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Microbiology > Lecture 15: Polio sIgA, Sec immune system & Virus neutralization > Flashcards

Lecture 15: Polio sIgA, Sec immune system & Virus neutralization Flashcards

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Biology 101 flashcards
0
Q

Explain how Ag at one mucosal site results in Ab protection at all mucosal sites?

A
  • Specialized Ag- presenting cells (APC) (M-cells) within sites, present these antigens and unique T and B cells specific for this Ag then react and clone. This results in IgA producing B cell clones specific to that antigen.
  • These multiplying daughter B cells migrate to other mucosal sites and start secreting the IgA dimers.
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1
Q

What is the role of IgA?

A
  • Involved in surface immunity

- Major Ab at mucosal surfaces and secretion within and outside the body.

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2
Q

Following release of these “emigrant” B cells the dimeric Ig-A molecules are picked up by what?

A

Poly-Ig Fc receptors that are on the tissue-side surface (inside-or baslolateral-surface) of submucosal epithelium

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3
Q

The Ig A is bound by the ____________, then taken up by the epithelial cells and extruded through the other side of the cell onto the mucosal surface ( other, or lumen surface).

A

Fc receptor

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4
Q

While in the cell the Fc receptor is cleaved by a _____________ but a portion is left clinging to the Ig A, and is still there after the IgA is released in to the lumen.

A

protease

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5
Q

What is the clinging part of the Fc receptor called?

A

The secretory component

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6
Q

What does the secretory component help do?

A

Helps protect secretory IgA (sIgA) dimers from proteases at the mucosal surfaces.

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7
Q

How does IgA pass to neonates in milk?

A

Through passive immunity from mom at the GI lumen.

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8
Q

Does the sIgA pass through the lumen into the baby’s vasculature or tissues?

A

No; IgA passive immunity protects the oral and gut mucosa of babies.

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9
Q

What offers protection for the tissues/blood for babies?

A

Ig G passive immunity from placental transfer

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10
Q

Where is the one surface site where IgA is not the major antibody involved in protection?

A

The cervical space between teeth and gingiva

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11
Q

What are some functions of SIgA?

A

Dimeric sIgA functions to

1) neutralize toxins and viruses at mucosal surfaces and block colonization of bad organisms.
2) Decreases unwanted immune rxn to FOOD.

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12
Q

sIgA is sticky and binds to what? And what does this prevent?

A

Binds to mucous preventing its rapid loss by the flushing action of saliva.

***It is also insensitive to acids and proteolytic enzymes!

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13
Q

True or False SIgA is a poor activator of complement and an inconsistent opsonizer?

A

True

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14
Q

True or False. Some medically important bacteria (N. gonorrhoeae, N. meningitides, S. pneumonieae, and H. influenzae have a virulence factor that produces proteases that degrade SIgA?

A

True

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15
Q

What system is partially Invovled in preventing any destructive immune reactions to our food?

A

IgA system mechanisms (Oral tolerance) are and they also serve to protect us from GI pathogens.

16
Q

What is anergy?

A

immune unresponsiveness

17
Q

What does high dose Ag feeding result in?

A

the induction of anergy (immune unresponsiveness)

18
Q

What does feeding of multiple low doses of Ag induce?

A

Induces regulatory T cells that secrete the inhibitory cytokine TGF-Beta.

Note: ***Lack of Inflammation to food may also play a role.
(Inflammation may be required for initial Th cell responses)

19
Q

What are the secondary lymphoid tissues?

A

Peyer’s patches, MALT ( mammary associated lymphoid tissues), BALT (bronchial associated lymphoid tissues), GALT (gut associated lymphoid tissues)
* More than all other immune tissues combined

20
Q

What are M- cells?

A

M-cells process and present external Ags on class II HLA molecules. Specialized Th cells respond to the Ags and help local Ag specific B cells respond and clone.

21
Q

What sticks to mucins and is resistant to proteases?

A

sIgA

22
Q

Poliovirus is a member of what virus family?

A

Picornavirus that is (+) ssRNA enterovirus.

  • Small
  • Non-envelope (naked virus)
23
Q

Where does the Poliovirus specifically bind and replicate ?

A

in the oropharynx and the GI mucosa

24
Q

How is the Poliovirus (Picornavirus) spread?

A

Mainly spread by fecal contamination of food and water.

***Virus is extremely stable due to lack of envelope.

25
Q

What are the signs/symptoms of the Poliovirus?

A
  • It actually is usually asymptomatic (BIG ICEBERG EFFECT)

- However, since it is neurotropic it can cause CNS infection and paralysis if “viremia” occurs and it becomes systemic.

26
Q

What antibody can prevent the initial establishment of infection?
What antibody prevents viremia spread to the target tissue (CNS), and therefore disease ?

A

SIgA and IgG respectively.

27
Q

What is the Salk vaccine?

A

-Non infectious and inactivated
-Injected
-induces great “IgG” protection, which neutralizes systemic viruses.
(good systemic bc of IgG and poor surface Ab response bc of little IgA)

28
Q

What is the Sabin vaccine?

A
  • infectious, & live (attenuated vaccine)
  • induces great “SIgA” protection, which neutralizes the virus before it even can start an infection at the primary mucosal infection sites.
  • Ingested orally
  • Good surface response (sIgA ) and good IgG response since it infects gut epithelial cells.
29
Q

Which vaccine is considered a “bystander” immunization of family?

A

Sabin (Attenuated)

30
Q

Which vaccine does a good job at protecting us from getting polio in blood stream?

A

Salk and Sabin because both have good IgG reponse (blood and tissues)

31
Q

Which vaccine induces a very good mucosal sIgA response?

A

Sabin (Attenuated)

Note: India uses this vaccine provides whole immune response.
Benefit: This will neutralize any polivirus ingested, thus stopping an infection from ever getting started.

32
Q

What is poliomyelitis?

A

A viral disease that can affect nerves and can lead to partial or full paralysis.

  • Entry into mouth
  • Replication in pharynx, GI tract, local lymphatics
  • Blood viremia- spread to lymphatics and CNS
  • Viral spread along nerve fibers
  • Destruction of motor neurons in spinal cord
  • First described by Michael Underwood in 1789
  • 21,000 cases in the US in 1952
33
Q

What are some characteristics of Poliovirus?

A
  • Enterovirus- Picornaviridae +ssRNA
  • Non- Enveloped
  • Three serotypes: 1,2,3
  • Spread by fecal-oral route
  • Rapidly inactivated by heat, formaldehyde, chloride, UV light
34
Q

What are outcomes of poliovirus infection:

A

Asymptomatic: 95%
Minor non-CNS illness: 4%
Non paralytic aspectic meningitis: 1%
Paralytic: 0.5%

35
Q

What is the reservoir for poliovirus?

A

Only infects humans

36
Q

Transmission of Poliovirus?

A

Fecal-oral and oral-oral possible

Microbiology (10 decks)

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