NOVA Online (see text links below)
Making Vaccines
Subunit vaccine: hepatitis B

Hepatitis step 1 Step 1
Use the tweezers to pull out a segment of DNA from the hepatitis B virus.

  A subunit vaccine makes use of just a small portion of a pathogen. For a virus, the vaccine can contain just a piece of the protein coat that surrounds the virus's DNA (or RNA). Even small portion of a virus is sometimes enough to stimulate an immune response in the body.

There are several ways to produce a vaccine for hepatitis B vaccine. For your vaccine, you'll use genetic engineering techniques.

Hepatitis step 2 Step 2
Add the segment of DNA to the DNA of a yeast cell (which is in the yeast culture).

  A segment of the virus's DNA is responsible for the production of the virus's protein coat. You will add this segment to the DNA within a yeast cell.

The yeast cell, as it grows, will "read" the viral DNA incorporated in its own DNA and produce the protein that makes up the protein coat of hepatitis B.

Hepatitis step 3 Step 3
Use the purifier to isolate the hepatitis B antigen produced by the yeast cells.

  The vaccine, once administered, will stimulate the immune system to attack the antigen (i.e., the protein coat). Then, if the inoculated person is later exposed to the virus, the immune system will quickly respond to the invader and eliminate it before it has a chance to spread widely.

To finish making the vaccine, you need to separate the proteins from the yeast cells.

Hepatitis step 4 Step 4
Fill the syringe with the purified hepatitis B antigen.

  The isolated hepatitis B protein, produced by the yeast cells, contains none of the viral DNA that makes hepatitis B harmful. Therefore, there is no possibility of it causing the disease.

Hepatitis done Done
The hepatitis B vaccine is complete.

Select another pathogen.

  Congratulations. You have produced a subunit vaccine for hepatitis B.

Another example in the subunit category is the anthrax vaccine approved in the U.S. (The countries of the former Soviet Union have an attenuated version of the vaccine.) The U.S. vaccine is currently administered to military personnel.

Smallpox icon
Similar-pathogen vaccine:
smallpox virus
  Measles icon
Attenuated vaccine:
measles virus
  Polio icon
Killed vaccine:
polio virus
Tetanus icon
Toxoid vaccine:
  Hepatitis icon
Subunit vaccine:
hepatitis B
  HIV icon
Naked-DNA vaccine:

Printer-Friendly Format   Feedback

History of Biowarfare | Future Germ Defenses
Interviews with Biowarriors | Global Guide to Bioweapons | Making Vaccines
Resources | Teacher's Guide | Transcript | Site Map | Bioterror Home

Search | Site Map | Previously Featured | Schedule | Feedback | Teachers | Shop
Join Us/E-Mail | About NOVA | Editor's Picks | Watch NOVAs online | To print
PBS Online | NOVA Online | WGBH

© | Updated November 2001
Shop Teachers Feedback Schedule Previously Featured Site Map Search NOVA Home