The extreme diversity of human immunodeficiency virus (HIV) strains is a major obstacle to anti-AIDS vaccine elaboration or the development of new treatments against the disease. IRD scientists, working jointly with other institutes (1), used statistical methods to determine the adaptive molecular mechanisms the virus deploys to avoid neutralization by the host immune defences. This adaptive molecular evolutionary strategy, based on genetic variability, proved to be a feature common to the different HIV subtypes. The virus apparently uses the great variety of its envelope-protein receptor binding sites, which have the role of fixing large complex carbohydrate molecules in the form of glycans, to provide protection against the host’s antibodies. These sugars are large structures that apparently block the way of human antibodies that would otherwise fix on to the virus, without hindering these envelope proteins in their function of attaching the virus to the host cell. These results open the way to potential ways of tackling AIDS.
In humans, the AIDS virus HIV manifests extreme genetic variability. It is particularly virulent, probably because its introduction into populations is recent (2). It has a potential for rapid evolution, at both population and individual scales, owing to a mutation rate among the highest in the living world, and to its recombination capacity. This high evolutionary potential is one of the major obstacles hindering the development of an effective vaccine. Starting from the principle that this mutation-based evolution of the virus is a response to selective pressures exerted by the host immune response (thought to be the dominant evolutionary force) , IRD researchers and their project partners (1) attempted to determine, at the molecular scale, the adaptive mechanisms at work and their comparative occurrence between the different HIV groups and subtypes. They used powerful statistical techniques (the codon-based maximum likelihood method) to investigate and compare the evolution of 3 major genes of the HIV genome, gag, pol and env. They did this for several HIV subtypes. They were able to confirm that the virus followed a dynamic adaptation strategy, based on the deployment of a shield of complex carbohydrates (glycans) to block antibody binding and thus provide protection against the host immune response.
Among the mutations randomly affecting the genome as a whole, those which influence the genes essential for viral survival and multiplication appear to be systematically selected against (negative selection). The gag gene, which codes for the proteins of the capsid (containing the genome and the viral proteins) and the pol gene, which allows synthesis of enzymes essential for virus replication, thus appear highly conserved and stable from one subtype to another.
Bénédicte Robert | EurekAlert!
The genes are not to blame
20.07.2018 | Technische Universität München
Targeting headaches and tumors with nano-submarines
20.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences