Trials begin for 'garden variety' hepatitis B vaccine

Can eating potatoes protect humans against hepatitis B?

Roswell Park Cancer Institute (RPCI) and the Boyce Thompson Institute (BTI) at Cornell University began clinical trials July 7 at RPCI to test the safety and immunogenicity of the world's first potential oral vaccine against the hepatitis B virus. The vaccine will be delivered by eating potatoes genetically designed to contain the vaccine.

More than two billion people worldwide are affected by the hepatitis B virus, a leading cause of liver cancer and the cause of more than a million deaths annually. Although an effective vaccine is available to prevent hepatitis B, developing nations cannot afford it. It must be imported and refrigerated at a cost of $100 to $150 per person, and requires three injections which prohibits mass immunization in Third World countries.

The trial that began this month is the culmination of several years of collaborative preclinical work by Yasmin Thanavala, UB research assistant professor of microbiology, and professor and cancer research scientist in the Department of Immunology at RPCI; Charles Arntzen, president and CEO of BTI and adjunct professor of biological sciences at Cornell University, and Hugh Mason, BTI assistant research scientist and assistant professor of plant biology at Cornell. The program is funded primarily by the National Institutes of Allergy and Infectious Diseases, part of the National Institutes of Health (NIH).

In previous pilot studies, researchers inserted DNA extracted from hepatitis B virus into tobacco leaves. An immunologically important protein antigen known as HBsAG was partially purified and injected into mice-eliciting the same immune responses in mice as that obtained by the commercial vaccine. More recently, the researchers produced this vital protein in potatoes, which are edible, making them more suitable for testing oral vaccines.

In the current placebo-controlled, double-blind, Phase I study, health-care workers who previously responded to a licensed, injectable vaccine receive an oral booster dose. This dose is delivered by a sample of transgenic potato that expresses the hepatitis B surface antigen. BTI generated the potatoes for the clinical trial with financial support provided by Axis Genetics, plc, of Cambridge, UK.

The clinical trial is coordinated by Thanavala and Martin Mahoney, UB assistant professor of family medicine and director of the RPCI Employee Health Clinic. They will share responsibility for laboratory testing and clinical assessment, respectively.

"We are very pleased to be taking the next logical step with this research," said Thanavala. "The continued support of my basic research by the NIH and the World Health Organization, along with the recent collaboration with Axis Genetics, offers us a novel way to impact public health and control hepatitis B worldwide."

Research with genetically engineered foods opens up limitless possibilities for delivering vaccines, not only for hepatitis B, but for such diseases as malaria and leprosy.