Potato Vaccine Offers Hope Against Hepatitis

A hepatitis vaccine grown in genetically engineered potatoes seemed to protect most people who ate them, researchers reported on Monday.

About 60 percent of the volunteers who ate the biggest dose of potatoes showed an immune response that should protect against infection with the hepatitis B virus, Charles Arntzen of Arizona State University and colleagues reported. They hope to develop the vaccine into something that could be used in developing nations, where most cases of hepatitis B are reported. “There is an urgent need to make oral vaccines available in poorer countries of the world where infectious diseases are still the primary cause of death,” said Yasmin Thanavala, an immunologist at the Roswell Park Cancer Institute in New York, who helped to lead the study. The researchers tested 42 volunteers, all of whom had been vaccinated against hepatitis B already using a commercially available shot. They all ate pieces of raw potato, some of which contained a protein from the hepatitis B virus that is known to stimulate an immune system response. Antibodies against hepatitis rose in more than 60 percent of the volunteers who ate three pieces of the gene-engineered potatoes and more than half those who ate two pieces, the researchers reported in the Proceedings of the National Academy of Sciences. About 40 percent of the volunteers did not seem to have the hoped-for immune response to the vaccine, but the researchers noted that commercially available shots also do not always prompt an immune response, either. The hepatitis B shot must be kept refrigerated and it is expensive, meaning it cannot be used in many poor areas. Growing the vaccine in plants such as potatoes might make it more available, the researchers said. And people may be more likely to take an edible vaccine than to get a shot. Members of the team are also working to grow vaccines in bananas, tomatoes and tobacco. “In 1996 it was estimated that some 115 million people were infected with HBV even though a … vaccine isolated from yeast became available a decade earlier,” the researchers wrote. “Global mortality due to this disease is estimated to be 1 million cases per year.” (Source: Reuters Health, February 2005)