The search for a vaccine against the highly complex and highly contagious HIV virus has so far proved elusive. Three of the last four large-scale trials have not succeeded. But from each failure, vital lessons have been learned.

And now some of these lessons are being applied to a new vaccine trial which will be conducted in three centres in Kigali, Uganda, Nairobi, Kenya, and London.

The trial, being run by the International Aids Vaccine Initiative (IAVI), has already begun recruiting volunteers in Kigali and will start here soon through the St Stephen’s Centre at the Chelsea and Westminster Hospital in West London.

Two potential Aids vaccines will be used following previous trials which have shown quite simply that two is better than one.

The first, new vaccine is called SeV-G and is a combination of a weakened Sendai virus, which a flu-like disease affecting rats, which will carry parts of the HIV virus into the body.

It targets mucosal tissue which is where the HIV virus establishes a foothold within days of infection. It is also, like the HIV virus, capable of replicating itself, which scientists think is important for achieving a longer lasting immune response.

This will be delivered through a nasal spray, which has the added of advantage of doing away with needles.

The second is the Ad35-GRIN, which is related to respiratory infection viruses. This has already been shown to be safe in three other IAVI-sponsored trials in Africa and North America and does generate an immune response.

The aim is to prevent infection and then if the virus does enter the body, it can be killed fast.

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This Phase 1 trials – with the rather prosaic title S001 – will use the two vaccines together in the hope – or even expectation – or producing a stronger, longer lasting immune response.

The trials will initially recruit 64 healthy volunteers across the three countries, aged between 18 and 50, all at low risk of contracting the virus and all HIV negative. They want to be able to measure their immune responses to the two vaccines.

This is only a phase 1 trial although seven years has been spent on testing the safety of the vaccines. And it could be five to 10 years before researchers know if it is going to work.

But there is enormous optimism in the world of Aids research. After years of disappointments and failures, scientists are again talking not just about vaccines but even a cure.

Time is, of course, of the essence. In 2011, there were 7,000 new HIV infections every day and 34 million people worldwide living with the virus.

Dr Jill Gilmour, head of the Human Immunology Laboratory, based at Chelsea and Westminster Hospital, said that for every three people given anti-retroviral drugs, there are five people newly infected.

“We need a vaccine that recognises the multiple strains of of the virus. But we also believe that if a rare number of people are able to develop an immune response that can control infection, which they do, then so can we,” Dr Gilmour said.

The Terrence Higgins Trust Aids charity said that while any research is welcomed, this is early days and it still does not remove the need for better testing and the use of condoms as well getting anti-retroviral drugs to as many people who need them as possible.

However, recently, hopes have been raised with the announcement of the Mississipi baby who was found to have been functionally cured by receiving antiretroviral drugs at birth and the VISCONTI group of 12 patients in Paris who also appear to be functionally cured – that is, the virus is there but undetectable and having no affect on their health and not capable of being transmitted.

And there is ‘Towards and HIV Cure’, which is a global initiative to do just as it says – one day eradicate the world of this disease.

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