IMMUNOLOGY

Innate Immunity

Built-in body defenses operating through natural processes.

Adaptive Immunity

More specific immunity that adapts throughout a lifetime.

Inflammatory Response

Vascular and cellular response to tissue injury or infection to eliminate pathogens.

Vasodilation (Inflammation)

Increased blood flow leading to redness and heat.

Vascular Permeability (Inflammation)

Vessel leakiness leading to swelling and edema.

Chemotaxis (Inflammation)

Recruitment of phagocytic white blood cells like neutrophils and macrophages to infection sites.

Humoral Immunity

B-lymphocytes produce and secrete antigen-specific antibodies into blood and bodily fluids.

Cell-Mediated Immunity

T-lymphocytes coordinate responses and kill infected cells using cytotoxic and helper T cells.

Autoimmunity

Immune system misidentifies body tissues as foreign and attacks host cells.

Immunodeficiency

Impairment of immune components leading to increased vulnerability to infections.

Immunological Memory

Capacity of the adaptive immune system to remember specific antigens and respond rapidly later.

Active Immunity

Immunity where the body produces its own antibodies and memory cells.

Passive Immunity

Temporary protection acquired via pre-formed antibodies transferred from an outside source.

Naturally Acquired Active Immunity

Immunity developed after recovery from a natural infection.

Artificially Acquired Active Immunity

Immunity developed through vaccination.

Naturally Acquired Passive Immunity

Maternal antibodies transferred across the placenta or through breast milk.

Artificially Acquired Passive Immunity

Injection of monoclonal antibodies or immune globulin serum.

Goals of Vaccination

Long-term protective immunological memory without clinical disease, creating herd immunity.

Qualities of a Good Vaccine

Safe, minimal side effects, highly immunogenic, long-lasting, stable, affordable, and accessible.

Live Attenuated Vaccines

Uses a weakened form of a live pathogen (e.g., MMR, Yellow Fever).

Inactivated/Killed Vaccines

Uses an inactivated pathogen to trigger an immune response (e.g., Polio IPV, Rabies).

Subunit/Recombinant/Conjugate Vaccines

Uses specific purified antigens or proteins (e.g., HPV, Hepatitis B, Hib).

Toxoid Vaccines

Uses inactivated bacterial toxins (e.g., Tetanus, Diphtheria).

mRNA / Viral Vector Vaccines

Delivers genetic material instructing cells to express target proteins (e.g., COVID-19 mRNA).

Smallpox Eradication

Eradicated globally in 1980 through targeted surveillance and ring-vaccination.

Polio Eradication Initiative

Achieved near-global eradication through oral and inactivated polio vaccine initiatives.

Anti-bodies

produced by B-lymphocytes, ability to perform depends on shape of antigen

IgG antibodies

main, can transfer to placenta, declines until baby produces its own antibodies

IgA antibodies

secreted antibodies; found in saliva, tears, and mucous membranes

IgE antibodies

epithelial surfaces, protects against larger pathogens, causes asthma when binds to mast cells -> release of mediators

Disease triangle

1. Agent: The biological pathogen (virus, bacterium, parasite).

2. Host: The organism harboring the disease.

3. Environment: External factors bringing agent and host together (climate, sanitation, vector breeding sites).

foodborne/waterborne illnesses

Examples: Salmonella, E. coli, Vibrio cholerae, Giardia, Norovirus.

Transmission: Fecal-oral route via ingestion of contaminated food or untreated water sources, poor hand hygiene, or improper food storage/handling.

Antibiotic resistance

Ability of bacteria to resist the lethal or inhibitory effects of antibiotics.

Contributing Factors: Overprescribing antibiotics, incomplete courses of treatment, agricultural/livestock overuse, poor infection control in healthcare settings, and lack of new antibiotic development.

Combating Strategies: Antibiotic stewardship programs, development of novel therapeutics, improved infection prevention/hygiene, and restricting non-therapeutic antibiotic use in agriculture.

bioterrorism

2001 Anthrax (Bacillus anthracis) spores mailed through US postal service; historical contamination of water supplies or food sources.

Category A agents

High priority agents pose highest risk to national security (easily disseminated/transmitted, high mortality, e.g., Anthrax, Botulism, Plague, Smallpox, Tularemia, Viral Hemorrhagic Fevers).

Category B agents

Moderately easy to disseminate, moderate morbidity and low mortality (e.g., Salmonella, Ricin toxin).

Category C agents

Emerging pathogens engineered or mass-produced due to availability and ease of dissemination (e.g., Hantavirus, Nipah virus).