New innoculation offers affordable protection for children in developing countries.
Children in the UK are routinely immunised against Haemophilus influenzae b (Hib), which causes meningitis and pneumonia, but there are literally billions of children in the developing world that cannot afford the vaccine. As a result, more than half a million children die from Hib infection each year. Cuban researchers have now presented a novel, fully synthetic vaccine that can be produced much more cheaply and thus will reach all parts of the world. Coincidentally, it is the first fully synthetic vaccine to succeed in all clinical trials.
Over the last two decades, Cuba has responded to the lack of affordable drugs by investing heavily in biotechnology. As part of this effort, the laboratory of Vicente Verez-Bencomo at the University of Havana set out to produce an alternative to the original Hib vaccine, which Verez describes as ’only a solution for rich countries’. The key challenges were to produce the characteristic oligosaccharides found on the cell surface of the pathogen, and to find a way of presenting them to the immune system that would secure a strong, specific, and long-lasting immunity against the pathogen.
In collaboration with Canadian chemist Ren? Roy and colleagues from several of the major Cuban biotech research centres (including the Centre for Genetic Engineering and Biotechnology, Havana), Verez’s group developed a novel synthetic route to the crucial oligosaccharides, suitable for large-scale production. By the end of the 1990s, they could produce the sugars, couple them to a human serum protein, and show that they triggered the desired immune response. However, to compete with the long-term effect of the existing vaccine, the researchers had to couple the sugars to a protein that stimulated the immune system more efficiently. Tetanus toxoid (TT) protein turned out to be the right molecule for the job.
The synthetic glycoconjugate went through all the required toxicity tests and clinical trials performing at least as well as the commercial vaccine. ’We have transferred production to the Cuban biotech companies,’ says Verez. ’They are going to produce one million doses by the end of the year.’
V Verez-Bencomo et al, Science 2004, 305, 522