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Name
Course
Professor
Date
Prions and Transmissible Spongiform Encephalopathies
Chemical and Molecular Structure of Prions
Prions are proteinaceous pathogens that cause transmissible spongiform encephalopathies
(TSEs) (Robertson np). The cellular prion protein (PrPc) concentrates in the central nervous
system of mammals. They are smaller than viruses, and only seen under electron microscope
after forming a cluster. Additionally, they are modified glycoprotein with a cell membrane
associated with the uptake of elements from the environment, essential for cell recognition. Prion
protein has two isoforms, which include PrPC
(normal isoform) and PrPSc
(the disease-associated
isoform). The difference between the two is seen in their secondary and tertiary structures. Thus,
the normal prion, PrPC
has an alpha helix formation. PrPSc
refolds from PrPC
to form a beta-
pleated sheet; hence, their tertiary structure changes according to the isoform (Kong 3101).

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Figure 1 the alpha helix of PrPC
and beta pleated sheet of PrPSc
(More on Prions np)
Treating Prions at a Molecular Level
Prions diseases include: kuru and bovine spongiform encephalopathy that attacks the
nervous system of human and cattle respectively. The proper medication for the condition is yet
to be established; thus, the current efforts are to develop means of reducing the pathogen’s
progression. In this regard, the proposed therapeutic strategies such as RNA interference (RNAi)
are intended to minimize the level of PrPC
and preventing its conversion into PrPSc
through the
ability of siRNA to degrade mRNA (Kong 3102). Another approach is the application of active
DNA vaccination to PrPC
. In fact, DNA immunization breaks the immune tolerance in prion
protein, leading to the induction of T-cell response and PrP-specific antibody.
Treating prions at a Chemical Level
Chemically modified phosphorothioate oligonucleotides (ASOs), is used to prevent the
formation of PrPSc
. It hinders the conversion of prions through binding PrPC
and inducing its

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endocytosis. Even though the treatment is fast, the reaction is very fatal and leads to death;
hence, not recommended until other alternatives are tried (Minikel np).
Side Effect of using RNAi and Active DNA in Prion Treatment
RNAi is capable of saturating the saturating the Argonaute proteins of RISC and
exporting hairpins from the nucleus, which further reduce the capability of long-term treatment
(Nielsen and Jørgen 470). On the hand, the use of active DNA has got no adverse effects to the
user.
Short and Long-Term Prognosis of Active DNA
Immunization delays the long-term effect. The rapid progression of the illness follows,
making it less effective in treating prions.

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Short and long term Prognosis of RNAi
The effectiveness of the drug to treat depends on best it targets and time the onset of the
disease. However, its prolonged usage has adverse effects on the tissue such as killing the
species subjected to the medication.
Preferred Treatment
Active DNA is the best method because when well timed, it delays the onset of the
disease. Besides, when compared to RNA and ASOs, there are no adverse effects associated with
the drug.

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Works Cited
Kong, Qingzhong. "RNAi: a novel strategy for the treatment of prion diseases." The Journal of
Clinical Investigation (2006): 3101–3103. Print.
Minikel, Eric Vallabh. "Updates on gene therapy for prion diseases." 18 May 2013. Web. 12
August 2015 <http://www.cureffi.org/2013/05/18/updates-on-gene-therapy-for-prion-
diseases/>.
"More on Prions." 2 July 2014. Web. 12 August 2015
<http://www2.cedarcrest.edu/academic/bio/hale/bioT_EID/lectures/madcowmoreprions.h
tml>.
Nielsen, Troels T and Jørgen E. Nielsen. "Antisense Gene Silencing: Therapy for
Neurodegenerative." Molecular Diversity Preservation International (2013): 457-484.
Print.
Robertson, Sally. "What is a Prion?" 20 July 2015.Web. 12 August 2015 <http://www.news-
medical.net/health/What-is-a-Prion.aspx>.

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Works Cited
Kong, Qingzhong. "RNAi: a novel strategy for the treatment of prion diseases." The Journal of
Clinical Investigation (2006): 3101–3103. Print.
Minikel, Eric Vallabh. "Updates on gene therapy for prion diseases." 18 May 2013. Web. 12
August 2015 <http://www.cureffi.org/2013/05/18/updates-on-gene-therapy-for-prion-
diseases/>.
"More on Prions." 2 July 2014. Web. 12 August 2015
<http://www2.cedarcrest.edu/academic/bio/hale/bioT_EID/lectures/madcowmoreprions.h
tml>.
Nielsen, Troels T and Jørgen E. Nielsen. "Antisense Gene Silencing: Therapy for
Neurodegenerative." Molecular Diversity Preservation International (2013): 457-484.
Print.
Robertson, Sally. "What is a Prion?" 20 July 2015.Web. 12 August 2015 <http://www.news-
medical.net/health/What-is-a-Prion.aspx>.