Progress in potato-based vaccine for hepatitis B

US researchers have taken another step towards an oral vaccine for hepatitis B. "For the first time", explains Hugh Mason (Bryce Thompson Institute for Plant Research, Ithaca, NY, USA), "we have shown that mice fed potatoes expressing the hepatitis B surface antigen develop circulating serum antibodies against the antigen".

Mason and his colleagues have been working towards an edible plant vaccine for hepatitis B for nearly a decade. "Such a vaccine would be cheaper to produce and deliver than the existing yeast recombinant vaccine, which is injected intramuscularly", explains Mason. "In developing countries, such as China where there is endemic hepatitis B, a large-scale immunisation programme with the existing vaccine is simply too expensive."

In their current paper, Mason and colleagues describe how mice fed three weekly doses of 5g of raw potato containing 5·5µg of antigen and 10µg of cholera toxin as an adjuvant developed a primary serum antibody response (Nat Biotech 2000; 18: 1167-71). They go on to explain how they have now increased the antigen yield of their potatoes ten fold, an advance that should lead to an increased immune response in future studies. Nevertheless, potatoes are not an ideal source for an oral vaccine, admits Mason. "Raw potato is not very palatable and if we boil it, most of the immunogenicity is lost. We are now looking at tomatoes as an alternative."

William Langridge (Loma Linda University, CA, USA) predicts that the hepatitis B vaccine may be one of the first edible plant vaccines to reach the marketplace, "probably in 2 or 3 years". The clinical trials needed to achieve this will be expensive, he warns, "but it is important that we pursue this second green revolution to help prevent infectious diseases, particularly in developing countries".

Jane Bradbury

ç indietro