Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. Earth Science News .




EPIDEMICS
Tracking the origins of HIV
by Staff Writers
Urbana IL (SPX) Dec 24, 2012


File image.

Human immunodeficiency virus (HIV) may have affected humans for much longer than is currently believed. Alfred Roca, an assistant professor in the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois, thinks that the genomes of an isolated West African human population provide important clues about how the disease has evolved.

HIV is thought to have originated from chimpanzees in central Africa that were infected with simian immunodeficiency virus (SIV), a retrovirus. "If you look at the diversity present across SIV in chimpanzees, it suggests that they have had it for tens of thousands of years," Roca said.

HIV-1 Type M, which accounts for 90 percent of human infections, is believed to have crossed the species barrier into human populations between 1884 and 1924. Roca said that it may have crossed much earlier and many times, selecting for genetic resistance in isolated rural populations while remaining undetected.

"Some of the scientific literature suggests that the persistence of HIV in humans required population densities typical of the larger cities that appeared in West Central Africa during the colonial era," he said.

Perhaps an even more important factor is that, before modern medicine and vaccinations, infectious diseases such as smallpox killed large numbers of people. People with compromised immune systems may have succumbed first, preventing the immunodeficiency virus from spreading.

If HIV crossed the species barrier many times, it is possible that selection favored protective genetic variants in the affected populations. Roca and his co-investigators looked for evidence of this selection in the Biaka genomes.

The Biaka are a human community that inhabits forests in the range of the chimpanzee subspecies believed to be the source of the current HIV pandemic. The researchers compared Biaka genomes with the genomes of four other African populations who live outside the chimpanzee's range.

Biaka genotypes were available through the Human Genome Diversity Project, which collected biological samples from 52 different population groups across the world. The project genotyped these diverse human communities for single nucleotide polymorphisms (SNPs, pronounced "snips"), or genomic variation, at around 650,000 locations across the genome.

Previous research that used cell lines made in the 1980s from individuals who had AIDS or were believed to be at risk for it had identified 26 genomic locations as being involved in resistance to HIV. Kai Zhao, a graduate student working in Roca's laboratory, examined these locations.

Zhao ran all 10 possible pairwise comparisons for the five human populations and looked for selection signatures. Specifically, selection for a genetic trait tends to reduce diversity in the surrounding genomic region within the affected population, increasing the differences between populations.

The researchers looked at the genomic regions that contain genes known to have a protective effect against HIV to see if there was any overlap with the selection signatures. Eight of the comparisons found overlap. Seven involved the Biaka.

They identified four genes in these overlaps that code for proteins affecting either the ability of HIV to infect the host cell or the disease progression. The researchers also found that for several genes, SNPs associated with protection against HIV-1 were common among the Biaka.

Roca cautions that these results should not be considered definitive. It is not possible to rule out false positives.

"You may detect a signature of selection, but it doesn't necessarily mean that selection has caused it. It's just a good sign that selection may have occurred," he said. Also, the signature of selection may span several genes, of which only one is actually protective against HIV-1.

However, he said that the results are intriguing and indicate that this line of research is worth pursuing.

"If additional studies confirm that these genes have undergone selection and that human populations in the region have some genetic resistance to HIV-1, one could try to find additional genes in the population that may also be protective against HIV but have not yet been identified," he said.

"The mechanism by which these genes work could be determined," he continued. "It could open up a new line of research for fighting retroviruses."

"Evidence for selection at HIV host susceptibility genes in a West Central African human populations" by Kai Zhao, Yasuko Ishida, Taras K. Oleksyk, and Alfred A. Roca has been recently published in BMC Evolutionary Biology.

.


Related Links
University of Illinois College of Agricultural, Consumer and Environmental Sciences
Epidemics on Earth - Bird Flu, HIV/AIDS, Ebola






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EPIDEMICS
WHO head warns diseases set to rise
Hong Kong (AFP) Dec 20, 2012
The head of the World Health Organization warned Thursday that infectious diseases will spread more easily in the future due to globalisation, changing lifestyles and rising population densities. "The future looks very bright for microbes, not so good for humanity," Margaret Chan told a luncheon in her hometown Hong Kong, the site of a major outbreak of the SARS virus in 2003 that killed al ... read more


EPIDEMICS
'No Christmas' for Philippine typhoon victims

Christmas misery in Haiti camp, three years after quake

360,000 Haitians still displaced after 2010 quake: IOM

'Apocalypse Noah': Dutch Christian readies escape Ark

EPIDEMICS
Berkeley Lab Scientists Developing Quick Way to ID People Exposed to Ionizing Radiation

All Systems Go for Highest Altitude Supercomputer

Space Fence program moving forward

Aldrich Materials Science discovers liquid-free preparation of metal organic frameworks

EPIDEMICS
Spanish consumers prefer national fish

Study reveals that animals contribute to seagrass dispersal

Slab of Barrier Reef sea floor breaking off: scientists

Study: Hawaiian island slowly dissolving

EPIDEMICS
W. Antarctic warming among world's fastest

Antarctic ice sheet warming faster than thought: study

NASA's Operation IceBridge Data Brings New Twist to Sea Ice Forecasting

Chief's hunger strike fuels Canada aboriginal drive

EPIDEMICS
A new, super-nutritious puffed rice for breakfast cereals and snacks

Can Observations of a Hardy Weed Help Feed the World?

The Green Revolution is wilting

Hungary bans foreign farmland ownership

EPIDEMICS
Cyclone risk in Indonesia said increasing

Chile volcano alert raised

Travel misery as floods hit Britain

Philippines typhoon death toll 'likely to hit 1,500'

EPIDEMICS
Chad lifts expulsion order against critical Italian bishop

Mali Islamists destroying more Timbuktu mausoleums

Peacekeepers warn of potential catastrophe in Darfur

Outside View: Tunisia's path ahead

EPIDEMICS
Scientists construct first map of how the brain organizes everything we see

Do palm trees hold the key to immortality?

Study: Human hands evolved as weapons

US shooting revives debate over videogame violence




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement