peripheries

Luc Montagnier: an HIV vaccine as additional therapy rather than prophylaxis

October 21st, 2008 | by Admin |

In an opinion piece published in The Wall Street Journal, Prof Luc Montagnier co-discoverer with Francoise Barré-Sinoussi of the HIV virus that causes AIDS, proposed “using vaccination against HIV antigens not for prophylaxis, but as additional therapy following a short antiviral treatment”

Following a wave of failures in the development of an HIV vaccine, starting with AIDSVax in 2003 and ending with the STEP trial in 2007, Prof Montagnier reiterated a proposal he made more than 10 years ago but that would not have looked out of place at the last AIDS vaccine conference in Cape Town.

Twenty five years after its isolation the HIV virus still escapes the immune system for several reasons. The first is that the virus attacks and destroys the cells that are specialised in getting our body rid of virus and other infectious agents and protect us against infections. The second is that like the flu virus, the HIV virus can mutate very rapidly so that it is not recognised any more by our immune system. The third is that the virus can hide within our cells and stay dormant for years.

Several conventional strategies based on previous experience in vaccine design have been tried but all have failed to provide full protection and some have potentially increased the risks of HIV infection, like in the STEP trial.

Interestingly in the STEP trial it was noted that individuals in the vaccine group that were infected had a pre-existing immunity against the viral vector used to carry part of the HIV virus and even more interesting were uncircumcised men.

As the STEP trial was stop for failing, the circumcision trial in Africa was stopped for being successful (all participants were offered circumcision when it became clear that it has a protective effect for men).

It is in this context that Montagnier’s proposal is making sense: if a vaccine can not fully protect against HIV infection, it may be possible to use it as an additional therapy along anti-retroviral treatment. The vaccine could be used in HIV negative people hoping it will reduce at least partially the amount of virus in the body following nfection. Another possibility would be to first treat infected people to restore their immune system, then to apply the vaccine and monitor for a rebound in viral load, that would require resuming treatment.

In an overview of six decades of vaccine development published in 1998, Maurice Hilleman, then Director of the Merck institute for Therapeutic Research and who has developed more vaccines than anybody else, recalled that it can take a very long time to develop a vaccine. Today some diseases such as Malaria and TB which affect millions worldwide still don’t have an efficient vaccine.

Developing a vaccine as a fully efficient prevention tool or as a complement to anti-retroviral therapy remains essential. In Montagnier’s words, “In developing countries, many infected patients refuse to be tested and are not treated because of the stigma attached to AIDS. The availability of a treatment able to eradicate the infection will change their attitudes. The epidemic will thus gradually decrease, perhaps helped by a preventive vaccine derived from a successful therapeutic vaccine.”