Google – AFP, 1 November 2013
 |
A man walks
past an AIDS campaign board in Seoul, Korea, on December 1,
2005, as part of
World AIDS Day (AFP/File, Kim Jae-Hwan)
|
Washington
— US scientists seeking to unravel the mysteries of HIV have made an important
breakthrough after capturing the clearest image yet of a protein which allows
the deadly virus to attack human immune cells, new research showed Tuesday.
Scientists
at The Scripps Research Institute (TSRI) and Weill Cornell Medical College have
managed to obtain a detailed view of the atomic structure of the protein which
envelops HIV, the virus which causes AIDS.
The
development could potentially pave the way for a vaccine, according to the
findings published in the US journal Science.
"In
order to develop a vaccine, you have to understand what bits on that very
important trimeric protein can be recognizes by broadly neutralizing
antibodies," said Scripps Institute cell biologist Bridget Carragher.
"And
in order to understand that, you need to understand what the structure of the
thing looks like.
"Then
once you do, you can start designing a vaccine that will mimic that thing and
elicit an antibody response and get the human being to fight the real virus
when it comes along."
Although
sophisticated antiviral drugs have been used to manage HIV infections in many
developed countries, a vaccine against infection has proved elusive.
The failure
to find a vaccine is often attributed to the complex nature of HIV's envelope
protein, known as Env.
The
delicate structure of Env has hampered efforts to obtain the protein in a form
that allows for the atomic-resolution imaging necessary to fully understand it.
"It
tends to fall apart, for example, even when it's on the surface of the virus,
so to study it we have to engineer it to be more stable," said TSRI
biologist Andrew Ward.
However the
researchers were able to engineer a version of the Env trimer, or
three-component structure, that has the stability required for
atomic-resolution imaging.
The scientists
were then able to study the Env trimer using cutting-edge imaging and electron
microscopy.
The use of
X-ray crystallography allowed researchers to examine the Env trimer in more
detail than previous attempts.
The data
also shed light on the process by which Env assembles and later shifts shape
during infection, and also allowed researchers to make comparisons with protein
envelopes from other deadly viruses such as flu and Ebola.
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