ARLINGTON - Researchers led by Dr. Cédric Feschotte, assistant professor of biology at The University of Texas at Arlington, and assisted by Dr. Steven Goodman from the Field Museum in Chicago, have discovered that a retrovirus related to HIV became stably integrated into the genome of two different lemur species about 4.2 million years ago. The analysis of this ancient retrovirus, called pSIV for prosimian immunodeficiency virus, offers new insights into the evolution of lentiviruses including HIV, the causative agent of AIDS. The research will be published March 20 by the Public Library of Science (PLoS) Genetics. UT Arlington postdoctoral associate Clement Gilbert and undergraduate David Maxfield co-authored the paper.
Lentiviruses are a genus of viruses of the Retroviridae family that are characterized by a long incubation period. During replication, retroviruses integrate within the chromosomes of their host cells. If germ cells are infected, the integrated viral DNA can be transmitted from parent to offspring, and may eventually become assimilated as part of the genetic material of the host species. This "endogenization" process occurred repeatedly during evolution and has involved diverse retroviruses, giving rise to a sizeable portion of the genome of many vertebrate species, including about 8 percent of the human genome.
Until now, the process of endogenization was believed to be extremely rare for lentiviruses. The discovery that two different species of lemurs endemic to Madagascar suffered independently, and quasi-simultaneously, multiple germ line infections of pSIV challenges this perception. Based on ‘fossil' sequences collected from different lemur species, the researchers reconstructed computationally an apparently intact and complete DNA sequence for the ancestral prosimian lentivirus. These findings should allow future functional analysis of the extinct virus and advance understanding of the biology of lentiviruses, including HIV. In addition, the characterization of this ancient lentivirus in lemurs raises the possibility that HIV-like retroviruses are still circulating today in the mammalian fauna of Madagascar.
Go to www3.uta.edu/faculty/cedric for more information on Feschotte's research.
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