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Microbiology > Basic virology > Flashcards

Basic virology Flashcards

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Biology 101 flashcards
1
Q

What is a virus?

A

obligate intracellular parasite that replicate by self-assembly of individual components rather than binary fission

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2
Q

Virus genomes can be:

A

RNA: ss circular or linear ; ds linear
DNA: ss linear, ds circular or linear

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3
Q

3 forms of capsids

A

helical, icosahedral, complex

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4
Q

virion for naked virus=

A

genome+ capsid

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5
Q

Some nucleocapsids are surrounded by a lipid envelope that is derived from ____.

A

cellular membrane

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6
Q

Which is more stable; naked or enveloped?

A

naked

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7
Q

How do enveloped viruses spread?

A

large droplets, secretions, organ transplant, blood transfusions

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8
Q

Major steps in viral replication

A

attachment–> penetration–> uncoating–> early transcription–> genome replication–> late transcription–> assembly–> release

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9
Q

What happens in early transcription?

A

synthesis of nonstructural proteins. DNA viruses use host RNA pol, RNA virus use virally encoded RNA dependent RNA pol

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10
Q

What happens in late transcription?

A

synthesis of structural proteins

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11
Q

Where are RNA viruses assembled?

A

cytoplasm

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12
Q

Where are DNA viruses assembled?

A

nucleus

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13
Q

+RNA virus genome replication

A

translated as polyprotein–> cleaved–> RNA dep polymerase transcribes -RNA as template

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14
Q

-RNA genome replication

A

-RNA virus carries a RNA dependent RNA polymerase–>+RNA

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15
Q

The biological assay for infection

A

plaque assay

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16
Q

What is MOI?

A

ratio of the number of infectious particles to number of target cells. 1 would be 60% of cells, 5-10 ensures all cells are infected

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17
Q

Eclipse period

A

post-penetration phase until virus can be detected intracellularly, ends at virus assembly

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18
Q

Latent period

A

post penetration till cells can be detected extracellularly

19
Q

Complementation

A

exchange of proteins

20
Q

With complementation, would a mutant be able to replicate in a 2nd cell?

A

No

21
Q

Recombination

A

an exchange of genetic material on the same segment of genome

22
Q

Will a mutant virus be able to replicate in a 2nd cell after recombination?

A

yes

23
Q

Recombination occurs frequently with what type of viruses?

A

DNA

24
Q

Ressortment

A

an exchange of genetic material on different segments of genome

25
Q

____ is probably the most common route of infection.

A

inhalation

26
Q

2 ways of localized spread of viruses

A

release of virus to surrounded cells, syncytia formation

27
Q

How might a virus spread from the original site of infection?

A

gain access to lymphatics or blood

28
Q

Incubation period

A

period postinfection prior to the onset of symptoms

29
Q

Acute phase

A

symptomatic pase

30
Q

3 forms of persistent infection

A

chronic, latent, transforming

31
Q

What is a transforming persistent infection?

A

integrates into cellular DNA or is otherwise maintained in the cell and immortalizes the cell, alters its growth properties

32
Q

What is the first defense against viruses?

A

IFN and NK cells

33
Q

IFN induced pathways to prevent viral infection

A
  1. PKR ptwy inactivates translation initiation factor eIF-2–> inhibits viral protein translation
  2. 2-5A activates RNas L which cleaves RNA
  3. Mx ptwy are GTPases that inhibit RNA polymerase activity
34
Q

Role of Ab in viral infection

A

can neutralize virus binding or facilitate lysis of enveloped viruses with complement

35
Q

Flu like symptoms are caused by ____

A

IFN and lymphokines

36
Q

Inflammation is caused by ____.

A

t cells, macrophages, PMNs

37
Q

Hemorrhagic disease is caused by____.

A

T cells, Ab, complement

38
Q

3 types of antivirals

A

vaccine, Ig, drugs

39
Q

Which type of viral vaccine gives a strong IgG, IgA, and T cell response that is long lasting?

A

attenuated

40
Q

Which viral vaccine gives short term immunity that is mostly IgG

A

killed virus

41
Q

How is immune globulin used for viral vaccination?

A

pre- and post- exposure prophylaxis

42
Q

What determines the shape of virus capsids?

A

The shape of capsids is determined by the shape and interaction of capsomeres, which self-assemble.

43
Q

Which type of capsid morphology is best suited for concerted packaging

A

Helical morphology is best suited for concerted packaging as the self-assembling capsomeres can spiral along with the replicating nucleic acid.

44
Q

Which type of capsid morphology is best suited for sequential?

A

Icosahedral capsids are best suited for sequential packaging as, typically, a procapsid of partially assembled capsomeres forms and then fully assembles once a unit genome has been inserted into the procapsid.

Microbiology (2 decks)

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