Overview of the Immune System and Comparative Immunology

Vocabulary flashcards covering core immune system concepts, comparative immunity across taxa, major historical milestones, and key definitions from the lecture.

Innate Immunity

A broad set of disease resistance mechanisms present in an organism that are not specific to particular pathogens.

Adaptive Immunity

A highly specific disease resistance mechanism found only in vertebrates that displays memory and targeted recognition of specific pathogens.

Host

An organism or species that harbors a pathogen.

Red Queen Hypothesis

An evolutionary theory proposed by Leigh van Valen stating that organisms must continuously adapt and evolve to survive against co-evolving antagonist species, parasites, or pathogens.

Antigenic Variation

An evolutionary defense mechanism where pathogens alter their surface antigens so host memory cells and antibodies can no longer recognize them.

Thucydides

An ancient Greek historian who observed during the plague of Athens (430 BC) that individuals who recovered from the disease could nurse the sick without becoming reinfected.

Variolation

An early method of immunization practiced in 15th-century China and Turkey that involved introducing dried smallpox pustule crusts into the skin or nasal passages to induce immunity.

Edward Jenner

An English physician who in 1798 demonstrated that inoculating humans with cowpox crusts conferred protection against smallpox, establishing the foundation of modern vaccination.

Louis Pasteur

A French scientist who discovered that attenuated bacterial strains could prevent disease, coined the term "vaccine," and developed vaccines for chicken cholera and rabies.

Attenuation

The process of reducing or weakening the virulence of a pathogen, rendering it safe for use in vaccines.

Pasteur's Chicken Cholera Experiment

A pivotal 1879 experiment demonstrating that chickens injected with an aged, attenuated culture of Pasteurella multocida survived and became resistant to subsequent lethal doses of fresh virulent cultures.

Julian H. Lewis

An American pathologist (1891–1989) who published scientific research challenging race-based blood-typing theories and refuting the idea of a "superior" race.

Winifred M. Ashby

A scientist (1879–1975) who developed the Ashby method to measure red blood cell lifespan, significantly improving blood transfusion safety and storage practices during World War II.

Variola Major

The viral pathogen responsible for smallpox, characterized by a 30% mortality rate, which was globally eradicated in 1980 through widespread vaccination.

Herd Immunity

The protection provided to a population when a sufficient percentage of individuals are immune to an infectious agent, thereby reducing transmission and protecting unimmunized or immunocompromised individuals.

Comparative Immune Strategies across Taxa

The spectrum of host defense mechanisms across biological kingdoms, ranging from CRISPR-Cas in unicellular organisms, physical and NLR defenses in plants and fungi, to adaptive immunity unique to jawed vertebrates.