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Fungal/Virology > LEC 8 - Virus Structure + Function II > Flashcards

LEC 8 - Virus Structure + Function II Flashcards

1
Q

What are the two basic survival strategies for viruses?

A

Acute

– and –

Persistent infections

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2
Q

Describe: Acute viral survival

A

Lytic infections

Successive propagation in a series of hosts

Destroys host cells

Multiply rapidly until host immune system catches up

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3
Q

Describe: Persistant infections

A

Long term infection in single host

Transmission to new host occur but not as rapid

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4
Q

What is the fate of the host with non-lytic viruses?

A

Establigh a quiescent interaction with host cell

Host has an increase rate of survival since virus isn’t as damaging

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5
Q

What is the quiescent virus called?

A

Provirus

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6
Q

What can terminate the quiescent phase of a viral infection?

A

Environmental conditions

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7
Q

What are the three basic viral infection patterns?

A

Acute

Chronic

Latent

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8
Q

What are the three types of persistent infections?

A

Latent

Chronic

Transforming

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9
Q

Describe: Latent infections

A

Intermittent acute episodes

Between there is apparent absence of virus particles + very little synthesis

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10
Q

What are examples of latent infections?

A

Herpes

Feline viral rhinotracheitis

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11
Q

Describe: Chronic infections

A

Constant production of virus

Periods of time where symptoms are not present

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12
Q

What are examples of chronic infections?

A

Canine distemper virus

Old dog encephalitis

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13
Q

Describe: Transforming

A

Cells are immortalized

Properties are altered to those of cancer cells

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14
Q

What are five basic ways that persisting viruses are able to evade the host’s immune system?

A

Blockade APC mechanisms - change MHC expression

INterrupt cytokine synthesis or receptor function

Inhibit apoptosis induction

Evade antibody/complement killing

Avoidance

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15
Q

How are persistant viruses able to AVOID the immune system?

A

Infect non-permissive/quiescent cells

Store genome with no lysis

OR

Invade immunological priviledged sites = lack MHC markers

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16
Q

What are the three methods viruses can move throughout the body?

A

Blood

Lymphatics

Neurons

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17
Q

What occurs with viremia in regards to replication?

A

Virus enters blood = Viremia

Another round of replication

Amplifies infection

Secondary viremia

= MORE DISSEMINATION

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18
Q

Describe: Iceberg concept

A

Infection does not always mean disease

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19
Q

What are the three things a virus must do?

A

Infect host

Persist + Spread to damage tissues

Be transmitted

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20
Q

What are the three parts to clinical disease?

A

Death

Severe disease

Mild illness

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21
Q

What is sub clinical disease?

A

Infection without clinical illness

22
Q

What are the six susceptibility factors?

A

Age

Nutritional status

Immune function

Pregnancy

Stress

Presence of receptors

23
Q

Why are embryos susceptible to viral infection?

A

Rapidly dividing

24
Q

What is a virion? What must happen with a virion?

A

They are inert

Must be implanted on suitable part of host body

Enter the body

25
Q

What types of tropism are there?

A

Cellular

Tissue

Host

26
Q

How does tropism occur?

A

Virus is highly selective for certain kinds of receptors

27
Q

What symptoms generally occur with non-specific host responses?

A

Vague clinical symptoms

Fever + Malaise

Due to production of cytokines

28
Q

What can cause hemorrhage due to a virus?

A

Vascular bed damage

29
Q

What disease process can occur when a virus causes endothelial damage?

A

DIC

30
Q

What are examples of CPE (visable cytipathic effects)?

A

Inclusion body formation

Syncytia formation

Nuclear/morphological modifications

31
Q

Describe: Syncytia formation

A

Multinucleated giant cells

32
Q

What viruses cause multinucleated giant cell formation?

A

Herpes

Paramyxo

33
Q

What causes inclusion body formation?

A

Site of viral replication

Or

Product accumulation

34
Q

What special inclusion body goes with the rabies virus?

A

Negri bodies

35
Q

How can a diagnosis be made with direct examination of clinical samples?

A

Electron microscopy

Viral cytopathic effects

Antigen detection with fluorescent antibody

Hemabsorption

Hemaggultination

36
Q

Describe: Hemadsorption

A

RBC’s adhere to surface of infected cells expressing viral hemagglutinin

37
Q

Describe: Hemagglutination

A

RBCs are cross-linked by viron hemagglutinin protein and form a network

38
Q

How can you detect viral genetic material?

A

PCR

(Polymerase chain reaction)

39
Q

What is the down side to using PCR as a diagnosis?

A

Will reveal latent infections + specimens harboring inactivated virus

So dont know if thats whats causing the problem or not

40
Q

What kind of virus can be detected with PCR?

A

DNA
RNA

41
Q

What type of PCR is used for RNA virus?

A

rt-PCR

42
Q

How are cultures used to make a diagnosis?

A

CPE

Plaque formation (cell killing) to assay virus

Pock formation

Death or pathology in whole animal assay

43
Q

What titer are you looking for in serology?

A

Greater than 4x’s

44
Q

Describe: ELISA

A

Immobilized viral antigens or antibodies capture specific reactive antibodies to host

45
Q

What are three major ways viruses are controled?

A

Quarantine

Vaccination

Antiviral agents

46
Q

What is the problem with anti-viral agents?

A

Halt viral replication

Toxic to host because viruses are so intermigled with our cells

47
Q

What is another name for vaccination (process by which it works)?

A

Artifical acquired active immunity

48
Q

What can be given to induce passive immunization?

A

Immunoprophylaxis by provision of immune serum globulin

49
Q

What is the goal of biosecurity?

A

Prevent disease

– and–

Prevent outbreaks

50
Q

What is involved in biosecruity?

A

Controlling the pathogen transmission by understanding the relationships between host + disease + environment

Fungal/Virology (26 decks)

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