Upending Conventional Wisdom, Certain Virus Families Are Ancient
ScienceDaily (Nov. 17, 2010) — Certain families of single-stranded DNA virus are more than 40 to 50 million years old, according to investigators from the Institute for Advanced Study, Princeton, NJ, and the Fox Chase Cancer Center, Philadelphia. The investigators found remnants of circoviruses and parvoviruses in the genomes of diverse vertebrates from fishes to birds and mammals that had been integrated into their genomes at different times from the recent past to more than 50 million years ago.
This electron micrograph depicts a number of parvovirus H-1 virions of the Parvoviridae family of DNA viruses. (Credit: CDC/R. Regnery; E. L. Palmer)
The research upends the conventional wisdom that most virus families are of very recent origin, and is published in the December Journal of Virology.
"Until recently, age estimates for all viruses except retroviruses were in the thousands of years, and nobody expected to be able to trace viruses beyond that time frame due to high mutation rates of the most commonly circulating viruses," says Anna Marie Skalka of Fox Chase. "We showed that several families have been around for tens of millions of years, and have barely changed over that time frame."
Viruses have long been speculated to be a source of novel animal genes, yet little evidence, except from retroviruses, has supported this idea. The team's motivation included the desire to search for such evidence in other viruses.
"We first scanned all published vertebrate genomes for traces of single stranded RNA (ssRNA) viruses other than retroviruses," says Skalka. The team then used a variety of techniques to devise a new method for determining the age of DNA sequences. "To our amazement, we discovered ancient fossils [viral sequences] in 19 vertebrate species that are related to certain currently circulating RNA viruses," notably the deadly Ebolaviruses, and the Bornaviruses, she says. These results, published earlier this year, encouraged these investigators to look for ancient fossils derived from ssDNA viruses.
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Journal of Virology, December 2010, p. 12458-12462, Vol. 84, No. 23
0022-538X/10/$012.00+0 doi:10.1128/JVI.01789-10
Copyright © 2010, American Society for Microbiology. All Rights Reserved.
Sequences from Ancestral Single-Stranded DNA Viruses in Vertebrate Genomes: the Parvoviridae andCircoviridae Are More than 40 to 50 Million Years Old
Vladimir A. Belyi,1 Arnold J. Levine,1* and Anna Marie Skalka2*
Simons Center for Systems Biology, Institute for Advanced Study, Einstein Drive, Princeton, New Jersey 08540,1 Institute for Cancer Research, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, Pennsylvania 191112
Received 24 August 2010/ Accepted 14 September 2010
Vertebrate genomic assemblies were analyzed for endogenous sequencesrelated to any known viruses with single-stranded DNA genomes. Numerous high-confidence examples related to the Circoviridae and two genera in the family Parvoviridae, the parvoviruses and dependoviruses, were found and were broadly distributed among 31 of the 49 vertebrate species tested. Our analyses indicate that the ages of both virus families may exceed 40 to 50 million years. Shared features of the replication strategies of these viruses may explain the high incidence of the integrations.
* Corresponding author. Mailing address for Anna Marie Skalka: Institute for Cancer Research, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111. Phone: (215) 728-2490. Fax: (215) 728-2778.
E-mail: am_skalka@fccc.edu.
Mailing address for Arnold J. Levine: Simons Center for Systems Biology, Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540. Phone: (609) 734-8005. Fax: (609) 951-4438.
E-mail: alevine@ias.edu
Published ahead of print on 22 September 2010.
Supplemental material for this article may be found at http://jvi.asm.org/.
Journal of Virology, December 2010, p. 12458-12462, Vol. 84, No. 23
0022-538X/10/$012.00+0 doi:10.1128/JVI.01789-10
Copyright © 2010, American Society for Microbiology. All Rights Reserved.
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