NEW DELHI: Could an antibody from the blood of an Indian HIV patient help create the elusive HIV vaccine? (Antibody is an infection-fighting protein produced by our immune system when it detects harmful substances).
The hunt has begun to identify 100 volunteers belonging to a rare group of HIV infected patients who stay healthy for years without requiring life-saving antiretroviral treatment (ART). These antibodies in their blood are the ones that bars HIV from entering their blood cells and replicating, thereby progressing to AIDS, the Times of India reports.
Scientists say these antibodies would ultimately reveal the Achilles heel of the virus and help create the elusive vaccine. This is part of International Aids Vaccine Initiative’s (IAVI) programme called Protocol G, a global hunt for such antibodies launched in 2006.
So far, blood samples of 1,800 such HIV patients have been screened across 12 countries and 19 broadly neutralizing antibody (bNAbs) have been identified. A bNAb is an antibody capable of stopping a variety of HIV subtypes from infecting their target cells.
“Only a minority of people who are infected with HIV produce bNAbs. Although HIV is a wildly mutable virus, certain parts of it are relatively resistant to change. These parts are essential to the virus’s ability to infect, and they are the elements of HIV that bNAbs target,” experts said.
Just a few weeks ago, department of biotechnology (DBT) cleared the proposal to roll out Protocol G in the country. It is being implemented by IAVI and YRG Care from Chennai – the same organization that isolated the first HIV case in India in 1986.
The blood samples collected from the 100 volunteers will be tested at Translational Health Sciences and Technology Institute (THSTI), which is being built in Gurgaon.
IAVI’s India chief Dr Rajat Goyal told TOI that “This is a landmark project for India. We are presently identifying volunteers, who are at least 18 years, infected with HIV at least three years ago but has not received ART. By April, samples will be picked up and tested against a standard panel of HIV isolates by the end of 2012. We will then know whether there is a population of interest from whom these bNAb can be identified and characterized.”
Careful study of bNAbs is expected to reveal vulnerabilities of the different types of HIV. Most importantly, scientists expect that they can use information about how bNAbs bind to HIV to construct immunogens – the active ingredients of vaccines – that elicit similar antibodies. The more such antibodies researchers have in hand, the more clues they can get about how best to target HIV with a vaccine.
The project has tested HIV patients in Thailand, the UK, the US, Nigeria, South Africa, Rwanda, Uganda, Kenya, Australia and Zambia to identify bNAbs.
HIV infects 7,100 people daily. The quest to develop an AIDS vaccine has consumed scientists for 25 years since the discovery of HIV. Scientists say HIV is the most mutable virus ever encountered. A number of different subtypes of the virus, known as clades, circulate in different regions of the world. Within those clades there is considerable variability, and, beyond that, the virus mutates furiously within the people it has infected.
Second, because no one is known to have cleared an HIV infection, scientists do not know which elements of the immune response must be engaged to control the virus – and thus are uncertain how to replicate such responses.
The immune system has a very narrow window of opportunity in which to neutralize HIV before the virus establishes a lifelong infection.