Scientists hopeful of ‘full-length single chain’ AIDS vaccine


NewsGram Staff Writer

Robert Gallo, the scientist who first proved in 1984 that HIV triggered the disease AIDS, is again all set to begin the trial of its vaccine in the US. The vaccine which has been developed over the past 15 years by Gallo is a little different and is expected to bear fruitful results.

The initial phase, involving 60 volunteers, will test the safety and immune responses of the vaccine. This study will reveal whether the vaccine is more effective than the other 100+ AIDS vaccines that have been tested over the last three decades. Extensive testing on monkeys have yielded positive results.

Despite the presence of potential vaccines, the challenge with AIDS is that HIV directly infects white blood cells (RBC) called T-cells, so it literally turns our immune system against us. So, once the virus enters a T-cell, it’s invisible to the immune system.

The sole possibility to combat the threat is to pump in antibodies against the HIV surface proteins. However, doing so is equally difficult owing to the fact that the retrovirus can regularly change its viral envelope to hide particular surface proteins.

But Gallo and his team at the Institute of Human Virology in USA believe that they may have now found a moment when the HIV surface protein, known as gp120, is vulnerable to detection – the moment the virus binds with our bodies’ T-cells.

When HIV infects a patient, it first links to the CD4 receptor on the white blood cell. It then transitions, exposing hidden parts of its viral envelope, which allow it to bind to a second receptor called CCR5. Once HIV is attached to both these T-cell receptors, it can successfully infect the immune cell. at this stage, it is impossible to stop its juggernaut.

Gallo’s “full-length single chain” vaccine contains the HIV surface protein gp120, engineered to link to a few portions of the CD4 receptor. The motive is to fuel antibodies against gp120 when it is already attached to CD4 and is in a vulnerable transitional state. The aim of the whole process is effectively stopping it from attaching to the second CCR5 attachment.

Gallo himself admitted to Jon Cohen over at Science that full-length single chain vaccine is a “terrible name”.

The trial is being run in collaboration with Profectus BioSciences, a biotech spin-off from the Institute of Human Virology, and Gallo explained that extreme thorough testing on monkey and getting the fund to develop a human-grade vaccine have resulted in a delay to get to this point.

“Was anything a lack of courage?” he asked Science. “Sure. We wanted more and more answers before going into people.”

Let’s hope that caution pays off, and we may finally have a viable contender for an AIDS vaccine on our hands.

(With inputs from