Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Clues To Future Evolution Of HIV Come From African Green Monkeys

17.07.2007
Monkey viruses related to HIV may have swept across Africa more recently than previously thought, according to new research from The University of Arizona in Tucson.

A new family tree for African green monkeys shows that an HIV-like virus, simian immunodeficiency virus, or SIV, first infected those monkeys after the lineage split into four species. The new research reveals the split happened about 3 million years ago.

Previously, scientists thought SIV infected an ancestor of green monkeys before the lineage split, much longer ago.

"Studying SIV helps us learn more about HIV," said the paper's first author Joel Wertheim, a doctoral candidate in the UA department of ecology and evolutionary biology. "This finding sheds light on the future direction of HIV evolution."

... more about:
»Chlorocebus »HIV »Monkey »SIV »SIVagm »Worobey »grivet »infected »vervet

All SIVs and HIVs have a common ancestor, added senior author Michael Worobey, a UA assistant professor of ecology and evolutionary biology.

The new work suggests African green monkeys' SIVs, or SIVagm, may have lost their virulence more recently than the millions of years previously thought. Green monkeys almost never get sick from SIVagm. If SIVagm was once a monkey killer, the change in its virulence may shed light on the future course and timing of the evolution of HIV.

The new research also challenges the idea that one ancient SIV was transmitted vertically, down through time, and evolved into many SIVs as its original host diverged into many different species.

Wertheim and Worobey suggest various SIVs arose because SIVs were transmitted horizontally, between primate species, and evolved into a new host-specific form only after transmission.

HIV arose from chimpanzee SIV that was transmitted to humans, probably when people had contact with chimpanzee blood from hunting and butchering the animals, Worobey said.

The team's research article, "A Challenge to the Ancient Origin of SIVagm Based on African Green Monkey Mitochondrial Genomes," is in the July issue of PLoS Pathogens and can be found at http://pathogens.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.ppat.0030095. The National Science Foundation and National Institutes of Health funded the research.

Previous research had sketched out the family trees, or phylogenies, of the four species of African green monkeys and their accompanying SIVagm, but Wertheim wanted to know more.

"I wasn't convinced by the evidence out there that these monkeys were infected before they speciated," Wertheim said. "So I set out to perform a rigorous test of that hypothesis."

He extensively sequenced the mitochondrial DNA genes of the four species of African green monkeys. Mitochondrial DNA is passed from mother to child.

The four green monkeys he studied are the sabaeus monkey, Chlorocebus sabaeus, which lives in western Africa; the tantalus monkey, Chlorocebus tantalus, which is found in central Africa; the vervet monkey, Chlorocebus pygerythrus, which lives in eastern and southern Africa; and the grivet monkey, Chlorocebus aethiops, which lives in northeast Africa.

The scientists used the genetic sequences to sort out the ancestral relationships among the different species of monkeys. Other researchers had already constructed phylogenies for the four different SIVagm that showed their relationships.

"We put together, for the first time, a really solid phylogeny for African green monkeys, which we didn't have before," Worobey said.

If the monkeys' ancestor had been infected with an ancient SIV, the SIV family tree should match that of the four monkey species.

The trees didn't match.
"The monkey tree was significantly different from the virus tree," Wertheim said.

The researchers then looked at the geographic distribution of the four African green monkey species. The relative ages and information on which pairs of SIVagm were most closely related revealed the probable transmission route of SIV.

The researchers hypothesize that the infection started in the westernmost species, sabaeus monkeys, moved east into neighboring tantalus monkeys, and then took one of two paths: southeast into vervets and then north into grivets or northeast into grivets and then south into vervets.

Wertheim said, "I was surprised that the geography could explain the virus phylogenetic tree, how well it fit. You just look and -- there it is!"

The UA researchers suggest that in the border zones where two African green monkey species' ranges come in contact, transmission probably happened during interspecies sexual encounters or fights. Wertheim pointed out that hybrid monkeys have been seen in the wild in the border zones.

Worobey said, "Some of the trends we see give new evidence on how quickly or slowly these changes take place."

Citing some laboratory research that suggests HIVs from the late 1980s are more virulent than HIVs from the 2000s, Worobey added, "For HIV, the really cool thing is that these changes can take place on a more rapid timeline that previously thought."

Wertheim adds, "Understanding how emerging infectious diseases evolve in their natural host organism helps us understand the disease's possible trajectory."

The team's next steps are figuring out exactly when SIV infected African green monkeys and studying SIVs in other species of monkeys.

Joel Wertheim | University of Arizona
Further information:
http://www.arizona.edu
http://pathogens.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.ppat.0030095

Further reports about: Chlorocebus HIV Monkey SIV SIVagm Worobey grivet infected vervet

More articles from Life Sciences:

nachricht Nesting aids make agricultural fields attractive for bees
20.07.2017 | Julius-Maximilians-Universität Würzburg

nachricht The Kitchen Sponge – Breeding Ground for Germs
20.07.2017 | Hochschule Furtwangen

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

Leipzig HTP-Forum discusses "hydrothermal processes" as a key technology for a biobased economy

12.07.2017 | Event News

 
Latest News

Researchers create new technique for manipulating polarization of terahertz radiation

20.07.2017 | Information Technology

High-tech sensing illuminates concrete stress testing

20.07.2017 | Materials Sciences

First direct observation and measurement of ultra-fast moving vortices in superconductors

20.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>