Chink in AIDS virus raises vaccine hope

NEW DELHI: It's a chink in the armour. And it could just be the weak link in the human immunodeficiency virus that researchers hunting for an elusive breakthrough to develop a preventive vaccine for HIV have been hunting for in vain.

In a significant breakthrough, researchers at the National Institute of Allergy and Infectious Diseases (NIAID) in US, have captured a 3-D X-ray image of a key area of an HIV surface protein, which, unlike the rest of the constantly mutating virus, remains stable.

This stable section is vulnerable to attack from a specific antibody, known as b12, that is capable of destroying the virus.

This revelation - of HIV's long-sought "site of vulnerability"- will greatly help in the design of the elusive AIDS-vaccine.

Such a vaccine is expected to prevent initial infection. This is reason for some celebration as researchers point out that HIV is so deadly, precisely because the virus is coated with slippery surface proteins that are constantly changing as the infection spreads.

So antibodies - immune system proteins - that destroy viruses and bacteria entering our body are unable to recognise HIV and penetrate it.

This is what makes the virus evade our immune system so efficiently. With this finding, scientists now know how to get past the formidable defence of the AIDS virus and where exactly to hit it.

What they have to find now is a way to get the human body to produce lots of b12 antibodies before the onset of infection.

Lead researcher Peter Kwong said, "The more we learn about HIV, the more we realise just how many levels of defence the virus has against attacks by the immune system. Not only does HIV mutate rapidly and continuously - defeating attempts by the immune system to identify and destroy it - the virus is also swathed by sugary molecules. This impenetrable cloak prevents antibodies from slipping in and blocking proteins the virus uses to latch onto a cell and infect it."

Speaking to TOI, Dr Suniti Solomon, who first discovered HIV in India, said the virus's constant mutation has made vaccine research against HIV very difficult.

Even before scientists are ready with a vaccine, the virus mutates and changes, making the vaccine useless.