Navigation Links
Hitchhiking virus confirms saga of ancient human migration
Date:10/21/2013

MADISON, Wis. A study of the full genetic code of a common human virus offers a dramatic confirmation of the "out-of-Africa" pattern of human migration, which had previously been documented by anthropologists and studies of the human genome.

The virus under study, herpes simplex virus type 1 (HSV-1), usually causes nothing more severe than cold sores around the mouth, says Curtis Brandt, a professor of medical microbiology and ophthalmology at the University of Wisconsin-Madison. Brandt is senior author of the study, now online in the journal PLOS ONE.

When Brandt and co-authors Aaron Kolb and Ccile An compared 31 strains of HSV-1 collected in North America, Europe, Africa and Asia, "the result was fairly stunning," says Brandt.

"The viral strains sort exactly as you would predict based on sequencing of human genomes. We found that all of the African isolates cluster together, all the virus from the Far East, Korea, Japan, China clustered together, all the viruses in Europe and America, with one exception, clustered together," he says.

"What we found follows exactly what the anthropologists have told us, and the molecular geneticists who have analyzed the human genome have told us, about where humans originated and how they spread across the planet."

Geneticists explore how organisms are related by studying changes in the sequence of bases, or "letters" on their genes. From knowledge of how quickly a particular genome changes, they can construct a "family tree" that shows when particular variants had their last common ancestor.

Studies of human genomes have shown that our ancestors emerged from Africa roughly 150,000 to 200,000 years ago, and then spread eastward toward Asia, and westward toward Europe.

Scientists have previously studied herpes simplex virus type 1 by looking at a single gene, or a small cluster of genes, but Brandt notes that this approach can be misleading. "Scientists have come to realize that the relationships you get back from a single gene, or a small set of genes, are not very accurate."

The PLOS ONE study used high-capacity genetic sequencing and advanced bioinformatics to analyze the massive amount of data from the 31 genomes.

The technology of simultaneously comparing the entire genomes of related viruses could also be useful in exploring why certain strains of a virus are so much more lethal than others. In a tiny percentage of cases, for example, HSV-1 can cause a deadly brain infection, Brandt notes.

"We'd like to understand why these few viruses are so dangerous, when the predominant course of herpes is so mild. We believe that a difference in the gene sequence is determining the outcome, and we are interested in sorting this out," he says.

For studies of influenza virus in particular, Brandt says, "people are trying to come up with virulence markers that will enable us to predict what a particular strain of virus will do."

The researchers broke the HSV-1 genome into 26 pieces, made family trees for each piece and then combined each of the trees into one network tree of the whole genome, Brandt says. "Ccile An did a great job in coming up with a new way to look at these trees, and identifying the most probable grouping." It was this grouping that paralleled existing analyses of human migration.

The new analysis could even detect some intricacies of migration. Every HSV-1 sample from the United States except one matched the European strains, but one strain that was isolated in Texas looked Asian. "How did we get an Asian-related virus in Texas?" Kolb asks. Either the sample had come from someone who had travelled from the Far East, or it came from a native American whose ancestors had crossed the "land bridge" across the Bering Strait roughly 15,000 years ago.

"We found support for the land bridge hypothesis because the date of divergence from its most recent Asian ancestor was about 15,000 years ago. Brandt says. "The dates match, so we postulate that this was an Amerindian virus."

Herpes simplex virus type 1 was an ideal virus for the study because it is easy to collect, usually not lethal, and able to form lifelong latent infections. Because HSV-1 is spread by close contact, kissing or saliva, it tends to run in families. "You can think of this as a kind of external genome," Brandt says.

Furthermore, HSV-1 is much simpler than the human genome, which cuts the cost of sequencing, yet its genome is much larger than another virus that also has been used for this type of study. Genetics often comes down to a numbers game; larger numbers produce stronger evidence, so a larger genome produces much more detail.

But what really jumped out of the study, Brandt says, "was clear support for the out-of-Africa hypothesis. Our results clearly support the anthropological data, and other genetic data, that explain how humans came from Africa into the Middle East and started to spread from there."

The correspondence with anthropology even extends, as before, to the details. In the virus, as in human genomes, a small human population entered the Middle East from Africa. "There is a population bottleneck between Africa and the rest of the world; very few people were involved in the initial migration from Africa," Brandt says. "When you look at the phylogenetic tree from the virus, it's exactly the same as what the anthropologists have told us."


'/>"/>

Contact: Curtis Brandt
crbrandt@wisc.edu
University of Wisconsin-Madison
Source:Eurekalert

Related biology technology :

1. UCLA researchers smartphone microscope can detect a single virus, nanoparticles
2. West Nile Virus Reported from New York to Long Beach; The Center for the Biology of Chronic Disease (CBCD) Urges the Public to Take Precautions
3. NanoBio To Present Data At ICAAC Supporting The Development Of Safe And Effective RSV & Herpes Simplex Virus-2 Vaccines
4. Redbiotec and TeselaGen to Partner on Herpesvirus Vaccine Library
5. Study puts troubling traits of H7N9 avian flu virus on display
6. The Majority of Physicians that Treat Hepatitis C Virus (HCV) Have Begun "Warehousing" and Preparing Their HCV Patients for the Next Generation of HCV Treatments
7. Global Virus Network Opens Headquarters in the University of Maryland BioPark
8. Antimicrobial Test Laboratories Emerges as Leading Provider of Virus Testing Services
9. Highly lethal Ebola virus has diagnostic Achilles heel for biothreat detection, scientists say
10. DiaCarta Inc. Receives CE Mark for QuantiVirus® HPV E6/E7 mRNA Assay
11. Acne Treatment Brand, Probiotic Action, Comments on the Use of a Virus to Treat Acne
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/2/2016)... ... 2016 , ... PhUSE will build on the huge success ... Day Events (SDE) to organize a multiple-day US conference. The first annual US ... the pharmaceutical and life sciences industry will cover industry standards, data science, regulations ...
(Date:12/2/2016)... KING OF PRUSSIA, PA (PRWEB) , ... December 01, 2016 , ... ... clinical research is through industry-wide collaboration, standardization and a beautiful technology experience. All three ... which convened more than 100 clinical trial leaders from over 40 sponsor, CRO and ...
(Date:12/2/2016)... ... December 02, 2016 , ... The ... to collaboratively developing improved chemistry, manufacturing and control technologies for the pharmaceutical ... with robust, probe-based sampling. , Online liquid chromatography analysis is becoming ...
(Date:12/2/2016)... YORK , Dec. 1, 2016   SurePure, ... photopurification, announced today that the Company has concluded an ... the right for a 90-day period to acquire units ... value of approximately USD 3.7 million.  ... agreement with Tamarack under which Tamarack will seek regulatory ...
Breaking Biology Technology:
(Date:11/15/2016)... DUBLIN , Nov 15, 2016 Research ... - Global Forecast to 2021" report to their offering. ... ... reach USD 16.18 Billion by 2021 from USD 6.21 Billion in ... Growth of the bioinformatics market is driven by ...
(Date:6/22/2016)... 22, 2016   Acuant , the ... solutions, has partnered with RightCrowd ® ... Visitor Management, Self-Service Kiosks and Continuous Workforce ... add functional enhancements to existing physical access ... venues with an automated ID verification and ...
(Date:6/15/2016)... 2016 Transparency Market Research ... Market by Application Market - Global Industry Analysis Size Share ... the report, the  global gesture recognition market  was ... is estimated to grow at a CAGR of ... Increasing application of gesture recognition technology ...
Breaking Biology News(10 mins):