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Potent antibodies against HIV identified

Thursday, Apr 7, 2016,13:04 IST By Metrovaartha A A A

Washington | Scientists have isolated antibodies with a loop-like structure that binds tightly to HIV and disables it – even in people who have never been infected by the deadly virus. It has been known that the immune system can produce antibodies capable of neutralising HIV, and stopping the AIDS-causing virus dead in its tracks.

The problem is, less than a third of people produce broadly neutralising antibodies in response to HIV infection and it takes a year or more before production gets into full swing. Efforts to develop a vaccine that can jumpstart an effective immune response to HIV so far have been unsuccessful.

Now, researchers at Vanderbilt University in US have isolated antibodies with a loop-like structure that binds tightly to HIV and disables it – even in people who have never been infected by the virus.

Using computer modelling, they re-engineered and optimised the antibodies’ neutralising capacity. The findings suggest that it may be possible to rapidly induce broadly neutralising antibodies against HIV in people who have not been exposed previously to HIV by using a structure-based vaccine design approach.

The study led by Jens Meiler, associate professor of Chemistry and Pharmacology, and James Crowe Jr, Professor and director of the Vanderbilt Vaccine Centre focused on the antibodies’ loop-like structure that binds tightly to HIV. It is made up of 28 amino acids that are strung together in different combinations.

They used a computer programme called Rosetta to identify which amino acid sequences bound most tightly to HIV. They then used the same programme in silico (via computer modelling) to optimise the sequences in a way that simulated a vaccination event.

Finally, they fused these sequences onto a type of monoclonal antibody, called PG9, which is known to be a broad neutraliser of the virus. Laboratory tests confirmed that the re-engineered antibodies effectively neutralised HIV.

Crowe said that a vaccine that presents the HIV sequence recognised by such antibodies would increase the chance that a large proportion of the vaccinated population could respond to the virus with a broad and potent antibody response.