Subunit vaccines are vaccines that use only part of the disease-causing virus.
This strategy is used most often when one part of the virus is responsible for creating disease. The part responsible for creating disease is a protein, which we call the antigen. Subunit vaccines can contain from 1 to 20 antigens,5 that are either taken directly from the virus, or grown in the lab using the virus’ DNA.3 Vaccines made using antigens grown in the lab using the virus’ DNA are called “recombinant subunit vaccines.”
An example of the recombinant subunit vaccine is the hepatitis B virus vaccine. The hepatitis B genes that code for the antigens were inserted into common baker’s yeast. That yeast grew and expressed the genes and produced the antigen protein. Scientists were then able to collect and purify the protein antigen, which was used for the vaccine. Right now, his technique is being used to explore a vaccine against hepatitis C.3
Sometimes whole antigens are broken down further into parts we call epitopes. In order to be used in a vaccine, these parts must be the very specific parts of the antigen that antibodies or T cells recognize and bind to.3
- Subunit vaccines can be given to people with weakened immune systems.
- These vaccines appear to give long-lived immunity
- Since only parts of the virus are used for these vaccines, the risks of reactions are very low.
- Several doses must be given for proper life-long immunity.
Examples of subunit vaccines:
- Hepatitis B
- HPV Vaccine
- The Children’s Hospital of Philadelphia (CHOP). www.chop.edu
- The Centers for Disease Control and Prevention (CDC). www.cdc.gov
- National Institute of Allergy and Infectious Disease. National Institutes of Health. www.niaid.nih.gov
- The history of Vaccines. The College of Physicians of Philadelphia. www.historyofvaccines.org
- Vaccine Healthcare Centers Network. www.vhcinfo.org