A vaccine which could prevent HIV infection is on the horizon, new research suggests.

Scientists have begun to understand the structure of the virus’s ‘envelope’ which helps it enter human cells. The researchers say the breakthrough is of great value for medical science. The finding provides the most detailed picture yet of the AIDS-causing virus’s complex structure – including parts of the virus that future jabs could mimic to elicit an immune response.

About 34 million people are infected with HIV and although drugs are used to manage many cases, there is currently no vaccine that can prevent new infections. None of the HIV vaccines tested so far have come close to providing adequate protection against the virus. This is because of the challenges posed by the ‘envelope’ protein, which is called Env. Env’s structure is so complex and delicate scientists have found it difficult to get the protein into a form that is suitable for the imaging technique necessary to study it. Professor Andrew Ward, of The Scripps Research Institute (TSRI), explained: ‘It

tends to fall apart, for example, even when it’s on the surface of the virus, so to study it we have to engineer it to be more stable.’

In the study, researchers created a version of Env that has the stability and other properties needed for successful imaging, but that retains virtually all the structures found on Env. Using cutting-edge imaging methods they were then able to study the new Env in minute detail. The study was the first ever of Env, and revealed the envelope’s structure in finer detail than has been reported before. The study for Science Express revealed how Env assembles and undergoes shape changes during infection, and showed how it compares to envelope proteins on other dangerous viruses – such as flu and Ebola.

Professor Ian Wilson, of TSRI, said: ‘Most of the prior structural studies of this envelope complex focused on individual subunits – but we’ve needed the structure of the full complex to properly define the sites of vulnerability that could be targeted, for example with a vaccine.’


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