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: email@example.com)
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
Phone.: +41 44 255 34 50
Media - Abteilung Kommunikation | idw - Informationsdienst Wissenschaft
A promising target for kidney fibrosis
21.04.2017 | Brigham and Women's Hospital
Stem cell transplants: activating signal paths may protect from graft-versus-host disease
20.04.2017 | Technische Universität München
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
25.04.2017 | Physics and Astronomy
25.04.2017 | Materials Sciences
25.04.2017 | Life Sciences