Malaria vaccine
16 April 2005
A new malaria vaccine has generated complete and long-lasting protection against experimental malaria infection.
The trials have been carried out by Professor Adrian Hill and colleagues at the Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, who have pioneered the use of 'prime–boost' vaccination. In this approach, a two-stage vaccine-delivery programme is used to drive powerful cell-based immune responses (those based on T cells, as opposed to B-cell-based antibody responses).
The original prime–boost technique used a DNA vaccine for the 'priming' phase and a virus-based approach for the 'boost'. In their latest trials, the Oxford team replaced the DNA vaccine with a second virus-based construct, based on an attenuated avian poxvirus. The work was a collaboration with Michael Skinner’s group at the Institute for Animal Health.
Although responses varied, this combination could provide high levels of protection: two protected volunteers showed memory T cell responses six months later and one was still resistant to infection 20 months after vaccination – the longest-lasting protection yet seen against malaria.
Further studies on larger groups are now in the pipeline. The real test will be, however, how well these vaccines cope in protecting against infection and disease in endemic areas. Following promising phase 1 trials in Kenyan children, a phase 2b efficacy trial has recently been initiated at Kilifi by Wellcome research fellow Philip Bejon working with Kevin Marsh's group.
See also
- Malaria more common than first thought (News: 11 March, 2005)
- Malaria website