Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Persistent adaptability


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:

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

Prof. Dr. med. Huldrych Günthard
Division of Infectious Diseases and Hospital Epidemiology
Universitätsspital Zürich
Phone.: +41 44 255 34 50

Weitere Informationen:

Media - Abteilung Kommunikation | idw - Informationsdienst Wissenschaft

More articles from Health and Medicine:

nachricht Inflammation Triggers Unsustainable Immune Response to Chronic Viral Infection
24.10.2016 | Universität Basel

nachricht Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg

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: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>