Which type of vaccine contains whole viruses and requires a mixture of freeze-dried material with a sterile diluent?

The type of vaccine that contains whole viruses and requires a mixture of freeze-dried material with a sterile diluent is a modified-live vaccine. Modified-live vaccines are created by altering the live virus to reduce its virulence while still allowing it to replicate. This modification stimulates an immune response similar to that of a natural infection, providing immunity without causing disease in the host.

When these vaccines are stored, they are often freeze-dried to preserve their integrity and efficacy. To use them, a sterile diluent is mixed with the freeze-dried vaccine to reconstitute it into a form that can be administered to animals. This process ensures that the vaccine remains effective and capable of inducing the necessary immune response.

In contrast, live vaccines typically retain their virulence and do not require freeze-drying, while subunit vaccines contain only parts of the virus and do not involve whole viruses. Toxoid vaccines are made from inactivated toxins rather than viruses. Each of these other vaccine types has distinct characteristics and uses that differentiate them from modified-live vaccines.