Hepatitis B Vaccine in Potatoes Shows Promise
Low-Cost Vaccine Can Be Genetically Added to Potatoes
Feb. 14, 2005 -- Could potatoes with a built-in hepatitis B vaccine help save the lives of millions of people worldwide?
It might work, judging by a preliminary study from Yasmin Thanavala, PhD, and colleagues. Thanavala works in the immunology department at Roswell Park Cancer Institute in Buffalo, N.Y.
Every year, hepatitis B kills about a million people worldwide, scientists report in the early edition of Proceedings of the National Academy of Sciences. In 1996, it was estimated that 115 million people around the world were infected with the virus that causes hepatitis B, which can lead to liver cancer.
That's despite the existence of a hepatitis B vaccine. Even in the U.S., hepatitis B vaccination rates fall short of goals. The rates are worse in poorer countries that can't afford the vaccine or lack cold storage sites, which the vaccine requires.
In the U.S., the hepatitis B vaccine is recommended for all children, which includes a series of three shots given between birth and 18 months of age.
Crafting an Edible Hepatitis B Vaccine
Seeking a more affordable solution, researchers genetically modified ordinary potatoes to carry the gene for the hepatitis B surface antigen. The potatoes were then cloned and cultivated.
Forty-two people who had already been vaccinated against hepatitis B volunteered to try the edible vaccine. Some participants were served ordinary potatoes that did not contain the vaccine. Some got the vaccine potatoes just once, eating plain potatoes in the other two sessions. The remaining volunteers ate the vaccine potatoes in three sessions two weeks apart. All the potatoes were eaten raw.
Ten of 16 volunteers who ate three doses of the vaccine-containing potatoes showed a marked increase in their immune response against hepatitis B.
Nine of 17 volunteers who ate the vaccine potatoes only once also had increased immune responses to hepatitis B.
About 40% of the participants who got the vaccine-carrying potatoes didn't show any immune response to hepatitis B. More studies are needed to find out why that happened. Further research must also test the vaccine on people who hadn't been previously vaccinated against hepatitis B, say the researchers.
"We are greatly encouraged," they write. "This prototype study ... gave us a strong and sustained systemic antibody response in 60% of the volunteers who ate the [vaccine-carrying] potatoes."
By curbing hepatitis B, the vaccine could also help combat liver cancer, the fifth most frequent form of cancer worldwide, say the researchers. It's sensible and ethical, they say, to direct scarce resources for the greatest good.
"Give new vaccination strategies for hepatitis B virus a higher priority, especially those that could be implemented very cost-effectively throughout the developing world," they write.