Polyvalent recombinant antigens: a new vaccine strategy.

Recombinant DNA technology can be used to produce individual proteins from infectious organisms and these have the potential to be used as subunit vaccines. In many cases however these proteins display a low immunogenicity. One reason for this might be the poor presentation of the antigen to the cells of the immune system. A number of new recombinant DNA approaches are now being tried to improve the production and the presentation of antigens. One method is to use a carrier protein encoded by a retrotransposon of yeast called the Ty element. This protein can be linked to a wide range of viral antigens via the construction of hybrid genes. The fusion proteins assemble in yeast into 60 nm virus-like particles (VLPs) that display the additional antigens on the surface. These hybrid Ty-VLPs are good immunogens even in the absence of adjuvant. Similar approaches to the production of polyvalent particulate antigens involve using carrier proteins derived from hepatitis B and polio viruses.