Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Viral ’fitness’ explains different resistance patterns to aids drugs

11.01.2006


Some HIV medications lead to the development of drug-resistant HIV when patients take as few as two percent of their medications. For other medications, resistance occurs only when patients take most of their pills. These differences appear to be explained by the different levels of viral "fitness" of the drug-resistant HIV, say AIDS researchers in a new study.



The research, led by David Bangsberg, MD, MPH, an AIDS specialist at the University of California, San Francisco, is reported in the January 9 issue of the journal AIDS.

Viral "fitness" refers to the inherent ability of a virus to replicate and cause disease. Incomplete pill-taking by patients causes HIV to mutate and become resistant to the effects of the medications, while the medications that were consumed, in turn, cause the newly resistant virus to become less fit.


The type of medication also factors in. Differences in viral fitness of mutated resistant virus occur between different classes of antiretroviral drugs, said Bangsberg, who is an associate professor of medicine at UCSF and director of the UCSF Epidemiology and Prevention Interventions Center at San Francisco General Hospital Medical Center.

When patients succeed in completely suppressing HIV, which requires that patients take all or almost all of their medications as directed, resistant strains either do not occur or are suppressed, he added.

Explaining the study results, Bangsberg said, "A non-nucleoside reverse transcriptase inhibitor (NNRTI), for example, can be taken one time by a pregnant woman to prevent mother-to-child transmission, and NNRTI-resistant HIV virus can develop. Yet patients taking unboosted protease inhibitors (PI) do not experience the peak risk of PI-resistant HIV developing unless they are taking most of their PIs but fall just short of full viral suppression."

The researchers found that NNRTI-resistant virus has an advantage over sensitive virus even at very low levels of adherence. This happens because only a single mutation is required to create high-level NNRTI resistance and these mutations have little impact on the virus’s ability to replicate. PI-resistant virus, in contrast, requires multiple mutations, each of which significantly weakens the ability of the virus to replicate. These PI-resistant viruses only emerge, therefore, when challenged with high concentrations of drug.

Overall, study findings showed that NNRTI resistance was found less often than PI resistance among patients who took the pills as directed.

"We believe that when new drug classes are developed, more attention should be given in defining how virologic fitness determines how different patterns of taking medications may lead to resistance" said Steven Deeks, MD, associate professor of medicine at UCSF’s Positive Health Program at SFGHMC and senior author on the study.

Both NNRTIs and non-boosted protease inhibitors are potent antiretroviral drugs (ARVs) with demonstrated effectiveness in suppressing the HIV virus when taken in combination with other ARVs at high levels of pill-taking as directed. The standard combination therapy usually includes either one NNRTI or protease inhibitor (non-boosted or boosted with a small amount of another potent PI) and two different antiretrovirals from the nucleoside reverse transcriptase inhibitor class.

Jeff Sheehy | EurekAlert!
Further information:
http://www.ari.ucsf.edu

More articles from Health and Medicine:

nachricht Organ-on-a-chip mimics heart's biomechanical properties
23.02.2017 | Vanderbilt University

nachricht Researchers identify cause of hereditary skeletal muscle disorder
22.02.2017 | Klinikum der Universität München

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>