Research reveals potential reservoir species, new mechanism for how mammals acquire genes
(University at Buffalo)
BUFFALO, N.Y. -- Modern marsupials may be popular animals at the zoo and in children's books, but new findings by University at Buffalo biologists reveal that they harbor a "fossil" copy of a gene that codes for filoviruses, which cause Ebola and Marburg hemorrhagic fevers and are the most lethal viruses known to humans.
Published this week in the online journal BMC Evolutionary Biology, the paper ("Filoviruses are ancient and integrated into mammalian genomes") demonstrates for the first time that mammals have harbored filoviruses for at least tens of millions of years, in contrast to the existing estimate of a few thousand.
It suggests that these species, which maintain a filovirus infection without negative health consequences, could have selectively maintained these so-called "fossil" genes as a genetic defense.
The work has important implications for the development of potential human vaccines, as well as for the modeling of disease outbreaks and the discovery of emerging diseases, including new filoviruses.
"This paper identifies the first captured 'fossil' copies of filovirus-like genes in mammalian genomes," says Derek J. Taylor, PhD, associate professor of biological sciences in the UB College of Arts and Sciences and co-author. "Our results confirm for the first time that several groups of mammals, including groups such as marsupials that never colonized Africa, have had an association with filoviruses."
The UB co-authors say that if the rarely captured genes represent antiviral defenses or genomic scars from persistent infections, then the work opens up new possibilities for identifying reservoir species for filoviruses, which harbor the virus but remain asymptomatic. …
The research also demonstrates a new mechanism by which different species of mammals can acquire genes, through non-retroviral integrated RNA viruses, which the UB scientists had previously identified in eukaryotes but was unknown in mammals.
The UB scientists note that it is well-known that RNA retroviruses, like HIV-AIDS, can be integrated into mammal genomes.
"But because filoviruses infect only the cytoplasm of cells and not the nucleus and because they have no means of making DNA copies that might be integrated into the genome -- as retroviruses do -- it was never thought gene transfer could occur between non-retroviral RNA viruses and hosts," says Bruenn. "This paper shows that it does and it may prove to be a far more general phenomenon than is currently known." …