Fresh Hope For Malaria Vaccine By Piggy-Backing It Onto Viruses
There is currently no effective vaccine against malaria, but now an international collaboration of scientists funded by the Medical Research Council and the Wellcome Trust in the UK are moving into phase 1 trials for a new vaccine following success in animals and the lab using a recombinant adenovirus-poxvirus immunisation regime. Their research, led by MRC scientist Dr Simon Draper and Professor Adrian Hill at Oxford University is published in Nature Medicine.
Malaria infects hundreds of millions of people every year worldwide; between 2 and 3 million infections result in death, most of these in children. So far attempts to devise a vaccine have hinged largely on using proteins in adjuvants, chemicals designed to amplify the body's immune response to the vaccines. These have had limited success against difficult diseases such as blood-stage malaria, the stage of the disease which results in clinical illness and can be fatal.
Microscopy image of malaria parasites in the blood
The new method has proved completely protective in mice and has been shown to reduce the growth of human malaria in laboratory tests by between 70 and 85 percent, depending on the strain. It involves using two viruses, an optimised adenovirus (the common cold) and 8 weeks later the pox virus (used to eradicate smallpox and in many vaccines since), both of which are genetically engineered to express a malaria protein. The results were startling. Not only did the vaccines generate a strong T-cell response, as might have been predicted for these virus technologies, it also induced a very strong antigen-specific antibody response. This means it created large numbers of antibodies targeting the malaria protein specifically.
Dr Simon Draper said "This work is the result of a slow iterative process. We had to modify the viruses, for example by improving the gene promoter in the adenovirus, and optimise the time interval between the prime vaccination and the booster jab. In the end however, the results were startling, and we could use these viruses to induce very high levels of antibodies for the first time. These data have allowed us to obtain a grant from the MRC to move into phase 1 clinical trials on healthy volunteers starting next year. In the meantime we are finalising and producing the human vaccine to be used."
Although there are other malaria vaccine trials ongoing throughout the world, this is the first which will use this delivery method to target blood-stage malaria, rather than recombinant proteins in proprietary adjuvants.
Dr Draper added: "One of the benefits of using viruses is that they do not require a chemical adjuvant, and they are somewhat easier to grow which may facilitate mass production. Clearly we need every weapon we can muster in the global fight against malaria."
Original research paper: Effective induction of high-titer antibodies by viral vector vaccines by SJ Draper et al is published in the journal Nature Medicine.
Medical Research Council
Proaspete de speranþã pentru a malariei Vaccin Prin purceluº-Back Este Onto Virusi - Fresh Hope For Malaria Vaccine By Piggy-Backing It Onto Viruses - articole medicale engleza - startsanatate