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!
Researchers reach milestone in use of nanoparticles to kill cancer with heat
27.06.2019 | Oregon State University
New combination therapy established as safe and effective for prostate cancer
26.06.2019 | Society of Nuclear Medicine and Molecular Imaging
For the first time ever, experimental physicists have been able to influence the magnetic moment of materials in sync with their electronic properties. The coupled optical and magnetic excitation within one femtosecond corresponds to an acceleration by a factor of 200 and is the fastest magnetic phenomenon that has ever been observed.
Electronic properties of materials can be directly influenced via light absorption in under a femtosecond (10-15 seconds), which is regarded as the limit of...
From June 25th to 27th 2019, the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau (Germany) will be presenting a new solution for acoustic quality inspection allowing contact-free, non-destructive testing of manufactured parts and components. The method which has reached Technology Readiness Level 6 already, is currently being successfully tested in practical use together with a number of industrial partners.
Reducing machine downtime, manufacturing defects, and excessive scrap
The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.
Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...
The well-known representation of chemical elements is just one example of how objects can be arranged and classified
The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...
Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.
Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...
24.06.2019 | Event News
29.04.2019 | Event News
17.04.2019 | Event News
27.06.2019 | Health and Medicine
27.06.2019 | Life Sciences
27.06.2019 | Life Sciences