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Microbiology > module 6 viruses > Flashcards

module 6 viruses Flashcards

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1
Q

What are viruses

A

small non-cellular particles cannot replicate unless inside a living host
also called obligate intracellular parasite

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2
Q

What are the 2 components that make up a virus

A

its genome and capsid

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3
Q

What is specific about a virus genome

A

its either DNA or RNA
double or single stranded, circular, linear arrangement
size vary from few thousand to millions nucleotides

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4
Q

What are the 3 types of large viruses

A

pandoravirus: 2.5 million nucleotides
megavirus: 1.25 million nucleotides
mimivirus: 1.2 million

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5
Q

What is the structure of the capsid

A

membrane like protective structure- contains genetic material similar to nucleus of eukaryotic cells
either enveloped or non-enveloped

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6
Q

what makes up the envelope of the capsid

A

derived from host cell membrane and serves as additional barrier to external environment

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7
Q

What does it mean for a non-enveloped virus

A

virus surround by protein capsid: majority animal viruses are enveloped, plant viruses are not

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8
Q

What is required for a virus to replicate

A

host cell enzyme in order successfully replicate
outside viruses lie dormant- have no active metabolism
must have a way into and a way to exit the cell

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9
Q

What is the general life cycle of a virus

A
  1. virus attach to host cell and envelope fuses w/membrane and open- release capsid into cytoplasm
  2. once nucleotide enter cytoplasm, it uncoat( unravel) release viral genome into cell
  3. new viral protein produce using host cell protein/enzyme and build new particles
  4. newly released virus ext the cell, infect additional cell in same environment or new one
  5. once new host is found, process of attachment repeats along with entry and replication
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10
Q

What is a bacteriaphage( phage)

A

virus that infects a bacteria

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11
Q

What is the structure of a bacteriophage

A 
have icosahedral( 20 sided polygon) capsid head group and helical tail and fibers( legs aid in bind to host)
structure not seen to infect human/plants
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12
Q

How does bacteriophage get into a cell

A

Does not pass capsid into host cell
tail fibers mediate binding, helical tail penetrate host cell wall
viral genome injected into cytoplasm through helical tail

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13
Q

What are 2 forms of replication

A

lytic and lysogenic

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14
Q

Describe lytic bacteriophage

A

replicate in host bacteria until it lyses destroying host bacterial cell

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15
Q

Describe Lysogenic bacteriophage

A

Lysogenic bacteriophage can exist in non-replicative state so viral genome integrate in host genome
host cell replicates DNA as well as viral DNA
production of viral protein via transcription and translation is suppressed
stress can cause reactivation of replication of viral protein and re-enter lytic replication cycle

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16
Q

What is a prophage

A

lysogenic bacteriophage that has integrated into host genome

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17
Q

What is a viral titer and how is this important for research

A

amount of virus in culture
allow research to carefully and effectively plan infection experiments
too much virus: overwhelm and kill host
too little virus: take too long to grow new virus

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18
Q

What is Rubella

A

German Measles
virus is linear, single stranded, enveloped, RNA, 10-12,000 nucleotides
belong to Togaviridae family

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19
Q

How is Rubella transmitted

A

air borne particles: caught of infected patient
Pt is infectious 1 week before and after appearance of rash
eventually multiplies in upper respiratory and conjunctiva of the eye: travels from eye to GI, urinary tract, skin and CNS

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20
Q

What are Sx of Rubella

A

fever, flu like, conjunctivitis, red skin rash: trunk first then rest of the body
can be transmitted to fetus in pregnant women: cause damage to fetus eyes, ears, heart

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21
Q

Is Rubella preventable

A

yes: vaccine obtained about age 1

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22
Q

What is Mumps

A

Epidemic Parotitis
linear, single stranded, enveloped RNA 15,000 nucleotides
belong to Paramyxovirus family

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23
Q

How is Mumps transmitted

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A

transmit air borne droplets from infected individual

highly contagious- 7 days prior and 8 days after Sx show

24
Q

What are the Sx of Mumps

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A

cold: headache, fever, muscle ache, painful swelling of salivary parotid gland
swelling can occur in teste/ovaries and pancreas

25
Is Mumps preventable
yes with vaccine: MMR
26
What is chicken pox
Varicella Virus: Zoster Virus linear stranded- single, enveloped, DNA, 125,000 nucleotides long Herpesvirus family
27
How is chicken pox characterized
small itchy fluid filled blisters on any part of the body | highly contagious
28
How is chicken pox transmitted
contagious 1-2 days before rash appear and considered non-contagious when scabs form over blisters contact with blisters airborne droplets
29
Where does chicken pox virus remain
dormant in body | can reappear as shingles about age 60
30
What is shingles
Herpes Zoster: reactivate of VZV
31
How is shingles characterized
painful blisters as VZV lies inactive in nerves | blister localized and limited to small area
32
What are the Sx of shingles
first: severe pain, tingling, burins, where rash presents later once blisters form: possible to transmit virus to someone who has not had chicken pox or VZV vaccine
33
What is Tx for shingles
mild sx: over the counter pain meds | painful blisters: can get anti-viral drug acyclovir
34
What is small pox
vanilla virus has been eradicated linear, double stranded, enveloped DNA virus 186,000 nucleotides
35
What are the 2 variants of small pox
variola major: more severe and most common | variola minor:
36
How is small pox transmitted
transmits easily through air and direct contact
37
What are the Sx of small pox
high fever, rash in mouth/throat, rash appear externally face and then spread to arm/legs, hands and feet Rash: raised bumps filled with opaque fluid eventually form scabs: once fall off leave more resemble pitted scar
38
When was vaccine developed for small pox
1796 | is first infectious disease to be eradicated
39
What is Polio
Poliomyelitis single stranded, non-enveloped RNA 7700 nucleotides Picornaviridae family 30 nm in diameter: most significant small virus
40
How is polio characterized
when infected, enters CNS, replicate damage motor neurons | infected neurons are found in spinal cord, brain stem or motor cortex: causes temporary or permanent paraylsis
41
Is there a vaccine for polio
yes: developed in 1955- Johnas Stakle- 90% individual developed protective antibodies oral vaccine developed in 1961 both vaccines 95% effective in forming preventative antibodies
42
What is influenza
Orthomyxoviridae family single stranded, enveloped RNA 50-120 nm 3 subtypes: A, B, C
43
Which subtype of influenza is most pathogenic
A
44
What are the 2 glycoproteins in the viral envelope of influenza
HA: hemagglutinin: involved in entry of viral particle into host cell: 16 subtype N: neuraminidase: involved in budding and release of new viral particle from host cell: 9 subtype
45
What are the targets when building influenza vaccine
HA and N can appear in any combo and is not seen on every iron naming is based on which protein on envelope
46
How was the flu in 2009 and the Asian flu in 1957 named
H2N2: asian H1N1: 2009
47
What is HIV
Human Immunodeficiency Virus Retroviridae family linear, single-stranded enveloped 10,000 nucleotides
48
Describe structure of HIV
2 copies single stranded linear RNA enclosed by capsid surrounding 2 RNA strand is cone shape capsid with 2000 copies viral protein p24 viral envelope is derived from cell host membrane surrounds viral capsid
49
What is in the viral envelope of HIV
2 key glycoprotein: gp120 and gp41
50
How does HIV enter host cell
viral gp120 protein bind to host protein CD4, allows gp41 to bind to host chemokine receptor CXCR4 or CCR5
51
What happens after HIV has entered and finished uncoating
HIV protein reverse transcriptase acts on RNA= complementary DNA Now double DNA transport to nucleus and integrates into host genome
52
What happens after integration of HIV in host genome
virus rely primarily on host cell machine( envelope/ transcript) for replication once replicated: new virus assembled and released from ell to infect neighbor cells
53
What is the Tx for HIV
anti-retroviral meds: combat virus reproduction | if go untreated: turns to AIDS
54
What is AIDS
Acquired Immunodeficiency Syndrome
55
How is AIDS characterized
severe loss of body immunity: individual does not die from aids but other complications because of low immunity 35 million people have died and 37 million cases of HIV

Microbiology (7 decks)

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