Viruses & Disease
What two components make up a virus?
Nucleic acids (DNA or RNA) and a protein shell
What is the type of immunity you are born with that provides nonspecific defense?
Innate immunity
What cells mediate adaptive immunity?
Lymphocytes (B and T cells)
What proteins produced by B cells help fight infection?
Antibodies
What is immunity?
Resistance to a given pathogen
Why is a virus considered non-living?
It is not made of cells and lacks metabolism
Name one innate immune barrier.
Physical or chemical barriers (e.g., skin, mucus, stomach acid)
What binds to immune receptors and activates lymphocytes?
Antigens
How many major antibody types exist in blood and lymph?
Five (IgA, IgD, IgE, IgG, IgM)
What happens faster and stronger after a second exposure to a pathogen?
The adaptive immune response
What event did four viral genes help worsen by allowing infection deep into the lungs?
The 1918 flu pandemic
What proteins released by virus-infected cells impede viral replication?
Interferons
Which cells produce antibodies?
B cells
What is neutralization?
Antibodies block the viral binding site, preventing infection
How do vaccines work?
They trigger a primary immune response to create memory cells without causing disease
What destroys lung tissue in severe flu infections?
A massive inflammatory response
What is inflammation designed to do?
Increase blood flow and bring white blood cells to attack pathogens
What two types of cells does an activated B cell divide into?
Plasma cells and memory cells
What is opsonization?
Antibodies tag pathogens so phagocytes can recognize and engulf them
What is herd immunity?
When enough people are vaccinated that even unvaccinated individuals are protected
What is a pathogen?
A disease-causing organism or particle
What white blood cells engulf and digest pathogens in innate immunity?
Phagocytes
What type of immunity targets infected or altered body cells?
Cell-mediated immunity (cytotoxic T cell response)
What is agglutination?
Antibodies clump pathogens together so phagocytes can clear them
What is the difference between antigenic drift and antigenic shift?
Drift = gradual mutations causing small antigen changes
Shift = genetic exchange between viral strains causing major antigen changes