Idit Exam 3 - Saviola - Viral Structure And Replication Ii And Virological Methods

Front 1

What are the two patterns of viral infections?

Back 1

1. Localized
2. Disseminated

Front 2

What is a localized infection?

Back 2

Viral multiplication and cell damage is localized near the site of entry

Front 3

What are the steps of a disseminated infection?

Back 3

1. Local multiplication at the site of entry.
2. Spread through the lymphatics to the blood stream and circulation in the blood. (primary viremia).
3. Multiplication at secondary sites.
4. Secondary viremia.
5. Infection of the target organ.

Front 4

What is the incubation period of a virus? Is the patient symptomatic or asymptomatic during this time?

Back 4

Steps 1-4 of a disseminated infection - before infection of the target organ?

Asymptomatic

Front 5

What are some sites of virus entry into the host?

Back 5

1. Respiratory Tract
2. GI tract
3. GU tract
5. Skin
6. Conjunctiva
7. Oral Mucosa

Front 6

What is the sequence of events that occurs during an infection of Varicella-Zoster Virus (VZV)?

Back 6

1. Infection via conjuctivis and upper respiratory tract
2. Replicates in primary lymph nodes
3. Primary viremia
4. Secondary viremia
5. Infects neurons/CNS

Front 7

What occurs during primary viremia of VZV infection?

Back 7

Replication of virus in liver, spleen, etc.

Front 8

What occurs during secondary viremia of VZV

Back 8

Infection of skin and rash

Front 9

What is an inapparent infection? (she skipped this topic in lecture...)

Back 9

Asymptomatic viral infections

Front 10

What are two ways an inapparent infection can occur?

Back 10

1. Infection by attenuated virus

2. Effective host defense mechanisms

Front 11

What is an advantage of getting an inapparent infection?

Back 11

It may confer immunity in the host

Front 12

What is an acute infection?

Back 12

Disease begins shortly after virus infects the host.

Front 13

What are three outcomes of an acute infection?

Back 13

1. Virus is eliminated from the body

Persistent infection:
2. Latent infection
3. Chronic infection

Front 14

Does the host take a short or long time to recuperate from an acute infection?

Back 14

SHORT

Front 15

What is a latent infection?

Back 15

Viral particles are not demonstrable but viral nucleic acid is.

Front 16

What is a chronic infection?

Back 16

Virus particles are released from infected cells --> viral particles is demonstrable

Front 17

What are four ways your immune system responses to viral infections?

Back 17

1. Virus neutralization by antibodies
2. Cell-mediated immunity
3. Interferons
4. NK cells

Front 18

How do interferons battle viral infections? What are the INF that battle viruses?

Back 18

They inhibit viral multiplication and may provide temporary and localized protection for nearby cells

Alpha and Beta. NOT Gamma

Front 19

How do antibodies battle viruses?

Back 19

They prevent entry and uncoating

Promote phagocytosis and destruction, antibody-complement mediated cytolysis of infected cells, or antibody dependent cell mediated cytotoxicity

Front 20

How do antibodies prevent viral entry and uncoating?

Back 20

1. Steric hindrance
2. Capsid stabilization and structural changes so that it cannot uncoat

Front 21

Which virus can work as a teratogen? How does it spread to the fetus?

Back 21

Rubella

It can cross the placenta

Front 22

How does your immune system block Rubella from crossing the placenta?

Back 22

Antibodies can block it

Front 23

How do cytotoxic T cells help battle virus infection?

Back 23

Important for recovery from primary infection and preventing reinfection

Detects viral peptides presented on MHC class I --> destroys that cell

Front 24

What are the most important cytokines in antiviral immune responses?

Back 24

Type 1 INF alpha and beta. NOT gamma

Front 25

How does a virus infected cell get activated to produce INF alpha/beta?

Back 25

Induced by:
1. Active or Inactivated viruses
2. dsRNA

Front 26

Are interferons host species specific, virus species specific, or both?

Back 26

Only host species specific

NOT virus specific

Front 27

How does INF alpha/beta work against viruses?

Back 27

INF is released from the infected cell --> binds to receptor on nearby non-infected cells --> activates txn factor --> products can:
1. Degrade viral mRNA
2. Inhibit viral protein synthesis
3. Promote apoptosis of viral infected cells

Front 28

What is a negative effect of INFs?

Back 28

Causes flu-like symptoms

There are side effects of INF therapy

Front 29

What is one example of a treatment using INFalpha?

Back 29

To treat chronic type C Hep

Front 30

Which response to viral infection is quicker? NK cells or T cell response?

Back 30

NK cells - part of innate immunity

Front 31

What are 6 ways viral diseases can be controlled?

Back 31

1. Prevention of transmission
2. Public health surveillance
3. Education
4. Isolation of cases of diseases
5. Passive immunization
Active immunization- either live attenuated, inactivated, or subunit vaccines are used.

Front 32

How does a viral DNA vaccine work?

Back 32

DNA is engulfed by dentritic cells and presented to T cells --> elicits CMI

Front 33

Does attenuated or inactivated vaccines have longer immunity?

Back 33

Attenuated

Front 34

What antibodies do attenuated and inactivated antibodies produce?

Back 34

Attenuated: IgG and IgA

Inactivated: IgG

Front 35

Which mounts a better cell mediated response - attenuated or inactivated?

Back 35

Attenuated

Front 36

Which has reversion to virulence - attenuated or inactivated?

Back 36

Attenuated - rarely

Inactivated - NO

Front 37

What are 4 things required to eliminate a virus from a population?

Back 37

1. No animal reservoir
2. Good vaccine
3. Few or no subclinical cases (including latent infections)
4. One or only a few antigenic type with no antigenic switching

Front 38

How do new viral diseases in humans typically emerge?

Back 38

Existing viruses that are transmitted from other species as zoonoses

Front 39

What are the three contributing factors to new viral diseases? What are some examples?

Back 39

1. Political/social/environmental changes that increase human contact with an infected carrier or vector (HIV)
2. Genetic changes like point mutations (influenza, HIV) and intramolecular recombination
3. Genetic reassortment (Influenza)

Front 40

How does viruses act like parasites?

Back 40

1. Needs to be transmissible. If mobility of host is required for transmission, virus may not be as virulent
2. If disease is vector or water borne, don't need direct contact for transmission
3. Virus in a new host species may be more virulent than in a long term host species

Front 41

How do you treat virus diseases?

Back 41

1. Treat the symptoms
2. Immune serum - best if early - before exposure or during incubation period
3. Drugs - but limited

Front 42

What are 5 lab methods to diagnose viral infections?

Back 42

1. Isolation and growth of virus
2. Cytopathic effects in cells
3. Electron microscopy to detect viral particles
4. Detection of viral components (proteins, enzymes, nucleic acids)
5. Evaluation of the patient’s immune response (serology)

Front 43

How do you cultivate viruses in the lab?

Back 43

1. Tissue culture with host cells
2. Embryonated egg
3. Intact animal

Front 44

How do you use an embryonated egg/intact animal to study viruses?

Back 44

Infect egg/animal and then see if there is pathology

Front 45

What are two consequences of a viral infection?

Back 45

1. Proliferation of host cell (transformation) --> can become cancerous

2. Cytopathic effect

Front 46

What are the three cytopathic effects viruses have on our cells?

Back 46

1. Cell death and lysis
2. Formation of syncytia
3. Formation of inclusion bodies

Front 47

What do you see in the microscope when cell death/lysis is occuring as a result of viral infection?

Back 47

Rounding of cells --> they loose contact with supporting surface --> lysis

Front 48

From what kind of viruses do you see syncytia formation?

Back 48

Viruses with F protein

Front 49

What are inclusion bodies?

Back 49

Viral protein product aggregates in an infected cell

Front 50

What kind of inclusion bodies does HSV produce?

Back 50

Cowdry type A

Front 51

What kind of inclusion bodies does Rabies produce?

Back 51

Negri bodies

Front 52

How do you determine the number of infectious units of a virus?

Back 52

Serial dilution

Front 53

What do you look fore in a viral cultivation?

(she skipped this slide -__-)

Back 53

1. Plaque formation (viral lysis of cells in tissue culture)
2. Focal cytopathic changes in tissue culture
3. Focal proliferation of cells in tissue culture
4. Pock formation in membranes of chicken embryonated egg
5. Infection in experimental animals