Monkey vaccine offers new hope to AIDS patients

Posted on May 12, 2011

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I’ve found it very difficult to write this week. The intention has been there but there’s been no will. I’ve just finished my end of year exams which monopolised most of my time cramming and has left me feeling brain drained and I’ve also had a family funeral – my dear uncle died of cancer – I’ll miss him tremendously. May he rest in peace.

As a child I wanted to grow up to be research scientist and help to find a cure for diseases such as cancer; HIV; lupus. I’ve lost loved ones to all of these illnesses. Although that dream is unlikely to be achieved by me, I sincerely hope there’ll be a medical breakthrough in my lifetime so that other people don’t have to go through the heartache I’ve seen and experienced.

Animal testing is a hugely controversial area and will no doubt divide opinion, even in the scientific world. Putting other living creatures through pain and suffering is something that does not sit well with me. I am aware that many of the drugs we have on the market today could not have been made possible without these trials. However I hope with scientific advancement there’ll be alternative ways to carry out research without the use of animals such as primates.

Rhesus macaques (Macaca mulatta)

Rhesus macaques (Macaca mulatta) are widely used in science due to their availability and closeness to humans anatomically and physiologically.

Researchers in the US have trailed a vaccine in these monkeys which they say has completely protected the primates against infection with simian immunodeficiency virus (SIV), a virus related to HIV that infects the animals. Studies indicate the experimental vaccine has the potential to clear the body of all traces of the virus – a significant breakthrough.

The vaccine offered protection to 13 of 24 rhesus macaques treated in the experiment and in 12 of the monkeys, the vaccine was still effective a year later.

Lead author Professor Louis J Picker, of the Vaccine and Gene Therapy Institute in Oregon, thinks it will be possible to have a vaccine ready to test in people within three years. He said: “We feel it has a possibility of keeping the virus under complete control or clearing the virus.”

Researchers say the vaccine works by priming the immune system to quickly attack the HIV virus when it first enters the body, a point at which the virus is most vulnerable.

Picker and colleagues used what they called a ‘relatively harmless’ virus  – cytomegalovirus (CMV)  – as a ‘transport system’ to take the experimental vaccine into the body. They chose it because they think most people are already infected with CMV — a virus that remains in the body for life but causes little or no symptoms for most people.

The team had the idea that a permanent virus could programme the immune system to be permanently on the alert for HIV.

But some scientists are concerned about safety and regulatory issues in giving humans CMV, because it is not totally benign. Professor Sir Andrew McMichael of Oxford University said: “CMV does cause a number of diseases. If you’re giving people something you’re not going to be able to get rid of should it cause problems, then that’s quite a difficult risk to manage.”

Dr Picker added: “On one level ninety-nine per cent of people in sub-Saharan Africa are CMV-positive and half the people in the developed world are, so we know at lot about it and it’s mostly non-pathogenic, except in vulnerable populations like pregnant women,” he said.

“We’re fully aware to make it available to humans, then the next step is to make a virus which retains or has an enhanced ability to make effector memory cells, but no longer has the capacity to infect vulnerable parts of the population. For a human vaccine, the CMV vector would be weakened sufficiently so that it does not cause illness, but will still protect against HIV.”

HIV is the fastest growing serious health problem in the UK with 83,000 people infected. There is no cure for AIDS, but a cocktail of drugs can keep the disease at bay for many years. According to the United Nations agency, UNAIDS, more than 25 million people have died since 1981 and there are just over 33 million people infected worldwide.

HIV can be spread in so many ways – through sex; sharing needles, via breast milk and blood so there is no definitive way to prevent infection. A vaccine  really is the best hope.

Robin Shattock, a professor of mucosal infection and immunity at Imperial College London, said: “Before this publication, scientists had pretty much given up on the idea of a vaccine that could control HIV replication. This puts it back on the agenda.”

The study by Picker and colleagues has been published in the journal, Nature.

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