Injection of a weakened or mild form of a disease-causing agent to produce immunity


A preparation of killed or weakened microorganisms that is administered to produce or increase immunity to a particular disease


A segment of genetic material that is used as a vehicle to introduce specific genes into cells


The ability to cause rapid and severe disease


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