Toxin's key to more potent vaccines

A poison may in the future become the basis of vaccines used to treat or to protect against viral and auto-immune diseases and, eventually, some forms of cancer.

Research at Warwick University, UK, has shown that ricin's ability to penetrate deep into human cells can be used to deliver peptides and proteins, the raw materials of vaccines, to the hard-to-reach targets which must be hit if the immune system is to be stimulated to attack cancer and some other diseases in the most effective way.

The next step will be to make experimental vaccines which work in the same way.

Molecules of ricin absorbed by human cells find their way to ribosomes, the particles inside cells where new proteins are manufactured, and destroy the ribosomes.

This renders the cell unable to produce the essential components of the human body, fresh supplies of which are constantly needed as they become used up or worn out.

Professor Mike Lord and Dr Lynne Roberts of the University of Warwick have shown that when peptide (portions of proteins) from influenza virus are attached to ricin molecules, they are able to stimulate a cell-mediated immune response.

The purpose of this experiment was to use well-understood antigens, the influenza peptides, to prove that it is, in principle, possible to link antigens to ricin to produce vaccines which will stimulate cell-mediated immune responses against harmful foreign proteins.

The proof that this is possible has opened the way towards vaccines which, if all goes well, will be able to stimulate a vaccinated person's immune system to attack and destroy cells containing foreign proteins, produced by viruses or cancer cells, which cannot be used in conventional vaccines because the proteins do not stimulate antibody production.

University of Warwick website