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Microbiology II > Lecture 1 -2 viruses > Flashcards

Lecture 1 -2 viruses Flashcards

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Biology 101 flashcards
1
Q

What is required for a virus to stick to and enter a cell?

A

Spike

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2
Q

what is the protein bottle that contains viral genome called?

A

capsid

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3
Q

what makes up the envelope of some virus

A

parts of the host cell membrane that buds off with viral pieces inside.

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4
Q

What type of immune cells kill virus?

A

Natural killer - because they don’t have MHC

CD* killer T - because they present virus on MCH I

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5
Q

What is a B cells function in viral immunity?

A

makes antibodies that block the spikes on virus making it impossible for them to bind and infect cells

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6
Q

What is a virus?

A

Renegade genes packed in a protein coat

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7
Q

What is the viral genome made of?

A

RNA - single or double

DNA - single or double

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8
Q

what are the two protein coat, “capsid” shapes?

A

Icosahedral - soccer ball

helical - pipe shaped

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9
Q

what is the viral budding process?

A

virus leaves in membrane bubble provided by host cell

envelope has spikes embedded in it.

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10
Q

Where do virus have spikes?

A

Capsid - if they don’t have envelope

Envelope - only if they have one.

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11
Q

Which virus type, enveloped or not is more hardy?

A

The non enveloped virus is more hardy. The capsid with the spikes is not sensitive to drying like the enveloped one.

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12
Q

What are the 4 medically relevant responses of host cells to viruses?

A

1- Lytic
2-non lytic
3- latent
4-transformation

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13
Q

What type of virus causes lytic response mostly?

A

Non enveloped virus, capsid only

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14
Q

What type of virus causes non lytic response mostly?

A

enveloped viruses mostly

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15
Q

What is an example of a latent virus?

A

Herpes

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16
Q

What is meant b a latent response to virus?

A

The virus quits replication for quite a while but it can reactivate years later

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17
Q

Describe the transformation response to viral infection?

A

uncontrolled replication of host cell

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18
Q

Example virus that causes transformation?

A

HPV - causes warts and sometimes cancer

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19
Q

Are the double stranded RNA viruses enveloped?

A

Double stranded RNA viruses are NON-ENVELOPED - hardier

20
Q

Are they single stranded RNA viruses Enveloped?

A

Single stranded RNA viruses can be either ENVELOPED OR NON-ENVELOPED

21
Q

Are single stranded DNA viruses enveloped?

A

Single stranded DNA viruses are NOT ENVELOPED - hardier

22
Q

Are double stranded DNA viruses enveloped?

A

Double stranded DNA viruses can be either ENVELOPED OR NON ENVELOPED

23
Q

what determines what cells a virus can infect?

A

Spike proteins that are either on the envelope or the capsid if their is no envelope.

24
Q

What are the two key steps for viral replication?

A

1 - virus cause replication of their genome

2- virus must produce (+) positive strand mRNA to replicate their proteins

25
Q

What are the 6 general steps of viral replication?

A 
1 - viral ATTACHMENT via spike
2 -  viral PENETRATION
3 - UNCOATING capsid when inside cell
4 - REPLICAITON of viral genome
5- ASSEMBLE new viral particles
6 - virus RELEASED from host cell
26
Q

What are the targets for anti virals?

A

each of the 6 steps of viral replication

27
Q

How does the replication of DNA and RNA viruses differ?

A

DNA viruses use the host cells DNA dependent DNA Polymerase and DNA dependent RNA ply to replicate. It doesn’t need to have code to make the polymerase

28
Q

What type of virus needs to have a gene for polymerase enzymes?

A

RNA viruses need to have a gene for RNA dependent RNA poly and RNA dep DNA poly because humans in general never go from RNA to RNA or RNA to DNA, we don’t have the enxymes

29
Q

If a DNA virus is replicating what happens?

A

1 - transctiption via host enzymes to mRNA
2 - translation to viral proteins
3 - translated viral proteins take DNA and replicate it into more DNA
4 - the more DNA is transcribed and translated to more viral proteins
5- nucleocapsids are formed

30
Q

What is essential for viral RNA to be replicated? what type must it be?

A

Viral RNA must be in the positive sence because only then will it be recognized as mRNA by host cell enzymes

31
Q

How does a (+) ssRNA virus replicate?

A

1 - translation via host enzyme
2- viral proteins that make RNA dep RNA poly
3 - Viral enzyme turn + RNA to (-) RNA.
4- (-) RNA is replicated lots into (+) RNA by the same viral enzyme
5 - replicated (+) RNA is used to make proteins to make virus

32
Q

How does (-) ss RNA replicate?

A

1 - virus must have brought its on RNA dependent RNA polymerase that creates (+)ssRNA from the (-)ssRNA
2- the (+) ss RNA makes mRNA to make proteins
3 - (+)ssRNA is copied into lots of (-)ssRNA to be put in viral capsid.

33
Q

How does double strand + RNA replicate?

A

Just like the (-)RNA

b\

34
Q

What are the two ways that (-) ssRNA replicates?

A

1 - Via complementary (+) ssRNA intermediate

2 - Via a DNA intermediate - brings enzyme with it. -

35
Q

What enzyme is required to go from RNA to DNA?

A

reverse transcriptase - HIV

36
Q

What do all viruses need to carry out replication?

A

they need to be able to synthesize (+) strand mRNA

37
Q

What is a viroid?

A

infectious nucleic acid polymers that lack capsids;

38
Q

what is viral agent in blood?

A

viremia

39
Q

what is an infectious agent that is only protein?

A

prions - so far it is known that they infect only animals and humans.

40
Q

Which direction can viral infections spread? 2

A

1 - vertically - mom to neonate
2 - horizontally - person to person
3 - both

41
Q

How are horizontal infections spread?

A 
air
water
food
contact
insects
trauma to barrier
normal flora in immunosuppressed
42
Q

what is the iceburg effect?

A

many infections occur with little to no obvious symptoms and are followed by immune memory.

43
Q

What must happen for patient to get a clinical disease with infection?

A

the number of microorganisms must exceed a certain threshold, below this threshold there will be no signs or symptoms

44
Q

How does infection progress if immune system works?

A

enough microorganism to cross threshold, overtime show overt symptoms, immune system kick in and eventually not symptions, then but is gone

45
Q

What is the common path for polio?

A

asymptomatic infection for most people, they spread it for a while but 99% of people don’t get sick

46
Q

what is an example of a recurrent illness?

A

herpes with intermitant relapses

Microbiology II (8 decks)

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