Lecture 5: Antiviral immunity and Prophylaxis

Question 1

What are the parts of the innate immune system? Adaptive immune system?

Answer 1

• Innate immunity: Natural barriers, IFN, NK, Macrophages.
• Adaptive immunity: Cytotoxic T cells, antiviral antibodies, helper T cells

Question 2

Where are B cells made in the bird?

Answer 2

Bursa of fabricius

Question 3

What antibody is present mainly in the mucus membranes? What about near the alveoli?

Answer 3

MM: IGA is present here mostly.
IgG is alveoli areas

Question 4

What size of foreign antibodies can pass through the nose, bronchi, bronchioles, alveoli?

Answer 4

• Foreign antigen through nose 15 mcL
• Bronchi : 10 mcL
• Bronchioles: 5 mcL
• Alveoli: 1 mcL

Question 5

What are the stages of phagocytosis?

Answer 5

• Stages of phagocytosis
• CAID -> Chemotaxis -> adherence -> Ingestion -> Destruction

Question 6

What is the purpose of IFN’s? Are IFN’s specific to viruses? What about cell specific? Species specidic?

Answer 6

• IFN -> Chemical produced by viral infected cells to alert for response to viral infections.
• IFNs not virus specific but cell specific in production and effects and is Species specific.

Question 7

What are IFN’s? What can inactivate them?

Answer 7

• Glycoprotein’s, stable at ph2 and resistant at 56 degrees c for 1 hour
• Can be inactivated by treatment with proteolytic enzymes.

Question 8

What is the purpose of developing a fever when sick? What does the fever mean?

Answer 8

• Fever helps induce immune response.
• Fever is important. It is synthesizing the immune response. The more fever the larger the immune response. The fever will trigger IFN when it gets above 40 degrees c

Question 9

Which IFN has the most genes that encode it?

Answer 9

• IFN-a : 20 genes incode this
• 1 gene encodes Beta and gamma

Question 10

What is the definition of an IFN?

Answer 10

IFNs: sets of proteins released by the virus infected cells which react with the surrounding non infected cells rendering them resistant to this type of viral infection

Question 11

What are type 1 IFNs?

Answer 11

IFN alpha (leukocyte IFN (monocytes) B lymphocytes)

IFN beta (fibroblast IFN, Epithelial cells)

Question 12

What are type 2 IFNs?

Answer 12

IFN gamma

(Immune IFN ( some activated t cells, NK cells)

Question 13

What are IFN inducers?

Answer 13

• Infectious or inactivated virus induce the production of IFNs for 20-50 hrs after exposure
• Viruses that might multiply slowly and not damage the cell or the synthesis of protein early are good IFN inducers
• Cells of bone marrow, spleen, and macrophages are highly IFN producers
• Polynucleotides (Poly-IC) are good IFN inducers

Question 14

What is the antiviral mechanisms induced by IFNs?

Answer 14

• 1.Block viral mRNA synthesis
• 2.Block the translation of viral mRNA

Question 15

How does antigen processing/ display occur with MHC - I Molecules?

Answer 15

Viral peptides are produced from proteins in the cytosol and transported to the ER to bind to Class I MHC complex

The peptide/Class I MHC complex transported to the cell surface and displayed for recognition by the CD8+

Question 16

How does antigen processing/ display occur with MHC - II Molecules?

Answer 16

Viral proteins are ingested into vesicles and degraded into peptides -\> 
They bind to the class II-MHC that transported to the same vesicles -\>
The class II-peptide complex are expressed on the cell surface and recognized by CD4 T cells

Question 17

What immune cells are important for stimulating NK cells?

Answer 17

decrease in MHC I, increase in stimulatory ligand, IFN alpha and Beta , and IL- 12, IL 18

Question 18

How do B lymphocytes react to a virus?

Answer 18

B lymphocytes trigger plasma cells and antibody secretion.

Question 19

How do monoclonal cells prevent virus infectiow

Answer 19

They act as a barrier, so it competes for the receptors on the cell and the virus cant transmit active infection.

Question 20

How do CD4+ T lymphocytes and macrophages prevent virus infection?

Answer 20

• releases cytokines which:
• activates macrophages
• Inflammation
• Stimulates B lymphocytes

Question 21

How do CD8+ T lymphocytes and macrophages prevent virus infection?

Answer 21

This cell is a cytotoxic t cell. It will kill the infected cell and cut its losses.

Question 22

What cells are involved in the immune response to viral infection? When does each cell peak? How long does the innate immune system last? When does the adaptive immune system kick in?

Answer 22

1. ) Type - 1 IFN’s ( peak about day 2 and then declines)
2. ) NK cells ( peaks about day 3 and then declines)
3. ) CTL (Starts around day 2 but plateus around day 7 then declines around day 10)
4. ) Antibodies (Starts around day 5 sometimes, but mostly at day 7)

Innate immunity begins at day 1-5, at day 5 adaptive immune system takes over.

Question 23

What does CD4+ T cells do when they recognize a virus? CD8+

Answer 23

CD 4+: Attract other immune cells and stimulate B- cells to produce

CD8+ : -Slow down the viral infection

-Kill the virus infected cells

Cytotoxic-T cells: Kills the virus-infected cells through
the release of some toxic chemical mediators

Question 24

What are TCRs?

Answer 24

T cell receptors (TCRs): specifically recognize and bind to some antigenic peptide bound to MHC molecules

Question 25

What is the mechanism of the NK cell destruction of a virus?

Answer 25

* Virus infected cells express multiple stress indicators and virus infection inhibits expression of cell proteins * NK cell’s multiple activating and inhibiting receptors are bound * When activation stimuli overcome inhibition, cell death is initiated * Cytotoxic granules orient to the cell junction and are released * Perforin creates access to the target cytosol delivering Granzymes (serine proteases that mediates cell death)

Question 26

What happens when activation stimul overcome inhibition? What are perforins?

Answer 26

- Cell death is initiated. Perforins: allows access to target cytosol to send in granzymes

Question 27

What is the mechanism of cytotoxic t cell killing virus infected cells?

Answer 27

Viral proteins degraded into peptides and subsequently bound by recently synthesised class I MHC proteins which transported to cell surface CTL with the T cell receptors specific for that peptide/MHC complex determine or see the cell infected by this binding interaction Once multiple receptors including CD8 also bind and tight cellular junction established . Cytotoxic granules directed into cell junction NK cells and perforins (serine like proteases) get access to the cytosol of the target cells Cell death

Question 28

What are the antiviral effects of antibodies?

Answer 28

- agglutination of viral particles by antibodies. - Antibody mediated triggering of phagocytosis.

Question 29

How does complement try to prevent virus infection of cells?

Answer 29

Complement competes for receptors to block entry. Multiple things are occuring at once and working synergistically to protect the host.

Question 30

In what kind of placenta is their 100% transfer of blood between mother and offspring? How can this affect vaccines?

Answer 30

Hemochoral placentas have 100% placental transfer. Must be careful with vaccines because maternal antibodies can neutralize vaccines.

Question 31

How does colostrum protect young animals? When should they receive it? What happens after 2 days? Where does the immunity go after that?

Answer 31

Colostrum intake is required to protect young animals against septicemic disease Needs to be given in first few hours before the intestinal pore closes and the newborn cannot benefit the same way. After a few hours the pores of the intestines become to narrow to accept the immunoglobulins from the colostrum.

Question 32

What is some of the disadvantages of immune response? What is one clinical example?

Answer 32

Immune response to viruses could be on some occasions, a disadvantage * Animals infected or vaccinated with the ICHV-1 live vaccine * Dogs develop anterior uveitis leading to corneal edema and opacity * The cornea is infiltrated by neutrophils, attracted by virus antibody complexes deposited in tissue • Accumulation of neutrophils which release enzymes damage corneal epithelial cells resulting in inflammation and edema, then corneal opacity in dogs • Blue-eye develops about 1 to 3 weeks after the onset of infection and usually resolves spontaneously once the virus is eliminated. Example: BLUE EYE DISEASE

Question 33

What is aleution disease? What animals is it affect in? What can you see with their kidneys? What is seen in the serum of infected animals ?

Answer 33

* Aleutian disease: persistent Parvovirus infection first recognized in Aleutian coat color * Animals develop complex immune lesions including glomerulonephritis and arteritis * Serum protein electrophoretic patterns • The serum of infected animals shows a polyclonal gammopathy: the gamma globulin accounts for 62.4% of serum proteins • The normal level is 14.3% You will see enlarged kidneys with edema in the kidneys. They also will have increased kidney values that indicate renal failure.

Question 34

What are some strategies of viral evasion to host immune destruction?

Answer 34

1. ) inhibition of antigen presentation 2. ) Modulation of MHC class I expression 3. ) Antigenic variation 4. ) Prevention of apoptosis 5. ) cytokine targeting 6. ) latency 7. ) destruction of immune cells

Question 35

How does amantidine kill influenza?

Answer 35

penetration and uncoating

Question 36

How does acyclovir affect herpes conjunctivitis?

Answer 36

Attacks DNA replication.