Possible Potato Vaccine for Hepatitis B

W A S H I N G T O N, Oct. 30, 2000 -- Researchers said todaythey had taken a step closer to making an edible vaccineagainst hepatitis B, a virus that infects billions of peopleand that can lead to liver disease, cancer and even death.

They said they had genetically engineered a potato thatproduces the vaccine in its flesh.

“The hepatitis B vaccine currently in use is ... based onan antigen produced in yeast. We have shown we can produce thesame antigen in plants,” said Hugh Mason, who ledthe research at Cornell University’s Boyce Thompson Institutefor Plant Research, said in a telephone interview.

Antigens are proteins on a virus or bacteria that stimulatethe body to produce antibodies, which in turn flag an invaderfor destruction by immune cells.

For years scientists have known that a protein known asHBsAg can produce this response, and they can take the gene forthis viral protein, insert it into yeast, which then grow andproduce a protein that can be used to make vaccine.

But it is not cheap and it has to be refrigerated, makingdistribution in remote areas difficult. “Most developingcountries just can’t afford it,” Mason said.

Tremendous Need for Vaccine

With an estimated two billion people infected withhepatitis B, the need for a vaccine is tremendous.

“What we want to try to do is produce this material inplants and show there potential for delivery by just eating theplant material. Our study with mice suggested this could be afeasible strategy.”

Mason’s team genetically engineered potatoes to produce theprotein and then fed the raw potatoes to mice. The miceproduced antibodies against hepatitis B, the researchers wrotein the journal Nature Biotechnology.

Mason said further, as-yet unpublished studies in mice showthey can increase the power of the vaccine, and it might beused as a booster for the injected vaccine. “Obviously there isgoing to be a difference between humans and mice,” Mason said.

A More Robust Response

“We do think it’s likely that we will need a more robustresponse.”

The Cornell researchers have also done a small study inhuman volunteers, but the British-based company they wereworking with, Axis Genetics Plc, went out of business a yearago amid European fears about genetic work. He also thinks that freshvegetableswill not be used, but perhaps a processed version — maybe evena candy bar that would be stable and easy to distribute.

One big hurdle will be getting a commercial partner, Dr.Julian Ma of Guy’s Hospital in London said in a published commentary.

“Apart from a handful of small biotechnology companies,industry has been slow to invest in this field for a variety ofreasons,” Ma wrote in NatureBiotechnology.

“For certain, the commercialization of plant vaccines willrequire an unusual and imaginative collaboration between theagricultural and pharmaceutical industries. Another concern isthe potential for commercial profit.”

Ma noted that the current, injected hepatitis B vaccine hadgenerated profits of $1 billion a year. “It is extremelyunlikely that a plant-derived alternative could come even closeto matching this commercial success,” Ma wrote.

The only current oral vaccine is for polio.