A hepatitis B-like virus has been found for the first time in fish. A
team of USGS researchers found the virus in white sucker from the Great
Lakes Region using gene-sequencing technologies.
How the recently discovered hepatitis B-like virus is transmitted
between fish is not yet understood, and it is unlikely to be
communicable to humans.
“To date, a hepatitis B virus has never been found before in fish and
we now have evidence that it infects fish in geographically distant
river systems in the Great Lakes region,” said lead author Cassidy Hahn,
a USGS scientist and graduate student at the University of West
Virginia. “This new virus is similar, but also very different from
hepatitis B-like viruses found in mammals and birds, and may be a new
genus.”
The hepatitis B virus is a small, spherical, enveloped virus,
previously known only in two groups--one that infects humans and other
mammals including orangutan, gibbons, gorillas and chimpanzee; and the
other that infects birds.
The white sucker is considered an indicator species, which is native
to river systems in the Midwestern and Northeastern United States. Their
widespread distribution and life-history have made them a target
species in numerous contaminant monitoring and effects studies. White
sucker are bottom feeders, spending most of their lives in close
proximity to the bottom of rivers, because of this they are in contact
with contaminants associated with the river bottom.
The DNA of an organism is like a recipe book for
making all of the proteins necessary for life. Those instructions are
coded as genes and are conveyed to protein making factories in the cell
via messenger ribonucleic acid molecules. In order to develop tools to
evaluate how these fish were utilizing their DNA (responding to their
environment), the RNA from liver tissue was sequenced using contemporary
high throughput RNA-sequencing methods. This approach allows for
decoding the usage of this blueprint.
In general, hepatitis-B viruses have a narrow host
range and infection manifests in various ways. In mammals, these viruses
infect and multiply in liver cells and are typically associated with
acute and chronic liver diseases including fibrosis, cirrhosis, bile
duct cancer, and hepatocellular carcinoma. It is estimated that 350
million people are chronically infected with HBV. Hepatitis B viruses in
birds are not normally associated with these liver diseases. The
potential effects on fish are currently unknown.
According to the research team, the hepatitis “B-like” virus found in
the fish is about as similar to the human hepatitis B virus as it is to
the bird hepatitis B viruses.
“This new virus may improve our understanding of the evolutionary
history of hepatitis B-like viruses,” said USGS biologist Luke
Iwanowicz, study coauthor. “There have been considerable scientific
efforts focused on identifying the origins of hepatitis B -like viruses.
The genome of this new virus has features not present in any known
virus from this family. It is a very exciting discovery.”
According to the researchers, the study may offer the opportunity to
develop a new model system to investigate host – pathogen interactions
and benefit human medical research.
Part of a joint U.S. Fish and Wildlife/USGS Great Lakes Initiative
Project, the study, Characterization of a Novel Hepadnavirus in the
White Sucker (Catostomus commersonii) from the Great Lakes
Region of the USA, by Cassidy M. Hahn, Luke R. Iwanowicz, Robert S.
Cornman, Carla M. Conway, James R. Winton, and Vicki S. Blazer is
available in the Journal of Virology online.
Source: http://www.usgs.gov/newsroom/article.asp?ID=4341#.VgXIniu1XwY Labels: fish virus, Research and Discoveries