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III > WK 8- INFECTION AND IMMUNITY > Flashcards

WK 8- INFECTION AND IMMUNITY Flashcards

1
Q

What does virulence mean

A

degree of pathogenicity- highly virulent= more significant pathogen

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2
Q

What are opportunistic pathogens

A

Microorganisms that cause a disease in a compromised host rather than a healthy (non-compromised) host

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3
Q

How can flora and environmental bacteria be present but not create an infection

A

Infection will only occur if the bacteria breaches the surface/membrane and enters the body

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4
Q

What are the 3 factors that determine whether or not a pathogen can cause a disease

A
  1. route of entry
  2. number of infectious bacteria
  3. status of host defence (eg. if commensal flora or if immunocompromised)
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5
Q

What are the 4 species of pathogens and give a common example of each

A

Bacteria (neisseria meningitidis), Viruses (HIV), Protozoans (malaria), Metazoans (helminths)

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6
Q

Out of the 4 types of pathogens, which has the highest rate/ability of mutation

A

Viruses, follows by protozoans

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7
Q

What is a niche and how does it impact on immune response

A

Niche is the place in which a pathogen is most likely to survive and thrive-> the niche determines the bodys immune-> eg. if the organism’s niche is within the cell, the immune response cannot contain antibodies/complement as they cannot penetrate the cell

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8
Q

What is the adaptive immune response to extracellular bacteria

A

Primary response is humoral immunity-> antibodies

-Antibodies will eliminate bacteria & neutralise toxins

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9
Q

What is the innate immune response to extracellular bacteria

A

Primary response is complement activation->
- (LPS) activate the alternative pathway
–Phagocytosis
–Inflammatory response initiated by PAMPs (e.g. LPS, LTA, DNA, flagellin)

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10
Q

What is the adaptive immune response towards intracellular bacteria

A

Primary response is cell mediated immunity
-Th cell derived signals – CD40L & IFN- γ help macrophage to kill phagocytosed bacteria (vesicular microbe)
–CTLs (CD8) induce lysis of infected cells (cytoplasmic microbes)

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11
Q

What are the innate immune responses towards intracellular bacteria

A

Aim is to kill the infected cell

  • NK cells promote phagocytosis and killing
  • Direct stimulation by bacteria to produce IFN-γ-> macrophage activatin
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12
Q

What is the smallest type of infected particle

A

virus

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13
Q

True or false- viral genetic material can be RNA or DNA

A

true

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14
Q

What are the 5 types of viral infetions

A
  1. Acute
  2. Subclinical
  3. Latent
  4. Chronic
  5. Oncogenic
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15
Q

Describe acute viral infection

A

Release of virus causes lysis of host cells (lytic)

-Well defined recognisable symptoms→e.g. influenza, measles

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16
Q

Describe latent viral infection

A

Virus remains dormant in host cells, reactivated at later stage→ e.g. herpes viruses HSV 1&2, varicella zoster virus (chickenpox+shingles)

17
Q

Describe chronic viral infection

A

Virus remains in host > low level viral production and shedding
-No disease symptoms, unaware they are carriers→ e.g. Hep B, Hep C, HIV

18
Q

Describe oncogenic viral infection

A

Cause tumours→ e.g. HPV, Hep B, EBV

19
Q

Describe subclinical viral infection

A

No recognisable clinical signs, general malaise, slight fever, lymphadenopathy→ e.g. Rubella, EBV

20
Q

What are the 9 different ways in which a virus can be spread

A
  1. Saliva- EBV
  2. Mechanical trauma- Cowpox
  3. Bite-Rabies
  4. Injection- Hep B
  5. Generalized infection- Chickenpox
  6. Localised resp infection- Influenza
  7. Sexual intercourse- HIV
  8. Transplacental- Rubella
  9. Faecal-oral- Hep A
21
Q

What is a defensin and how does it work- what immune response does it belong to

A

Innate- they are small cysteine-rich cationic proteins released by neutrophils and macrophages-> increase membrane permeability of pathogens (aid in destruction)

22
Q

What innate immune responses are developed against viruses

A
  • Acts via Lysozyme, antiviral-cytokines (interferons) and NK cells-> these produce IFN-g, carry out ADCC, cause phagocytosis and cell death
  • also release defensins
  • activation of the complement pathways (alternative and classical)-> create MAC
23
Q

What adaptive immune responses are developed against viruses

A
  • Ag specific immunity, antibodies, cell mediated killing, memory cells
  • -> Antibodies act to neutralisation extracellular virus, aid in phagocytosis and opsonisation and promote cytotoxicity and complement activation
24
Q

What innate immune responses occur with extracellular protozoa

A

phagocytosis, complement activation

25
Q

What antibody responses occur with extracellular protozoa

A

opsonisation, complement activation, ADCC

26
Q

What antibody responses occur with intracellular protozoa

A

neutralisation to block entry to host cells

27
Q

What T cell responses occur with intracellular protozoa

A

Th1 cytokines to activate macrophages, Cytotoxic lymphocytes (CTL’s) kill infected cells

28
Q

What T cell responses occur with extracellular protozoa

A

Th2 cytokines for antibody response, ADCC

29
Q

What are examples of intracellular protazoa

A

malaria, leishmaniasis, toxoplasmosis

30
Q

What are examples of intracellular protazoa

A

amoebiasis, trypanosomiasis, giardiasis

31
Q

What are the 3 T cell receptors involved in HIV transmission

A

CD4 receptor, and 2 co-receptors (CCR5 or CXCR4)

32
Q

What is the major viral receptor involved in HIV transmission

A

Gp120

33
Q

How can meningococcal result in organ failure/death/disability

A

Infiltration of pathogen through mucosa causes cytokine activation→ raises TNF-α, IL-1, IL-6→ cause sepsis and can create endothelial damage and capillary leakage (causes the purpuric rash, shock, DIC, thrombolytic events)→ combination of poor tissue perfusion and coagulopathy leads to multiple organ failure and necrosis of extremities (dry necrosis)→ can lead to death or permanent disability

34
Q

What is the most important virulence factor in neisseria meningitides

A

Most important virulence factor is the presence of an outer polysaccharide capsule→ the capsule contributes to survival through inhibition of phagocytosis, but also in mitigating meningococcus’ susceptibility to drying

35
Q

What are the 3 cell types infected in HIV

A

CD4 T cells, macrophages and DCs

III (13 decks)

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