Defence and vaccination against infection Flashcards

1
Q

What is active immunisation?

A

Achieved via vaccination which induces host immune response of B and T cells

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2
Q

What is passive immunisation?

A

Injection of pre-formed immunological mediators such as the gamma-globulin antibodies. These are IgA, IgM and IgG.

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3
Q

What is passive immunisation a treatment for?

A

Hypogammaglobuniemia: low levels of antibodies
Maternal antibodies
Tetanus, gangrene, snake bite, HepB

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4
Q

What is an essential feature of the adaptive immune response?

A

Clonal expansion of T lymphocytes

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5
Q

What are effector mechanisms of natural protection?

A

Lysis of infected target cell by T cells with antigen
Release of lymhpokines which mediate macrophages and other WBC
Antibody synthesis

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6
Q

What are the types of vaccines?

A

Live vaccines and non-living vaccines

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7
Q

What are the live vaccines?

A

Weakened form of pathogen by reducing its virulence. This can be natural or artificial.

There is a risk it may revert to the form capable of causing disease via mutation. Can be ingested and single dose.

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8
Q

What are the benefits of live vaccines?

A

Live attenuated vaccines can replicate and generate an identical response to natural infection and the natural immunity acquired.

However, the protection reduces over time so re-immunisation is important.

Cheaper than inactivated vaccines.

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9
Q

What is the immune response for live vaccine?

A

IgA, igG and IgM antibodies.

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10
Q

What are the artificial vaccines?

A

Adminstered via injection and requires adjuvant to stimulate the immune system, mediated by IgG only. It has a high cost

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11
Q

What are examples of viral infections treated by artificial vaccines?

A

Measles, mumps, rubella, rabies, Hep A, polio and yellow fever

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12
Q

What are examples of bacterial infections treated by artificial vaccines?

A

Salmonella, vibrio cholerae, bordatella pertussi and e.coli

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13
Q

What is the treatment for smallpox vaccine?

A

Live vaccine which uses cowpox, a weaker strain similar enough to grant immunisation without causing severe disease.

Artificial vaccine.

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14
Q

What are non-living vaccines formed of?

A

This is achieved by growing pathogen in a culture and using heat or chemicals to inactive it. Includes:
Antigenic parts of a pathogen
Killed whole pathogen
DNA/RNA from pathogen

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15
Q

What is a subunit vaccine?

A

Non-living vaccine which contains a portion of the pathogen to trigger immunogenicity.

Typically, it is most effective when used with an adjuvant, a substance that can be pathogenic or non-pathogenic like aluminium to cause a heightened immune response.

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16
Q

What is an example of a subunit vaccine?

A

DTP: diptheria, tetanus and pertussis. Contains tetanus toxin and bordatella that acts as adjuvant for toxins.

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17
Q

What is diptheria?

A

Severe bacterial infection which targets the upper airways and causes sore throat, difficulty breathing and death.

Caused by corynebacterium diphtheria, a gram positive bacilli.

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18
Q

What is tetanus?

A

Bacterial infection by clostridium tetani produce tetanus toxin which binds to post synaptic receptor and inhibits neurotransmitter signals from renshaw cells for inhibition of movement. Causes stiffness and leads to difficulty breathing. Toxin is used as a carrier in the subunit vaccine DTP for immunogenicity.

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19
Q

What type of bacteria is clostridium tetanus?

A

Gram positive bacilli which is anaerobic.

20
Q

What is pertussis?

A

Bacterial infection caused by gram negative bacilli bordatella pertussis.

This leads to violent coughing spells and swollen airways, causing difficulty breathing

21
Q

What is an adjuvant vaccine?

A

Additives to vaccines especially subunit in order to stimulate immunogenicity. It enhances inflammation and provides microbial signals to increase immune response.

They can be cell material like DNA particles, or synthetic like aluminium.

22
Q

What are examples of adjuvants?

A

Used in the COVID-19 vaccine as lipid nanoparticles
Aluminium in HepB and HPV vaccine
Squalene in flu vaccine and H1N1

23
Q

What is the routine for vaccinations in 2-6 months?

A

2-6 months: DTP vaccine, polio, meningitis, Hib

24
Q

What is the routine for vaccinations in 18 months?

A

18 months: MMR vaccine

25
Q

What is the routine for vaccinations in 10-16 years?

A

DTP, BCG vaccine for tuberculosis

26
Q

What is smallpox?

A

Double stranded DNA virus which is airborne and replicates in the lymphoid organs such as bone and liver via bloodstream travel in viraemia. It causes osteomyelitis (bone inflammation) meningitis and pneumonia.

27
Q

What is subclinical infection?

A

Infection by pathogen that causes little/no symptoms and below the threshold for clinical detection.

28
Q

What is poliovirus?

A

Single stranded positive sense RNA virus with naked icosahedral shape that leads to neurological symptoms such as severe paralysis. There are 3 serotypes, PV-1, PV-2 and PV-3 so there is no cross immunity.

29
Q

How does polio virus replication occur?

A

Enters via faeco-oral route through contaminated water. Acts as mRNA and immediately undergoes translation by host cell ribosome and cleaved as a polyprotein to form proteins such as polymerase template for new RNA strands.

30
Q

What is poliomyelitis?

A

Polio virus binds to motor neurons and cause degradation of the anterior horn of motor neurons, leading to paraesthesia, meningitis of the brain and spinal cord and in severe cases, paralysis of the respiratory muscles.

31
Q

What is the vaccination for polio virus?

A

Live vaccines and attenuated vaccines.

32
Q

How does the live polio vaccine act?

A

Orally administered and Grown in cell culture and induces lifelong immunity without requiring booster vaccines. Indirect community immunisation through spread of attenuated virus.

33
Q

What are the issues with the live polio vaccine?

A

It may replicate and lead to poliomyelitis. Because it is live, may spread to other people without consent, especially harmful.
May not be safe for immunocompromised people.

34
Q

How does the inactivated polio vaccine act?

A

Injection- Polio virus is treated with formaldehyde to inactivate it and induces immunity in nerve cells.

There is no protection in the gut, however it is beneficial for reducing risk for poliomyelitis and safe for immunocompromised.

35
Q

What are the issues with the inactivated polio vaccine act?

A

Does not produce gut immunity, requires booster vaccine. The community requires higher vaccination rates for herd immunity.

36
Q

What are the live vaccines?

A

MMR vaccine
BCG vaccine
M.Bovis vaccine

37
Q

What is the MMR vaccine?

A

Combination LIVE vaccine to treat measles, mumps and rubella that is routinely prescribed to infants. Combination vaccine ensures that only 2 injection courses are required.

38
Q

What is the BCG vaccine?

A

Vaccine for prevention of tuberculosis, only given to those deemed at risk like travellers abroad. This is only required once.

It is no longer part of routine vaccination as rates had fallen enough to not justify use.

39
Q

What is the M bovis vaccine?

A

Live attenuated vaccine to prevent tuberculosis induced meningitis, given at birth. There are many strains with variable efficacy.

40
Q

What is mycobacterium bovis?

A

Disease in cattle that spreads to humans and causes tuberculosis.

41
Q

What is HPV?

A

Double stranded DNA virus with many strains, of which strain 16 and 18 cause cancer. HPV vaccine is scheduled for 12 and 13 year olds

42
Q

What is SARS-COV2?

A

It has a positive sense single strand RNA virus Binds to ACE2 protein receptor present on most cells in the body via glycoprotein spike. Caused immunothrombosis, especially in infected people.

43
Q

How do COVID-19 vaccines work?

A

mRNA vaccine and viral vector vaccines.

44
Q

How does the mRNA vaccine work?

A

Generates synthetic mRNA corresponding to spike and insertion of genetic material of the spike protein into the patient. Results in generation of antigen proteins to induce immune response

45
Q

How does the viral vector vaccine work?

A

Isolates genetic material corresponding to spike and inserts this into patient to induce B and T cell immunity. Virulence gene is removed but capacity to enter cells remains to be transcribed by the patient’s ribosomes and synthesis antigen proteins to induce immunogenicity.