20 december 2011

New malaria vaccine may stop deadly parasites in their tracks

Source: Wellcome Trust

Health

Mosquito

A new malaria vaccine with the potential to neutralise all strains of the most deadly species of malaria parasite has been developed by an Oxford University-led team.

The scientists from the Jenner Institute at the University of Oxford have shown that their vaccine induces an antibody response in animal models that is capable of neutralising all the strains they tested of the malaria parasite Plasmodium falciparum.

The group led by Dr Simon Draper, with colleagues from the Wellcome Trust Sanger Institute and the Kenyan Medical Research Institute-Wellcome Trust Programme in Kilifi, Kenya, have published their findings in the journal Nature Communications.

The results add to a key discovery reported last month. Scientists at the Wellcome Trust Sanger Institute identified a potential ‘Achilles’ heel’ in the malaria parasite that could hold significant promise for vaccine development.

This is an important step towards developing a much-needed vaccine against one of the world’s major killers.

Dr Sandy Douglas

Their research published in the journal Nature showed that the P. falciparum parasite relies on a single protein – the antigen RH5 – to ‘unlock’ the doorway for the parasite to enter red blood cells. Once there, it grows and replicates, causing potentially life-threatening disease.

Lead researcher Dr Sandy Douglas of the University of Oxford says: ‘We have created a vaccine that confirms the recent discovery relating to the biology of RH5, given it can generate an immune response in animal models capable of neutralising many – and potentially all – strains of the P. falciparum parasite, the deadliest species of malaria parasite. This is an important step towards developing a much-needed vaccine against one of the world’s major killers.’

Malaria killed around 800,000 people in 2009, mainly young children and pregnant women. It is caused by parasites that are carried by mosquitoes. The most deadly form, P. falciparum, is responsible for nine out of ten deaths from malaria.

Vaccination is likely to be the most cost-effective way of protecting people against malaria. However, no licensed vaccine is currently available. While one vaccine is achieving promising but incomplete levels of protection in clinical trials in Africa, scientists believe a new and more effective vaccine will be required to eradicate the disease.

Professor Adrian Hill, director of the Jenner Institute at the University of Oxford, says: ‘Vaccines against malaria are notoriously difficult to develop because the parasites’ antigens – the target of vaccines – tend to be genetically so diverse. The RH5 antigen doesn’t show this diversity, making it a particularly good target for a vaccine to exploit. Our next step will be to begin safety tests of this vaccine. If these prove successful, we could see clinical trials in patients beginning within the next two to three years.’

The research was funded by the Wellcome Trust, with other support from organisations including the UK Medical Research Council.