Download Adenoviridae The Common Cold

ADENOVIRIDAE
THE COMMON COLD
Introduction
Today there are many viruses that effects the
human race. However, viruses can infect all
types of organisms including: animals, plants,
bacteria, and even archaea. One such virus is
known as adenoviridae. Adenoviruses are the
most common cause for acute upper
respiratory infections, or most generally
known as a “cold”. There are at least 51
human adenoviruses and the infection is most
common in the intestines, respiratory tract,
urinary tract, and the eyes. Adenoviruses
posses some interesting characteristics and
replicating strategies used to infect their
victim. Although adenoviruses can be
harmful, they are just as useful to scientists in
studying and preventing other diseases.
Characteristics
Adenoviruses are about 90 nm in diameter
and contain double-stranded DNA. The
structure of the adenovirus is quite simple
with no envelope and just a capsid, fibers,
core, and associated proteins. The capsid
contains 252 capsomeres and is icosohedral.
Figure 2: www.en.citizendium.org
Importance To Humanity
Although adenoviruses are uncomfortable
and may lead to other serious diseases,
they are also beneficial in curing diseases.
Viruses are parasites that usually
reproduce by infecting individual cells in
the human body, delivering their DNA to
the nucleus of those cells. Once there, the
viral DNA takes over the cell, and begins
to make more viruses. The cell will
eventually die, but will release more
viruses to continue the cycle. Scientists
can remove or disable some of the genetic
material of the virus, making it unable to
reproduce outside of the laboratory. This
genetic material can then be replaced by
the gene needed to treat a patient. The
reformed virus can then be administered
to the patient, where it will carry the gene
into the target cells. In this way, scientists
can take advantage of the virus’s ability to
deliver DNA to cells.
Conclusion
The next time you come down with a
cold, just remember it is a mediumsized, non-enveloped icosahedral virus
with double-stranded DNA. Although
you will be uncomfortable for a couple
weeks, the virus that has infected you is
also the virus that may just help
someone who is fighting a disease,
become cured.
Figure 6: www.fr.fotolia.com
Figure 4: www.sophisticatededge.com
•Figure 1: Adenovirus www.virology.net
The life cycle of an adenovirus has an early
and late phase. The virus attaches to a cell
with its fibers. The penton base proteins
interact with the host cell and is internalized
through endocytosis. The penton is
transported to the nucleus where it releases
its DNA and DNA replication begins. The late
phase begins when the late genes are
expressed during DNA replication. Viral
mRNA is transported to the cytoplasm and is
translated. Virus assembly begins at this
stage and finally the host cell dies and new
virus particles are released from the cell.
Adenoviruses can survive for long periods of
time outside of the body. They are highly
resistant to chemical and physical agents due
to their adverse pH conditions. Transmission
is usually through direct contact, fecal-oral
transmission, or waterborne transmission.
Scientists use recombinant
adenoviruses in experimental gene
therapy for muscle diseases, and can
deliver genes to almost all of the cells
in a small region surrounding the site
of injection. Currently, research is
being done to see if adenoviruses
could be used as a treatment for
cancer. After going through
extensive engineering to remove the
genes which control viral replication,
adenoviruses become very promising
for terminating tumor cells.
Figure 3: www.hindawi.com
Figure 5: www.usnationalsocietyofmed.com
References
Marieb, Elaine N. Human Anatomy &
Physiology. eighth edition. San Francisco,
California: Pearson Education, Inc., 2010.
773-774. Print.
Yoshida, et al, A. "Vaccine." Science Direct.
(2007): n. page. Print. <sciencedirect.com>.
United States. Centers for Disease Control and
Prevention. Adenoviruses. Atlanta, GA: ,
2010. Print. <cdc.gov>.
"Adenoviruses." Science Daily. (2010): n. page.
Print. <sciencedaily.com>.