Vaccination
Injection of a weakened or mild form of a disease-causing agent to produce immunity.
Vaccine
A preparation of killed or weakened microorganisms that is administered to produce or increase immunity to a particular disease.
Vector
A segment of genetic material that is used as a vehicle to introduce specific genes into cells.
Virulence
The ability to cause rapid and severe disease.
Virus
A microscopic particle that is made up of genetic material (either DNA or RNA) and protein that can replicate only inside living cells.
Virus-like particle
A particle assembled from multiple copies of the capsid protein that, like a virus, can produce an immune response, but unlike a virus, is not infectious because it does not contain genetic material.