World AIDS Day 2014
55 years ago, the first known case of HIV in a human occurred in a man who died in the Congo. Since then a lot has been done to turn this deadly disease into one we can now live almost normally with - a diagnosis of HIV infection is no longer a death sentence.
With international AIDS day, it’s an opportunity to look at the important role of animals in the discovery of HIV, finding a functional treatment for HIV and now researching for a vaccine against HIV.
Our website already provides some of that story, here we tell a little more
HIV is a retrovirus, a type of lentivirus which can cause slow progressive disease in their host. An equivalent AIDS virus can be found in horses, cattle, sheep, cats and monkeys.
“Mice and the Rhesus macaque were the most used animal models to understand HIV biology and to develop treatment” explains Dr Monsef Benkirane, director of the human genetic CNRS institute in Montpellier and specialist in HIV persistence. “Their contribution to our understanding of HIV/SIV biology was and still essential.”
Following the discovery of HIV, the related lentivirus in monkeys called SIV was found, leading to the use of monkeys to study the virus and develop treatments for HIV and AIDS. For example, understanding why SIV is not pathogenic in its natural host will certainly contribute to the development of effective therapy and vaccine.
By 1996 combination therapy had increased life expectancy for those with HIV by decades, but this therapy is unable to cure AIDS.
“One of the priorities in the field is to optimise HIV treatments. For this purpose, we need to assess whether the therapeutic compounds go where they are needed in the body of the patients. We also need to know how stable they are in these compartments. For this, the animal models are essential” adds Benkirane. “We are still trying to locate the cells that allow the virus to bounce back after treatment and a way to target them.”
Monkeys are essential in this research. The ultimate goal is still an effective vaccine. “There is no protective vaccine against HIV today and it is a priority to find one. We know that this is not going to be easy since we will have to find way to do better than our immune system. To do so you have to try to do better than the immune system itself.”, assures Dr Benkirane. “If one day we find a vaccine, it won’t be a classic vaccine like we know them today. It will be profoundly new.”
Classic antibody vaccines haven’t proven to be efficient enough because of the viral diversity of HIV and its capacity to adapt fast. Vaccines targeting the cell of the immune system, and activating T lymphocytes have just made the virus thrive even more. Gene therapy is also being tried out, but it still comes with many side effects. Because HIV infects the immune system, evades it and changes so rapidly, finding a way to vaccinate against it has been particularly challenging.
Important and promising advances have been recently achieved by scientists working at the development of powerful antibodies able to neutralize HIV. Indeed, scientists found that 20% of AIDS patients develop special types of neutralising antibodies with a large inhibition spectrum, meaning they can act against all the diverse HIV subtypes.
“The discovery of broadly neutralising antibodies brings a hope for HIV cure. Indeed, proof of concept of their efficacy using animal models has been recently reported. Indeed, these antibodies are able to decrease the viral load in chronically infected animal even better than the antiretroviral drugs in use today. These antibodies can be used in high risk individuals as mean of preventing viral transmission. Based on results obtained using animal models, clinical trials using this antibodies are ongoing.”, explains Benkirane.
“The use of animals in research is still necessary and unavoidable today to make progress regarding HIV. However, everything is done with precise regulations and rules. The European laws are very demanding and strict. Researchers must show that the use of animals is essential for obtaining the agreement of ethic committees. And only then, they can proceed to experimentation. Finding a cure and a vaccine to stop the HIV pandemic requires the use of animal models.”
Currently mice and monkeys are being used to find a ‘vaccine’ that can stimulate the production of neutralising antibodies. It is only when this work is completed that we can contemplate the use of this new treatment in people.
Dr M. Monsef BENKIRANE, is Director of Research at CNRS at l’Institut de génétique humaine (CNRS), at Montpellier.
Download our AIDS timeline infographic here.