Washington, Oct 29 (PTI) Scientists have developed anovel vaccine candidate that may prevent HIV infection bystimulating an immune response against sugars that form aprotective shield around the virus.
"An obstacle to creating an effective HIV vaccine is thedifficulty of getting the immune system to generate antibodiesagainst the sugar shield of multiple HIV strains," said Lai-XiWang, a professor at University of Maryland in the US.
"Our method addresses this problem by designing a vaccinecomponent that mimics a protein-sugar part of this shield,"said Wang.
Researchers designed a vaccine candidate using an HIVprotein fragment linked to a sugar group. When injected intorabbits, the vaccine candidate stimulated antibody responsesagainst the sugar shield in four different HIV strains.
The protein fragment of the vaccine candidate comes fromgp120, a protein that covers HIV like a protective envelope.
A sugar shield covers the gp120 envelope, bolsteringHIV's defenses. The rare HIV-infected individuals who can keepthe virus at bay without medication typically have antibodiesthat attack gp120.
Researchers have tried to create an HIV vaccine targetinggp120, but had little success as the sugar shield on HIVresembles sugars found in the human body and therefore doesnot stimulate a strong immune response.
More than 60 strains of HIV exist and the virus mutatesfrequently. As a result, antibodies against gp120 from one HIVstrain will not protect against other strains.
To overcome these challenges, researchers focused on asmall fragment of gp120 protein that is common among HIVstrains.
They used a synthetic chemistry to combine the gp120fragment with a sugar molecule, also shared among HIV strains,to mimic the sugar shield on the HIV envelope.
Researchers then injected the protein-sugar vaccinecandidate into rabbits and found that the rabbits' immunesystems produced antibodies that physically bound to gp120found in four dominant strains of HIV in circulation today.
Injecting rabbits with a vaccine candidate that containedthe protein fragment without the sugar group resulted inantibodies that primarily bound to gp120 from only one HIVstrain.
"This result was significant because producing antibodiesthat directly target the defensive sugar shield is animportant step in developing immunity against the target andtherefore the first step in developing a truly effectivevaccine," Wang said.
Although the rabbits' antibodies bound to gp120, they didnot prevent live HIV from infecting cells. This result did notsurprise Wang, who noted that it usually takes humans up totwo years to build immunity against HIV and the animal studyonly lasted two months.
"But the ability of the vaccine candidate to raisesubstantial antibodies against the sugar shield in only twomonths is encouraging," Wang said.
"Other studies took up to four years to achieve similarresults. This means that our molecule is a relatively stronginducer of the immune response," he said. PTI MHNMHN.
This is unedited, unformatted feed from the Press Trust of India wire.