BIOL122 WK2 Immunity
Immunity|
Factors Affecting Immunity:
Age:
- Neonates and elderly are at increased risk of infections
- Neonates susceptible to pathogens like E. coli
- Elderly more prone to lower respiratory tract infections
Genetics:
- Genetic predisposition to susceptibility or lower immune response
Underlying Diseases:
- Acute infections can increase risk of subsequent infections
- Chronic conditions like cardiovascular disease, obesity, diabetes can impair immunity
- Immunocompromised states (e.g., HIV, cancer) lower immunity
Nutrition:
- Balanced diet provides nutrients for effective immune function
Medications:
- Immunosuppressants and corticosteroids can depress the immune system
Stress:
- Chronic stress leads to glucocorticoid secretion and reduced immune cell activity
- Occupational exposure (e.g., healthcare workers, childcare workers) increases risk
Vaccinations:
- Provide artificial exposure and prepare the body to fight pathogens
- Herd immunity protects vulnerable populations when vaccination rates are high (>85%)
Antibodies
Vaccines and Immunity|
Principles of Immunization:
- Utilizes the body's specific (third-line) immune defense
- Artificial exposure: Exposes the body to a version of the pathogen to build immune memory
- Allows for a quicker and more robust response upon subsequent exposure
Immunisations: process by a person made immune or resistant to infections disease
Body makes antibodies against antigens
Memory cells remain
Destroys antigen if re exposed
Antibodies for destruction
Mechanisms of Antibody-Mediated Pathogen Elimination:
- Labeling pathogens as foreign, activating complement system
- Attracting phagocytes to ingest and break down pathogens
- Stimulating inflammation - second line defences
- Preventing viral and bacterial adhesion to host cells
- Precipitation and agglutination of pathogens
- Neutralization, preventing pathogens from binding to host cells
- Opsonization, facilitating phagocytosis of pathogens
Primary Antibody Response:
- First exposure to an antigen
- Initial production of IgM, followed by slower IgG response
- Leads to formation of memory B cells
Secondary Antibody Response:
- Upon subsequent exposure to the same antigen
- Rapid and robust production of IgG antibodies
- IgG is more effective at destroying the antigen and associated pathogen
- Provides enhanced protection compared to the primary response
Criteria for Effective Vaccines:
- Protect against the relevant disease
- Induce specific immune memory
- Safe, with benefits outweighing risks
- Provide sustained, long-term protection
- Generate memory B cells and IgG antibodies
Vaccine Hazards:
- Adverse reactions (e.g., anaphylaxis, allergic responses) - redness swelling
- Weighing risks vs. benefits of the vaccine:
Prevalence of disease
Severity of disease
Morbidity and morality
Types of Vaccines:
1. Whole Virus/Bacterium Vaccines:
a. Live Attenuated:
- Whole pathogen in a weakened state ( measles, rubella ( MMR combined vacine) varicella ( chicken pox) and yellow fever.
Advantages: Strong, long-lasting immunity, easy to create
Disadvantages: Potential to revert to virulent state, storage/dilution challenges - not safe for all people, administration errors.
b. Inactivated (Killed):
- Whole pathogen, but dead ( polio, hep A and flu)
Advantages: Cannot revert to virulent state, excellent stability
Disadvantages: Longer production time, less potent immune response
2. Subunit Vaccines: just the parts of the pathogen that trigger an immune response. Antigens
Use only the antigenic parts of the pathogen ( whooping cough, meningococcal, human papillomavirus ( HPV)
Advantages: Strong immune response, safe for most patients
Disadvantages: May require multiple doses
3. Toxoid Vaccines: vaccine against toxin
- Target the harmful toxins produced by pathogens ( diphtheria and tetanus)
- Examples: Diphtheria, tetanus
4. mRNA Vaccines:
- Introduce genetic material to host cells to produce pathogen proteins ( covid 19 vaccine)
- Advantages: Shorter manufacturing time, no pathogen injection
- Disadvantages: Novel approach, unknown long-term effects
mmu