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Virology > Nature of Human Viruses > Flashcards

Nature of Human Viruses Flashcards

1
Q

Why were viruses considered ‘filterable agents’?

A

Dmitri Ivanocski took the liquid that causes tobacco mosaic disease and filtered it to eliminate bacteria and spores. The resulting filtered liquid still caused disease, but the infection agent, viruses, could not be visualized.

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2
Q

Viruses are/are not alive

A

are NOT

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3
Q

Unlike bacteria, viruses cannot ______

A

replicate in broth

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4
Q

Viruses do not divide by binary fission. Instead, they….

A

infect a susceptible cell and take over the cellular machinery to make the cell into a virus-making factory

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5
Q

What do viruses require in order to replicate?

A

Living cells

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6
Q

What does NOT work on viruses?

A

antibiotics or antifungals

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7
Q

T/F: Some antiviral agents are available, but most viruses have no effective drugs

A

True

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8
Q

The virus ________ in the newly infected cell to initiate a new infection

A

disassembles

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9
Q

What do viruses use to complete their life cycle?

A

They use the host cell machinery to complete their life cycle. (Some people refer to them as obligate intracellular parasites)

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10
Q

What is the genetic material of viruses?

A

RNA or DNA

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11
Q

New virus particles are made from….

A

newly made viral proteins in the host cell

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12
Q

What happens to the newly made particles?

A

The newly made particles (virions) spread the new virus to new cells

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13
Q

A _______ is an infectious virus particle

A

Virion

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14
Q

Name the two types of viral capsids

A

Helical
Icosahedral

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15
Q

The _____ capsid can vary in length depending on the size of the viral RNA

A

helical

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16
Q

For human viruses, what type of viruses all contain helical capsid structures

A

All negative-sense RNA viruses

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17
Q

What do all helical capsids containing human viruses have?

A

A lipid envelope. They are all enveloped viruses!!

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18
Q

Most helical capsids do not have what?

A

do NOT have a rigid structure; think Ebola (spaghetti-like)

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19
Q

Viruses with ______ capsids can be enveloped or naked as opposed to _____ capsids that are all enveloped

A

icosahedral; helical

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20
Q

What are icosahedral capsids formed from?

A

From viral capsid proteins. Inside the capsid is the nucleic acid of the virus.

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21
Q

Why do the structure of icosahedral capsids need to be strong?

A

The structure needs to be strong enough to, in some cases, withstand stomach acid but still be able to open up once the virus has infected a new cell.

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22
Q

What is needed to from the icosahedron?

A

In many cases, only the viral capsid protein is needed to form the icosahedron. Once a sufficient amount of capsid protein is present, the icosahedron spontaneously forms. This property of capsid self-assembly is used to make the virus-like particles in the human papillomavirus vaccine.

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23
Q

T/F: Viruses are only ‘naked’ (containing no envelope lipid bilayer)

A

FALSE - Viruses can either be ‘naked’ containing no envelope lipid bilayer or evenloped.

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24
Q

What are viral envelopes derived from?

A

Infected cell membranes

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25
Q

The viral envelope glycoproteins are incorporated into the lipid bilayer. What are these proteins required for?

A

Entry into a cell. They disrupt the lipid bilayer, and the virus cannot enter cells.

26
Q

What prevents a virus from infecting a cell?

A

Neutralizing antibodies

27
Q

Neutralizing antibodies recognize ____________ on the virion

A

surface proteins

28
Q

Neutralizing antibodies for naked viruses bind….

A

the capsid proteins

29
Q

Neutralizing antibodies for enveloped viruses bind the…..

A

envelope glycoproteins embedded in the lipid bilayer

30
Q

++ssRNA

A

For single-stranded RNA viruses, their genome is the same sense as messenger RNA and is called positive-sense RNA viruses

31
Q

–ssRNA

A

Negative-sense RNA viruses, –ssRNA, are NOT like mRNA. They must use their genomic –ssRNA as a template to make mRNA

32
Q

Which viruses have a segmented genome?

A

BOAR viruses

Most viruses have one continuous segment of genetic material. However, the BOAR viruses have their genome contained in discrete pieces; they have a segmented genome.

33
Q

What are the BOAR viruses?

A

Bunyavirus
Orthomyxovirus
Arenavirus
Reovirus

34
Q

Linear single-stranded DNA (linear ssDNA) members:

A

Parvovirus

35
Q

Linear double-stranded DNA (linear dsDNA) members:

A

Adenovirus
Herpesvirus
Poxvirus

36
Q

Closed-circular double-stranded (circular dsDNA) members:

A

Papillomavirus
Polyomavirus

37
Q

Circular, most of the circle is double-stranded, but a small part is single-stranded (circular ds/ssDNA) member:

A

Hepadnavirus

38
Q

Single-stranded positive polarity (+ssRNA) members:

A

Hepevirus
Picornavirus
Calicivirus
Togavirus
Coronavirus
Flavivirus
Retrovirus (retroviruses have +ssRNA but incorporate two strands of the same RNA into the virion)

39
Q

Single-stranded negative polarity (-ssRNA) members:

A

Filovirus
Paramyxovirus
Rhabdovirus

40
Q

Segmented, single-stranded with negative polarity (segmented -ssRNA) members:

A

Arenavirus
Bunyavirus
Orthomyxovirus

41
Q

Segmented double-stranded (segmented dsRNA) member:

A

Reovirus

42
Q

Circular single-stranded negative polarity (circular -ssRNA) member:

A

Deltavirus (this is the Hepatitis D virus (HDV). It is not replication-competent and needs the help of the Hepatitis B Virus (HBV) to replicate).

43
Q

Describe Steady State virus-cell interactions

A

-In this infection, the virus does not kill the cell but does produce virus.
-This is productive. The virus is made and is non-cytocidal; the virus does not kill the cell.

44
Q

Describe Lytic/cytocidal

A

1) The virus kills the cell as part of its life cycle; cell death is needed to release the virus
2) This interaction is productive and cytocidal. The virus is produced, and it kills the cell

45
Q

Describe Cytopathic/cytocidal

A

1) The virus kills the cell but not as part of its normal replication. It just makes the cell so sick that it cannot live.
2) This infection is productive and cytocidal. It also produces virus and kills the cell.

46
Q

Describe Latent

A

1) Here, the virus infects cells and does not produce any virus but can reactivate.
2) This is non-productive (no virus made) and non-cytocidal (the cell is not killed).
3) The ability to become latent is an important feature of herpesviruses.

47
Q

The infected cell can fuse membranes of neighboring uninfected cells to form a large multinucleated cell

A

Syncytia Forming

48
Q

Cell-transforming

A

If a virus can transform a cell, it makes the virus more likely to cause cancer. Transforming a cell makes them immortal and able to grow on top of each other (no contact inhibition like most cells).

49
Q

List the viruses that cause cancer

A

EBV
HPV
Human Herpes Virus-8
HTLV
HBV
HCV

50
Q

EBV

A

(Epstein-Barr Virus)-Burkitt lymphoma, Nasopharyngeal carcinoma, oral hairy leukoplakia (in HIV infections)

51
Q

HPV

A

(Human Papilloma Virus) – Cervical, Anal, and Oropharynx

52
Q

Human Herpes Virus-8

A

Kaposi’s Sarcoma (in HIV infections, immunocompromised)

53
Q

HTLV

A

(Human T cell lymphotropic virus) Adult T-cell leukemia and lymphoma

54
Q

HBV

A

(Hepatitis B virus)-Hepatocellular carcinoma

55
Q

HCV

A

(Hepatitis C Virus)-Hepatocellular carcinoma

56
Q

***As far as the charts of different viruses, of the viruses discussed, you need to know the type of genetic material,
whether it is naked or enveloped, and capsid shape. You will also need to know the family of the viruses
discussed. For example, for HSV-1, know Herpesvirus, enveloped, icosahedral, and dsDNA. A trick to remember
icosahedral or helical is that all DNA viruses are icosahedral. In addition, of the RNA viruses, only the –ssRNA
viruses are helical, except for coronavirus.

A

See Study Guide #1!!

57
Q

Herpesvirus Family

A

“How Simple to Very Easily Catch 6, 7, or 8 Herpesviruses”
-Herpes Simplex 1 & 2
-Varicella Zoster
-EBV
-CMV
-Human Herpes viruses 6, 7, & 8

58
Q

List all of the DNA viruses

A

HHAPPPPy
-HBV
-Herpes
-Adeno
-Parvo
-Papilloma
-Polyoma
-Pox

59
Q

Picornavirus Family

A

PERCH (with 2 E’s)
-Polio
-Entero
-Echo
-Rhino
-Coxsackie
-HAV

60
Q

Flavivirus Family

A

“A WESTern Dentist Zombie YELLed Help”
-West Nile Virus
-Dengue
-Zika
-Yellow Fever Virus
-Hepatitis C Virus

61
Q

Paramyxovirus Family

A

PRM3-PaRaMyxo
-Parainfluenza
-RSV
-Metapneumo
-Measles
-Mumps

Virology (17 decks)

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