Herpes simplex 1 and 2

37
Q

What virus causes roseola? What family?

A

Human herpesvirus 6 and 7

38
Q

What virus causes kaposi sarcoma?

A

Human herpesvirus 8

39
Q

What are the structural characteristics of poxviridae?

A
  • Large, brick shaped
  • linear, covalently closed dsDNA
  • 100 proteins, large genome
  • encodes its own DNA/RNA polymerase
  • Replicates in the cytoplasm
40
Q

What diseases are associated with the pox virus?

A

Smallpox
Vaccinia
Molluscum contagiosum
Monkeypox

41
Q

What RNA forms can RNA viruses have?

A

Double or single strand RNA

Can have multiple segments

42
Q

How do RNA viruses get RNA polymerase? From host or endogenous?

A

They HAVE to produce their own (to transcribe mRNA from template and copy RNA genome into new genomes)

43
Q

Do RNA polymerases have proofreading? If yes or no, whats the impact on RNA viruses?

A

No; RNA error rates= a lot of mutations and changes in the genome (they mutate a lot and adapt quickly)

44
Q

What are some characteristics of picornaviruses?

A
  • RNA virus
  • Rhinovirus and enterovirus are the branches
  • naked
  • ssRNA genome
  • viral RNa genome undergoes translation upon infection
45
Q

What pH range does enteroviruses replicate at? Rhinoviruses?

A

Entero: -3-10 pH (WIDE range)

Rhino: 6-8pH (pretty much physiological pH)

46
Q

Where do picornaviruses replicate?

A

In the cytoplasm

47
Q

Where do enteroviruses primarily infect? Rhinoviruses? At what temps are they most optimized?

A

Entero: small intestine & 37*C

Rhino: Nasal mucosa & 33*C

48
Q

What unique translation feature does picornaviruses use?

A

They can shut off host-cell transcription to take over machinery of cytoplasm of the host cell

49
Q

What are some clinical syndromes of picornaviruses?

A
  • aseptic meningitis
  • encephalitis
  • common cold
  • Febrile rash illness
  • Conjunctivitis
  • Herpangina
  • Myositis and Myocarditis
  • Hepatitis
50
Q

What are some characteristics of paramyxoviruses?

A
  • negative ssRNA

- Enveloped

51
Q

What family of viruses does measles and mumps belong to?

A

Paramyxoviruses

52
Q

How are paramyxoviruses typically transmitted?

A

Respiratory route (they can cause respiratory tract infections)

53
Q

Where does the viral RNA enzymes come from in paramyxoviruses?

A

They bring them with them into the host cell

54
Q

What are the characteristics of orthomyxoviruses?

A
  • negative, segmented ssRNA
  • Enveloped (w/ surface glycoproteins)
    - HAS antigenic variation
55
Q

What are the two important glycoproteins in orthomyxoviruses? What do they do?

A

Hemagglutinin: attachment of virus to target cell

Neuraminidase: egress of virus from the infected cell

***change a lot in infections due to high variation

56
Q

What family does the influenza virus belong to?

A

Orthomyxoviruses

57
Q

Where do orthomyxoviruses enter the cell?

A

Endocytosis

58
Q

Where does the RNA of orthomyxoviruses travel first? Why?

A

To the nucleus (unlike most RNA); steals the cap structures of post-cell transcripts to transcribe viral mRNAs

1) mRNAs are more recognizable by host ribosomes
2) disengages host transcription due to lack of capping

*****this is target of many new antivirals

59
Q

What does antivirals target in orthomyxoviruses?

A

The RNA polymerase of the ortho

And maturation/release of the virus and genome

60
Q

What are the characteristics of the reoviruses?

A
  • dsRNA (8-11 segments)

- naked

61
Q

What are rotaviruses? What family is this in? How does it cause its symptoms?

A

Most common cause of infantile diarrhea worldwide

  • reovirus family
  • infects enterocytes and destroys absorptive enterocytes

Foundations- Block 1 (17 decks)

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