Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Persistent adaptability

28.01.2015

Drug-resistant HIV viruses can spread rapidly. This is the conclusion of a study conducted as part of the SWISS HIV Cohort Study, which is supported by the SNSF. Only the continuous introduction of new drugs can stop the virus from getting the upper hand.

The adaptability of pathogens is a great challenge to modern medicine, particularly the growing bacterial resistance to antibiotics. But other pathogens also possess the ability to adapt and render drugs powerless. A new study, conducted as part of the SWISS HIV Cohort Study, now shows how drug resistance can spread if it is not hindered by the continuous introduction of new drugs.

"Modern therapies can practically stop HIV viruses from replicating in the bodies of patients," says Huldrych Günthard, President of the HIV Cohort Study and Professor of Infectious Diseases at the University Hospital Zurich.

"On the basis of this, fewer drug-resistant viruses should occur and be transmitted than a few years ago." However, studies have shown that this is not necessarily the case: the number of drug-resistant viruses that have been transmitted from one patient to another has remained stable.

New drugs offer respite

To explain this seeming paradox, Günthard and his colleagues have examined the viral resistances that have occurred in the HIV Cohort between 1998 and 2012. According to their recently published study (*), the proportion of patients with transmitted resistant viruses comes to about 10% for the entire period, but the transmission rate fluctuated considerably.

Two opposing developments have contributed to these fluctuations, explains Günthard: when a new class of drugs entered the market, the transmission rate of resistant viruses dropped significantly for a period. This happened in 2000 after approval of the so-called "boosted protease inhibitors" and in 2009 when "integrase inhibitors" started to be used. But in both cases, the rate of transmission gradually climbed back up after the initial drop. "This shows how important a constant supply of new drugs is," explains Günthard.

Varying patterns of Transmission

The researchers were also able to show how different the transmission patterns of individual types of resistant viruses can be. Worldwide, there are over 100 significant known mutations which lead to a resistance of the HI virus to one or more drugs. One frequently occurring mutation named M184V is transmitted mainly by HIV patients who receive drug therapy. In the case of two different but also frequently occurring mutations (L90M and K103N), patients who do not receive drug treatment seem to be the preferred host.

"This is probably the result of differing fitness costs of the mutations," says Günthard. M184V mutations quickly revert to their "un-mutated" state in untreated patients because the mutation limits viral replication; as a result, M184V viruses multiply above all in treated patients, who can can transmit them to other persons. On the other hand, L90M and K103N can also multiply in the absence of drugs, which means that untreated patients can propagate these two types of resistance. According to Günthard, these results exemplify that the spread of viral resistances is even more complex than previously assumed.

(*) Assessing the paradox between transmitted and acquired HIV-1 drug resistance in the Swiss HIV Cohort Study from 1998 to 2012,
Wan-Lin Yang, Roger Kouyos, Alexandra U Scherrer, Jürg Böni, Cyril Shah, Sabine Yerly, Thomas Klimkait, Vincent Aubert, Hansjakob Furrer, Manuel Battegay, Matthias Cavassini, Enos Bernasconi, Pietro Vernazza, Leonhard Held, Bruno Ledergerber, Huldych F. Günthard, and the Swiss HIV Cohort Study (SHCS), Journal of Infectious Diseases. 2014
(Journalists can obtain a PDF file from the SNSF by writing to: com@snf.ch)

Related literature

The interplay between transmitted and acquired HIV-1 drug resistance: the reasons for a disconnect, Andrea De Luca and Maurizio Zazzi, Journal of Infectious Diseases, Advance Access, published January 9, 2015
(Editorial)

Contact
Prof. Dr. med. Huldrych Günthard
Division of Infectious Diseases and Hospital Epidemiology
Universitätsspital Zürich
Phone.: +41 44 255 34 50
E-mail: huldrych.guenthard@usz.ch

Weitere Informationen:

http://www.snf.ch/en/researchinFocus/newsroom/Pages/news-150128-press-release-pe...

Media - Abteilung Kommunikation | idw - Informationsdienst Wissenschaft

More articles from Health and Medicine:

nachricht NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures
17.11.2017 | National Institute of Standards and Technology (NIST)

nachricht High speed video recording precisely measures blood cell velocity
15.11.2017 | ITMO University

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>