Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Step in breakdown of HIV proteins essential to recognition, destruction of infected cells

10.05.2011
Variations in peptide stability may alter targeting of infected cells by CD8 T cells

A key step in the processing of HIV within cells appears to affect how effectively the immune system's killer T cells can recognize and destroy infected cells. Researchers at the Ragon Institute of MGH, MIT and Harvard have found that – as HIV proteins are broken down within cells, a process that should lead to labeling infected cell for destruction by CD8 T cells – there is a great variability in the stability of resulting protein segments, variations that could significantly change how well cells are recognized by the immune system. Their report appears in the June Journal of Clinical Investigation.

"We have identified a novel mechanism by which HIV escapes recognition by virus-specific cytotoxic T cells, says Sylvie Le Gall, PhD, of the Ragon Institute, the paper's senior author. "This discovery may help us better understand the immune-system failure that characterizes HIV infection and provide information critical to the successful development of immune-system-based therapies."

CD8 T cells that have been programmed to target and destroy HIV-infected cells recognize those cells through tiny bits of viral protein, called peptides, displayed on the cell surface. Details of how HIV proteins are broken down into peptides and loaded onto the specialized molecules, called MHC Class I, that carry them to the cell surface are not well understood. Also unknown is whether particular HIV peptides are more effective than others in flagging cells for destruction.

Le Gall and her team first discovered that HIV peptides reduced to a length of 8 to 11 amino acids within infected cells varied greatly in their stability, with some breaking down further within seconds and others remaining unchanged for nearly an hour. Collaborators David Heckerman, MD, PhD, and Carl Kadie from Microsoft Research analyzed the biochemical features of 166 HIV peptides and identified particular structural patterns associated with either stability or instability. The researchers then showed that substituting a stability-associated structural motif for an instability motif significantly increased peptide stability, and vice-versa.

The stability of a peptide within the cell can significantly affect how much peptide is available to be loaded onto MHC Class I molecules and displayed on the cell surface. The authors found that several known HIV mutations significantly reduced peptide stability – one common mutation virtually abolished the cell-killing action of CD8 T cells. The Microsoft team members have developed a model to predict the probable stability of specific HIV peptides, but more research is needed to determine how variations in stability affect the presentation of the peptide segments called epitopes to CD8 cells and whether changes in peptide stability lead to a more efficient immune response.

"Efforts to develop T-cell-based vaccines need to focus on producing epitopes that elicit the most protective response," says Le Gall, an assistant professor of Medicine at Harvard Medical School. "Modulating peptide stability offers a unique way of regulating epitope presentation in favor of producing the most effective defence against HIV."

Additional co-authors of the Journal of Clinical Investigation report are lead author Estibaliz Lazaro, ,MD; Pamela Stamegna; Shao Chong Zhang, PhD; Pauline Gourdain, PhD; Nicole Y. Lai; Mei Zhang and Sergio A. Martinez, all of the Ragon Institute. The study was supported by grants from the Bill and Melinda Gates Foundation and the National Institute of Allergy and Infectious Disease.

The Ragon Institute of MGH, MIT and Harvard was established in 2009 with a gift from the Philip T. and Susan M. Ragon Foundation, creating a collaborative scientific mission among these institutions to harness the immune system to combat and cure human diseases. The primary initial focus of the institute is to contribute to the development of an effective AIDS vaccine. Administratively based at Massachusetts General Hospital, the Ragon Institute draws scientists and engineers from diverse backgrounds and areas of expertise across the Harvard and MIT communities and throughout the world, in order to apply the full arsenal of scientific knowledge to understanding mechanisms of immune control and immune failure and to apply these advances to directly benefit patients.

Sarah Dionne | EurekAlert!
Further information:
http://www.massgeneral.org

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>