Prevention: How Vaccines Work

Vaccines prevent disease by creating antibodies to neutralize the causative virus, bacteria or toxin.The part of the vaccine that trains the immune system into making the appropriate antibodies is called an antigen. Antigens may be introduced by:

Modified Live Vaccines

Modified live vaccines contain an attenuated or weakened version of a disease agent. These vaccines create a mild form of the disease that stimulates a natural immune response. Modified live vaccines are effective but can negatively impact the health of the animal.

Killed Vaccines

Killed vaccines contain an inactivated disease-causing agent. These vaccines are designed to create antibodies without the negative effects of infection so are generally considered to be safe. However, during the inactivation process, some of the surface antigens needed to create the desired antibodies may be destroyed thus reducing their effectiveness.

Subunit Vaccines

Subunit vaccines use only the necessary parts of the virus to stimulate immunity.  Unlike modified live vaccines, subunit vaccines stimulate the immune system to prevent disease without stressing the animal. And unlike killed vaccines, subunit vaccines do a better job of disease prevention as they only contain concentrated amounts of the target antigen. These qualities make subunit vaccines both safe and effective. Dow AgroSciences plant-cell-produced vaccines are a new type of subunit vaccines.