Viruses Flashcards

Midterm 2

1
Q

Obligate Parasites

A

Viruses are NOT living creatures until they have attached to and invaded a living organism

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2
Q

DNA viruses

A

Hepatitis B
Herpes Simplex 1 (cold sores)
Herpes Simplex 2 (genital herpes)
Herpes Simplex 3 (Varicella Chicken Pox & Zoster Shingles)
Herpes Simplex 4 Infectious Mononucleosis (Epstein-Barr Virus)
HPV (genital warts)
Smallpox (Variola)

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3
Q

RNA Viruses

A

Influenza
Red Measles (Rubeola)
Pneuomonitis/Bronchiolitis (Respiratory Syncytial Virus RSV)
HIV and AIDS
Norovirus
Polio
German Measles (Rubella)
Hepatitis A and C
West Nile Virus
COVID19 (SARS)

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4
Q

Approximate size of viruses

A

Extremely tiny, within the realm of nanometers (bacteria are within the realm of micrometers)

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5
Q

How do viruses attach?

A

Viruses are host-specific and attach to receptor sites
1. Enveloped viruses take a bit of the host’s membrane system with them and are pleomorphic since the envelope is more supple than the capsid (glycoprotein spikes for attachment)
2. Non-enveloped viruses have only the capsid layer protecting the genetic material (capsid molecules for binding and attachment)

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6
Q

Types of Virus Morphology

A

-Helical
-Polyhedral
-Enveloped & Spherical
-Complex

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7
Q

Methods of Culturing Viruses

A

-Viral Plaque Method
-Animals and Transgenic animals
-Tissue Culture Method
-Cytopathic Effects
-Embryonated Eggs

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8
Q

Culturing

Viral Plaque Method

A

Growing a virus over a layer of bacteria on a plate (plaques are the holes in the bacterial layer which indicated areas of host cell death aka zone of lysis by virus)

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9
Q

Culturing

Tissue Culture Method

A

grow tissue cultures and put viral cells on them, watch them go

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10
Q

Culturing

Cytopathic Effects

A

unleash virus on host tissue and look for cytopathic effects (patterns) (can be used on chick and rat embryo cells)

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11
Q

Culturing

Embryonated Eggs

A

embryonated eggs have a variety of areas doe viruses to targets, eggs are innoculated with virus and are cultivated MOST COMMON METHOD USED TODAY since eggs are cheap and readily available

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12
Q

Methods of diagnosing virus

A

-Electron microscopy (to look at size, structure, and number & arrangement of capsomeres)
-CPEs, inclusion bodies in host tissue
-Serology
-Nucleic acid probes

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13
Q

T-Even Phages

A

-Important structures include the Polyhedral Capsid Head, DNA (genetic information), Helical Tail, Tail Sheath, Pin & Plate, and Tail Fibers
-Not enveloped and only attach to bacteria
-Best understood and most studied virus

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14
Q

T-4 Virus

A

Virus that typically parasitizes E. coli organisms

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15
Q

Life Cycle of Bacteriophage

A
  1. Attachment
  2. Penetration/Entry
  3. Biosynthesis
  4. Assembly/Maturation
  5. Release
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16
Q

Attachment

A

Tail fibers attach to host receptor proteins (very specific because of this) via random collision

17
Q

Penetration/Entry

A

Bacteriophage injects hydrolytic enzyme into host cell by contracting tail sheath and forcing the internal hollow tube within the tail through the host’s cell wall and membrane (like a hypodermic syringe)
*Bacteriophages for animal viruses enter via endocytosis, fusion, or direct penetration (non-enveloped bacteriophages)

18
Q

Biosynthesis

A

After entry, enzymes degrade the bacterial DNA and Bacterium stops synthesizing its own molecules and begins synthesizing new viruses under the direction of the viral genome

19
Q

Assembly/Maturation

A

Not entirely understood
Parts of the bacteriophage accumulate within the cell and spontaneously attach to each other to form new virions

20
Q

Transduction

A

Transfer of DNA from old host to new host when the viral capsid assembles around pieces of host DNA

21
Q

Release (bacteriophage life cycle)

A

Viruses are released from the host bacterial cell as the lysozome completes its degradation of the host’s wall and the bacterium lyses
-Non-enveloped: released from animal cells through exocytosis, which may cause lysis and death of the cell
-Enveloped: often released through budding or exocytosis. Virus exits cell with envelope derived from a plasma or organelle membrane. Host cells die eventually due to all the damage from the viral occupants

22
Q

Eclipse Period

A

the time period from attachment to pre-assembly where virions penetrate host’s cells. (time between successful cell infection and start of virus production)

23
Q

Burst Time

A

the time period from attachment to release (lysis). The number of virions released per infected bacterium

24
Q

Latency

A

when animal viruses remain dormant in host cells. In asymptomatic host, viruses are not usually released unless activated (Herpes Simplex, Chicken Pox/Shingles)

25
Q

Temperate Virus

A

viruses continuously released (Hepatitis B, HPV, HIV)

26
Q

Virus Prevention

A

Good hygiene, vaccines, anti-viral drugs (but not ABX)