Download Different Mechanisms for Turning On Viral Protein Production in

Different Mechanisms for Turning On Viral Protein Production in Human Cells.
Ben Adams
Viruses are so simple they cannot be called living organisms. Instead they are referred to as
‘biological entities’, growing only by invading host cells and hijacking their metabolic
machinery. The human papillomavirus invades cells in the surface layers of the human body,
skin and mucosa, causing their uncontrolled growth. Normally these growths are not harmful
(benign) and are referred to as warts. However, some ´high risk` types of human papillomavirus
cause harmful (malignant) growth which can lead to cancer.
The human papillomavirus consists of DNA surrounded by a protein coat. Two proteins form
the coat: L1 and L2. Study of L1 is particularly important as this protein is recognised by the
body and this recognition helps the body ´fight back` against the virus. By exposing the body to
the L1 protein prior to infection, the body will be better equipped at destroying the virus if viral
invasion does occur.
In my research I have looked at different ways to produce the L1 protein in human cells grown
in the laboratory. Different forms of the L1 gene (encoding the L1 protein) were inserted into
circular DNA constructs called ´plasmids`. Human cells were infected with the plasmids to see
how much L1 protein each different L1 gene produced, by using the cellular machinery in much
the same way as the virus does.
To produce L1 protein from the gene, a switch or ‘promoter’ was required in front of the L1
gene in the plasmid to turn on L1 protein production in the human cells. I attempted to construct
plasmids containing the L1 gene under control of two different types of switch: one switch was
on all the time whilst the other could be turned on or off by adding a drug to the cells. I then
investigated how much L1 protein was produced from different forms of the L1 gene.
I was unable to successfully construct plasmids containing the L1 genes under the promoter that
was permanently on. Although plasmids containing the L1 genes under a drug-responsive
promoter were constructed successfully, no L1 protein expression was seen in human cells. This
was possibly due to problems getting the plasmids into the cells.
Human papillomavirus particles
Examensarbete i biologi, 10 p, spring 2002
Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University
Supervisor: Prof. Stefan Schwartz, PhD.