Podcast
Questions and Answers
What is the significance of tolerance in the immune system?
Which factor is associated with variable vaccine effectiveness?
Which diseases currently have no vaccines available?
What approach is being researched for vaccines targeting oral diseases?
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Which of the following is a challenge faced by vaccines against certain protozoan diseases?
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What is the main reason vaccination is preferred over natural disease for immunity?
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What is herd immunity primarily aimed at protecting?
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What effect does vaccination have on the incidence of diseases?
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Which of the following diseases has been almost eradicated due to vaccination efforts?
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What is a major claimed cause that has been misattributed to vaccines, despite lacking scientific support?
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What is one primary mode of transmission for poliomyelitis?
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What aspect of vaccines has raised concerns about scientific misconduct?
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Which method is NOT commonly used for virus detection in research?
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What is the relationship between vaccination and the immune response?
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What role do regulatory T cells (Tregs) play in immunological tolerance?
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What is the main concern related to the MMR vaccine?
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What factor can significantly influence the effectiveness of immunological tolerance?
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What impact do high vaccination rates have on public health?
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In terms of vaccine studies, what is a consequence of scientific misconduct?
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What distinguishes active immunity from passive immunity?
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Which method is commonly used for virus detection in research?
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Study Notes
Vaccination and Tolerance
- Vaccination is a key method for disease prevention in a population.
- Tolerance is a mechanism that regulates the immune system's response to antigens to prevent it responding to harmful substances like food, commensal bacteria, and self-antigens.
- Learning outcomes include contemplating the role of tolerance in immune response, understanding the rationale for vaccination, describing various vaccine types, explaining vaccine functions in stimulating immune responses, and exploring emerging vaccine issues.
- Acquired immunity is either active or passive, based on natural infection or vaccination.
- Active immunity can develop from catching an infection or from vaccination.
- Passive Immunity occurs when an uninfected individual receives antibodies from another (e.g. from mother to infant).
Immunity
- Immunity is inherited, acquired, or induced resistance to infection by a specific pathogen.
- Tolerance helps maintain a stable immune response that does not react to self-antigens and harmless substances in the body.
- Tolerance encompasses multiple mechanisms like central and peripheral tolerance involving T and B cells, nonreaction to potential antigens, and suboptimal response due to repeated exposure (immunological tolerance).
T & B Cell Tolerance
- B cells mature in the bone marrow; T cells mature in the thymus.
- Selection of T and B cells continues in other lymphatic tissues (e.g. lymph nodes, spleen).
- Central tolerance happens in the thymus (T cells) and bone marrow (B cells).
- Peripheral tolerance occurs in lymph glands, lymph tissue, and circulation
- Mechanisms in central tolerance include receptor editing, anergy, and apoptosis (clonal deletion).
None Reaction to Foreign Antigen
- The homeostatic system is maintained by regulatory T cells.
- Regulatory T (Tregs) cells produce immunosuppressive cytokines, such as IL-10, TGF-β, and others.
Immunological Tolerance
- Immunological tolerance is a preventative mechanism to limit tissue damage from unresolved infections or prolonged inflammation.
- Repetitive antigen exposure reduces inflammatory responses (e.g. TNF).
- Tolerance isn't a complete down-regulation; some functions aren't impacted (e.g. IL-8).
How to Acquire Immunity
- Natural immunity involves catching an infection naturally.
- Acquired immunity is either active or passive.
- Active immunity involves catching an infection or vaccination leading to natural production of antibodies/immunity.
- Passive immunity involves antibodies produced elsewhere being given to an uninfected individual.
Acquired Immunity: Passive Immunity
- Protection is transferred from an immune individual (e.g., mother to child).
Acquired Immunity: Active Immunity
- Protection is acquired by exposure to microbial antigen (either infection or vaccination).
- Active immunity results in a (long-term) memory response, and an ability to recognise the antigen.
Active Immunity: Details
- Protective immune response develops after the second or third vaccine dose (Boosters)
- Antibody titers for inactivated antigens diminish over time. Vaccine boosters can be used at periodic intervals to increase antibody levels and immunity.
Live Attenuated Vaccines
- Live attenuated vaccines are weakened versions of pathogens.
- They have reduced virulence to not cause harm.
- They mimic natural infection to mount a robust immune response.
Problems with Live Vaccines
- Viruses can revert to wild-type strains causing disease.
- Cannot be given to people with weakened immune systems.
- Need for refrigeration can cause problems with storage and transit, limiting accessibility.
Pfizer and Moderna: mRNA
- mRNA vaccines contain a segment of the virus genetic material to code for a protein.
- Cells use this material to create the protein.
- This unique protein is recognised by the immune system.
- This response creates immune memory, so bodies can fight the virus in future.
Oxford/AstraZeneca: Viral Vector
- Viral vector vaccines use a different virus type to deliver a part of the pathogenic virus' genetic material.
- This triggers an immune response.
Dangers Associated With Vaccines
- Attenuated vaccines risks include reversion to wild-type forms and severe disease in immunodeficient patients.
- Killed vaccines may pose risks of vaccine not being killed, or contaminants with animal viruses or from endotoxins.
Vaccines for Oral Diseases
- Caries (Streptococcus mutans): Cross reactivity with endocardium possible, antibodies target enzymes, glucans, adhesins. Antibodies.
- Periodontal disease: Bacterial cause, host response problems.
- HPV: Infections affects respiratory and anogenital tracts.
HPV and Cervical Cancer
- HPV prevalence is extremely low at young age.
- Risk of high-risk HPV (16, 18) infection increases.
- Viral proteins inactivate tumor suppressors (p53 and Rb).
HPV and Oropharyngeal Cancer
- HPV16 is a primary cause of Oropharyngeal cancer.
- Affects the base of the tongue, back of the throat, and tonsils.
HPV Vaccine: Gardasil® (UK)
- Four strains of HPV targeted.
- Highly effective in preventing infections, precancerous lesions, and genital warts.
Update - Gardasil 9® (UK)
- Nine strains of HPV targeted.
- Effective in preventing additional types of HPV-related cancers.
Issues Surrounding HPV Vaccine
- JCVI recommends HPV vaccination to boys in the UK later.
- Reports of serious side effects in adolescent girls who received the HPV vaccine.
Scientific Responsibility
- Measles cases in England and Wales (1996 - 2018) show fluctuation.
Vaccine Controversy
- Vaccine controversy is not a new phenomenon (e.g. historical depictions).
Major Diseases for Which There Are No Vaccines
- Summary of many diseases and issues.
Summary of Tolerance and Vaccination Notes
- Tolerance and vaccination are crucial in controlling how our immune systems react. Vaccination remains a key way to protect against most diseases.
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Description
Explore the vital concepts of vaccination and immunity through this quiz. Understand the mechanisms of acquired immunity, the role of tolerance in the immune system, and the various types of vaccines. This quiz will test your knowledge on how these elements contribute to disease prevention and health.
