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Testing a vaccine to slow HIV

The study is looking to recruit 200 volunteers between the ages of 18 - 45. Participants must be on antiretroviral therapy with viral loads that are well controlled at about 50 copies per millilitre of blood. The criteria distinctly classify the study as research for a therapeutic intervention against HIV. The candidate vaccine is called TAT. It is a Phase II clinical trial and will investigate the safety of the product and whether it generates an immune response or what is called immunogenicity. Participants are required to take their ARVs when on the study. Professor Maphoshane Nchabeleng, the Principal Investigator in the Medunsa study, says they are investigating what health restorative qualities the candidate vaccine has that ARVs do not possess.

“The main thing is to look at the response of their immune systems. So, we are going to continue taking blood from these participants who have been immunised looking at specific markers in the blood which will reflect the stimulation of the immune system the way we would want it to be stimulated… immune response in the form of antibodies. We are going to be looking at the stimulation of specific cells that are known to be immune response cells”.

Professor Nchabeleng went on to explain why the TAT vaccine is being considered as a possible therapeutic intervention to slow progression of disease associated with HIV infection.

“This is a protein that is produced by the virus. It’s a very important regulatory protein in the development of the disease. For other diseases we know… say measles… you and I most probably got measles when we were children and we won’t get it again because after being exposed to this disease we get immunised naturally. Our bodies can be able to then protect us against that particular disease”.

“But HIV has shown to be a very, very difficult disease. Despite the fact that you have developed antibodies, they do not protect you. They do not make you recover from the disease. Instead, your body becomes weaker and weaker and weaker. But it has been found that people whose immunity against this particular TAT protein… if that immunity can persist, they tend not to progress in their disease quicker. That is why it was then identified to look at it as a potential vaccine to say: Can we now take this and develop it into a vaccine so that we can immunise people and look at whether if they have developed immunity against it after the vaccination, will it also protect their bodies so that their disease does not progress the very same way as what was discovered in those who naturally continued to have the immunity?”, she said.

Laboratory examinations will be undertaken to make sure that participants do not have TAT antibodies for enrolment into the study. Early studies involving the TAT vaccine have been conducted in Italy and are still continuing.

“In Phase 1 trials in Italy, both preventative trials (in) sero-negative individuals and therapeutic trials in HIV-infected individuals… The vaccine was safe and immunogenic. After all the ethical approval we went to a Phase 2 study with individuals on antiretroviral treatment and we made an interim analysis last summer and it indicates the vaccine is safe and immunogenic”, according to Professor Barbara Ensoli, Director of the Italian National AIDS Centre.
In scientific terms, the study is defined as a randomised, double-blind placebo-controlled trial. That means that out of the total number of participants half will be given the actual TAT vaccine and the remainder a fake vaccine and none of the people will know; nor will the staff conducting the trial until it finishes and the data is analysed. Professor Nchabeleng warned potential participants that the vaccination, which will be administered through injection over several months over a year, will not replace their ARV treatment.

“People should not change what they have been taught because they now think they have received a vaccine. It’s a clinical trial”, Professor Nchabeleng said.

Source: Health-e News , By Khopotso Bodibe

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