THE world鈥檚 deadliest infectious diseases continue to cause mass suffering, especially in poorer nations. But recent developments have increased hopes that a new generation of vaccines will protect against the big killers.
We still don鈥檛 have vaccines for HIV and malaria. Right now, about half of the world鈥檚 population is at risk of , which kills about 1.2 million people a year. .
鈥淲e have been struggling to use traditional vaccine-development approaches with these big pathogens,鈥� says Julie Louise Gerberding, president of the vaccine division at Merck and former director of the .
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HIV and the malaria parasites are unusually complex. Traditional methods of vaccine development, such as rendering a pathogen harmless and injecting it, do not work. For example, the most dangerous malaria parasite, Plasmodium falciparum, has a variable genome and so variable antigens. 鈥淓ach surface protein might come in 50 flavours, and the organisms will pick and choose which of those 50 options it wants to express at any given time,鈥� says Margaret Ackerman of Dartmouth College in Hanover, New Hampshire.
HIV is similarly difficult to target. 鈥淭he problem with HIV is that it is an extraordinarily hypervariable virus,鈥� says , a vaccinologist at the Mayo Clinic in Rochester, Minnesota. 鈥淲ithin minutes, it鈥檚 mutating and changing, so that makes it a very, very difficult virus to make a vaccine against. HIV is also able to evade attack by hiding inside a person鈥檚 immune cells. 鈥淭he immune system doesn鈥檛 realise there鈥檚 a foreign invader,鈥� says Poland.
Daunting though it is, there are reasons for optimism. For one thing, researchers are focusing on groups of people who appear to stay healthy after being infected with HIV or malaria. Learning which genetic factors offer protection could help in making better vaccines, says Ackerman. 鈥淚f we can find people who have generated their own immunity in various ways, we could make a vaccine that could recapitulate this response,鈥� she says.
In addition, says Poland, funding has increased. 鈥淯ntil recently, no company was likely to expend resources to build a vaccine that the affected country couldn鈥檛 even afford,鈥� he says. 鈥淣ow that鈥檚 changed because the pharmaceutical companies have donated money, and the has poured billions in.鈥�
Vaccinologists are starting to see some successes. In 2011, the results of a clinical trial of a malaria vaccine called RTS,S found that it protected about half of the 6000 children who received it. The trial, which is still in progress, is the result of a collaboration between GSK, the and a number of research institutes around the world.
Such international partnerships are providing an additional boost to vaccine development, says Gerberding. 鈥淚t鈥檚 not just a matter of the genetic capabilities we have,鈥� she says. 鈥淭here isn鈥檛 just innovation in the basic sciences 鈥� there is also innovation in how we are collaborating.鈥�
In 2009, researchers at the reported that, for the first time, an HIV vaccine candidate appeared to reduce a person鈥檚 risk of infection by around 31 per cent. 鈥淭hese were small trials, but nonetheless the first hints of some progress,鈥� says Poland.
鈥淧eople are getting very excited about the prospect of an HIV vaccine,鈥� according to Ackerman. 鈥淣ow is a fantastic time to get involved in the research.鈥�
聯People are getting excited about the prospect of an HIV vaccine. Now is a fantastic time to get involved聰
