Viruses And Virology

Front 1

Virus

Back 1

• An infectious agent that typically consists of a nucleic acid molecule in a protein coat
• Too small to be seen by a light microscope
• Only able to multiply within living cells of its host
• Referred to as being acellular or subcellular

Front 2

Virus Nucleic Acid made up of?

Back 2

Either DNA or RNA, never both

Front 3

Prion

Back 3

• Is a misfolded protein
• Not a virus
  
• No nucleic acid
• When it comes into contact with normal proteins, causes them to misfold
• Infection usually happens in the brain of the infected individual

Front 4

Which organisms suffer attack from viruses?

Back 4

All organisms

Front 5

A virus is said to be_____when outside of host cells

Back 5

Inert

Front 6

Species Specific

Back 6

Refers to the fact that most viruses can only infect one species of organisms

Front 7

Most viruses nucleic acid is made up of?

Back 7

Most are RNA, some are DNA

Front 8

Viruses range in size from?

Back 8

20nm-1,000nm

Front 9

Viral Genome

Back 9

• Is very small group of genes that encode for protein capsids and enzymes the virus cannot obtain from its host

Front 10

Classification of Viruses is Based upon?

Back 10

1. Morphology
2. Nucleic Acid Type (RNA or DNA or D.S.)
3. Host organism
4. Mode of Replication
5. Presence or absence of an Envelope

Front 11

Virion

Back 11

A complete, infective form of a virus when it is outside of the host cell

Front 12

Viroid

Back 12

Infectious agent of plants consisting of nucleic acid without a capsid

Front 13

Lysogeny

Back 13

Viruses that incorporate their nucleic acid into that of their host. The lytic cycle is suppressed.

Front 14

Lytic Cycle

Back 14

Results in the destruction of the infected cell and its membrane

Front 15

Prophage

Back 15

The state of the cell when the viral nucleic DNA has been incorporated into that of the host cell

Front 16

Lysogenic Cells

Back 16

Name for an infected host cell being immune to reinfection by the same type of virus but not to infection by other viruses.

Front 17

Lysogenic Conversion

Back 17

• Refers to the exhibition of new properties by the host cell after viral infection.
  
• Ex: Corynebacterium diptheriae only produces the toxin responsible for diptheria when phage infected
  

Front 18

Induction

Back 18

• Caused by a spontaneous event, such as exposure to UV light or to a chemical
• Causes the virus to convert from lysogenic stage to a lytic cycle

Front 19

Four Morphologies of Viruses?

Back 19

1. Naked Virus
2. Enveloped Virus
3. Complex Virus
4. Helical Virus

Front 20

Naked Virus

Back 20

A virus composed of a nucleic acid core which is surrounded by a protein capsid. The capsid is made of small units called capsomers.

Front 21

Enveloped Virus

Back 21

A virus with an envelope that is typically derived from portions of the host cell membranes, but include some viral glycoproteins.

Front 22

Complex Virus

Back 22

• Consist of a capsid then sheath bellow followed by a base plate with tail fibers branching off, and pins bellow
  
• Ex: Bacteriophages

Front 23

Helical Virus

Back 23

• Consist of spiral nucleic acid, surrounded by a spiral capsid made up of capsomers
• Ex: Ebola virus

Front 24

Three categories of Viral Infections?

Back 24

1. Acute Viral Infections
2. Latent Viral Infections
3. Slow (Virus) Infections

Front 25

Acute Viral Infections

Back 25

• Characterized by a rapid onset of disease, relatively brief period of symptoms, and resolution within days

Front 26

Process of Acute Viral Infections

Back 26

• Patient is infected
• They go through an incubation period
• Then an expression of symptoms
• Recovery (Hopefully)
• The infected individual is completely free of the virus
• Ex: Common cold, caused by rhino viruses

Front 27

Latent Viral Infections

Back 27

A type of persistent viral infection in which the viral production ceases after the initial infection and the viral genome is not eradicated but lies dormant in the host cells, and may be reactivated under certain conditions

Front 28

Process of Latent Viral Infections

Back 28

• Patient is infected
• Then goes through the incubation period
• Expression of symptoms
• Recovery
• Virus remains dormant in patient cells, may or may not become active
• Ex: all herpes viruses, and HIV

Front 29

Slow (Virus) Infections

Back 29

• Caused by viruses or virus like entities (prions)
• a.k.a. persistent infections
• usually see asymptomatic primary infection
• very long incubation periods followed by slow, yet relentless progression until patient's death
• Patient's tend to have genetic predisposition
• Disease will progress more quickly if patient becomes severely immunocompromised

Front 30

Kuru

Back 30

• Is a Slow Infection/persistent infection
• also known as Laughing/shaking Disease
• associated with canibalism
• Was found in a tribe in New Guinea called the Fore, who ate their dead tribal members during funeral ceremonies
• Prion of Kuru is concentrated in the nervous system, so the tribe became infected
• Long incubation period of 5-20 years
• Clinical stage lasts about 12 months, then death

Front 31

Progression of Kuru

Back 31

• Ambulent Stage: Stage in which the patient is shaky on his or her feet/staggering and speech begins to slur
• Sedentary Stage: Patient can no longer walk, and will experience tremors
• Terminal Stage: Patient cannot sit up unassisted, has trouble swallowing, and experiences outbursts of uncontrollable laughter

Front 32

Extra credit: What 2 dogs does professor Shimeld own?

Back 32

Anatolian Shepard, and Sheltie