New adjuvants helping vaccines work better

Gavin Painter (left) and Phil Rendle use IRL's recently upgraded 500MHZ spectrometer to analyse adjuvant samples.

In the past, the emphasis has been on preventing infectious diseases. Now researchers are looking to extend vaccination to not only preventing, but also treating, a wide range of diseases.

Industrial Research’s Manager for Carbohydrate Chemistry, Richard Furneaux, says that this is a promising new area of R&D for his team – developing compounds that can increase the effectiveness of vaccines.

The term “vaccine” originates with Edward Jenner and his 1796 vaccine against smallpox, using the related but milder cowpox virus.

In the intervening centuries, a whole range of vaccines has been developed to protect people and animals against infectious diseases by artificially inducing the body’s immune system to recognise the infectious agent by introducing a foreign “antigen”.

Jenner used live virus in his original vaccine, taken direct from the pustules of a young cowpox sufferer. Today, vaccines are more sophisticated. Researchers use an organism that has been killed or modified in some way, or just part of one, so the vaccine carries little risk of causing illness but will still trigger the body’s immune defences.

But because the antigen is a weakened version of the original organism, these modern vaccines need help to ensure a good immune response and that help comes in the form of additives known as adjuvants.

The most widely used adjuvants in modern day vaccines are mineral salts and were first used in the 1950s in the Salk poliomyelitis vaccine. With the potential uses for vaccines expanding, Richard Furneaux says new adjuvants that are potent, non-toxic, watersoluble, biodegradable and stable are keenly sought after by the pharmaceutical industry.

Now IRL science teams led by Gavin Painter and Phil Rendle have discovered two new compounds they believe have the potential to be effective adjuvants for vaccines.

One is found in a common bacteria and works by what is known as cell-mediated immunity.

“This is where T-cells bind to the surface of other cells that display the antigen and trigger a response rather than encouraging the production of antibodies, which is the case with most adjuvants currently in use,” Gavin Painter says.

The other candidate is derived from plants and Phil Rendle says his team, working in conjunction with Otago University’s School of Pharmacy, has developed a synthetic version that shows potential as an activator of the immune system and also has low toxicity.

“An effective adjuvant can mean a cheaper vaccine since less of the expensive active ingredient needs to be included to get a response. It can also be vital where vaccines are in short supply – the better the adjuvant at provoking an immune response, the further the limited vaccine stock will go,” he says.

“New forms of adjuvants also have the potential to resurrect vaccines that may have failed in prior trials.”

But Richard Furneaux believes the biggest demand will come as the applications for vaccines broadens.

“In future, doctors could be administering a vaccine for diseases such as cancers and autoimmune diseases and for chronic diseases where an effective drug has eluded medical researchers. A vaccine could also be the answer for widespread human diseases such as Tb or malaria – the scourge of many developing nations – where conventional drug treatments are unaffordable or treatment demands strict dosage regimes if the drug is to be effective.”