Protein vaccines

In contrast to inactivated vaccines that contain a crude mixture of proteins and other components of pathogens, protein vaccines only contain what is considered the most important bits of the pathogen that are important for protective immunity.

This can be a clean version of a viral or a bacterial protein isolated from pathogens, or from patients.

For instance, for the original vaccine against hepatitis B (a serious liver infection caused by the hepatitis B virus), scientists had to isolate viral proteins from the blood of patients.

The far more elegant version nowadays is to take advantage of recombinant DNA technology. The new version of the hepatitis B vaccine consists of viral proteins that are produced by genetically modified yeast cells carrying the gene for the hepatitis B surface protein.

This way the virus protein can be grown in a safe way and in very large amounts, in massive yeast cultures!