My Fleep:
Health
Health
Using Viruses to Treat Disease.
We often hear on the news of recent outbreaks of a virus
somewhere or discussions of the impending Flu season.
Viral outbreaks are particularly difficult. Unlike
bacteria there is no antibiotic for a virus, because they
replicate inside of our cells. Those features which make
outbreaks difficult to control also make viruses good
candidates to be used by scientists to treat other diseases.
In the modern age of health care, there is a drug for just
about everything. However, if you suffer from a genetic
disease, the treatment options may not be as bright.
Unlike treating someone's symptoms with a drug, how do you
change someone's genetic makeup. One answer: gene therapy.
Still in its infancy, gene therapy is the insertion of
genes into an individual's cells to treat a disease. For
example, sickle cell anemia is a genetic disorder in which
the hemoglobin in your blood is defective, causing the cell
to have a different shape and not carry oxygen as well.
But if the DNA in the bone marrow could be replaced with
functional DNA, then the bone marrow would produce fully
functional red blood cells and the patient would be cured.
This is the potential of gene therapy. But how is this
replacement performed? In tissue culture, this process can
be accomplished relatively easily, using chemicals which
can fuse with the cellular membrane releasing encapsulated
DNA into the cell, but changing the DNA of a person is much
more difficult. To accomplish this task, scientists use
viruses to target specific organs and then deliver a
specific gene directly into the target cell, where it can
be used by the host to produce the correct protein or be
incorporated directly into the genome permanently. So how
does this work?
Unlike bacteria, viruses are intracellular parasites.
Bacteria are free living organisms capable of living and
replicating on their own outside of a human host. While
a virus is simply a capsule of genetic material (DNA or
RNA) covered in a protein coat. They do not contain the
enzymes or machinery to perform any metabolism outside of
their host cell. Because of this tight relationship, it is
very difficult to produce antibiotics that affect the virus
but not the cell. So when a virus comes in contact with
its host cell, it is taken up by the cell whereupon the
virus takes over control of the cellular machinery and
redirects its resources for normal activity to the
production of new viruses. With the completion of this
cycle, the newly formed viruses are released from the cell
back into the body to search out a new host. During this
process, if the host cell does not spontaneously die, the
virus will kill it.
This process has been modified so that once the virus has
been taken up by the cell, the DNA is released or
integrated into the genome. The virus never starts
replicating and the cell does not die. It is the ability
to deliver DNA directly into the cell and the ability to
control which tissues get the gene that makes viruses so
useful to gene therapy. Current research is involved in
being able to better package DNA and control more tightly
which cells a virus infects, but the future potential of
gene therapy is tremendous. All using microorganisms that
were once a source of disease, but now controlled for use
in the treatment of disease
----------------------------------------------------
Dr. Hoopes:
Virologist and Director of the National Reference
Laboratories (http://www.cytokinetesting.com).
We often hear on the news of recent outbreaks of a virus
somewhere or discussions of the impending Flu season.
Viral outbreaks are particularly difficult. Unlike
bacteria there is no antibiotic for a virus, because they
replicate inside of our cells. Those features which make
outbreaks difficult to control also make viruses good
candidates to be used by scientists to treat other diseases.
In the modern age of health care, there is a drug for just
about everything. However, if you suffer from a genetic
disease, the treatment options may not be as bright.
Unlike treating someone's symptoms with a drug, how do you
change someone's genetic makeup. One answer: gene therapy.
Still in its infancy, gene therapy is the insertion of
genes into an individual's cells to treat a disease. For
example, sickle cell anemia is a genetic disorder in which
the hemoglobin in your blood is defective, causing the cell
to have a different shape and not carry oxygen as well.
But if the DNA in the bone marrow could be replaced with
functional DNA, then the bone marrow would produce fully
functional red blood cells and the patient would be cured.
This is the potential of gene therapy. But how is this
replacement performed? In tissue culture, this process can
be accomplished relatively easily, using chemicals which
can fuse with the cellular membrane releasing encapsulated
DNA into the cell, but changing the DNA of a person is much
more difficult. To accomplish this task, scientists use
viruses to target specific organs and then deliver a
specific gene directly into the target cell, where it can
be used by the host to produce the correct protein or be
incorporated directly into the genome permanently. So how
does this work?
Unlike bacteria, viruses are intracellular parasites.
Bacteria are free living organisms capable of living and
replicating on their own outside of a human host. While
a virus is simply a capsule of genetic material (DNA or
RNA) covered in a protein coat. They do not contain the
enzymes or machinery to perform any metabolism outside of
their host cell. Because of this tight relationship, it is
very difficult to produce antibiotics that affect the virus
but not the cell. So when a virus comes in contact with
its host cell, it is taken up by the cell whereupon the
virus takes over control of the cellular machinery and
redirects its resources for normal activity to the
production of new viruses. With the completion of this
cycle, the newly formed viruses are released from the cell
back into the body to search out a new host. During this
process, if the host cell does not spontaneously die, the
virus will kill it.
This process has been modified so that once the virus has
been taken up by the cell, the DNA is released or
integrated into the genome. The virus never starts
replicating and the cell does not die. It is the ability
to deliver DNA directly into the cell and the ability to
control which tissues get the gene that makes viruses so
useful to gene therapy. Current research is involved in
being able to better package DNA and control more tightly
which cells a virus infects, but the future potential of
gene therapy is tremendous. All using microorganisms that
were once a source of disease, but now controlled for use
in the treatment of disease
----------------------------------------------------
Dr. Hoopes:
Virologist and Director of the National Reference
Laboratories (http://www.cytokinetesting.com).