Final Exam Flashcards
Prions are made of _______.
Proteins
Viroids only infect _______.
Plants
Prions cause _____.
TSEs. Transmissible spongiform encephalopathies.
(T/F) Prions invoke immune responses like viruses.
False
We discussed 5 kinds of human prion diseases. List them.
Kuru, CJD, vCJD, GSS, and FFI
We discussed 4 animal prion diseases. List them.
Scrapie, BSE, FSE, and CWD
Where did Kuru originate?
In the South Fore people.
South Fore people practiced _________, a likely cause for the emergence of Kuru.
Endocannabalism
Kuru was originally known as _______ sickness.
Laughing
In the 1950s, _______ traveled to New Guinea to study Kuru.
Gadjusek
Gadjusek was the first to say that Kuru is _________.
Transmissible
What are the 3 stages of Kuru infection?
Ambulant, Sedentary, and Terminal
What is the length of the incubation period for Kuru?
Very long incubation period
_______ initiated research on Kuru, CJD, and Scrapie in 1972, later winning a Nobel prize for isolating a single infectious particle he named “prion”
Pruisner
Prion stands for?
Proteinaceous infectious particle (PrP)
What are the 2 forms of a prion?
PrPc (normal cellular protein) and PrPres (mutated)
In 1994, _______ used a yeast protein called ____ as a model organism for prion work, helping Pruisner’s work to be accepted.
Wickner, Ure2P
(T/F) Prions are not very resistant to routine inactivation methods.
False
PrP is encoded by the ______ gene.
PRNP
How does PrPres destroy neurons in the brain?
By accumulating into clumps
The misfolded protein structure of a prion has a high content of _____ _____.
Beta sheets
How are more proteins misfolded after initial infection with a prion?
The misfolded protein molecule catalyzes the misfiling of other proteins
PrPc may bind to ______ and be shuttled into lysosomes where it is degraded.
Copper
Prions infect which 4 regions of the brain?
Cerebrum, cerebellum, thalamus, and spinal cord
What are the 3 ways TSEs can arise?
Infectious, sporadic, and inherited.
Which TSEs are inherited?
CJD, GSS, and FFI
Which TSEs are infectious?
vCJD, Kuru, and CJD acquired via iatrogenic infection
Which TSEs are sporadic?
Sporadic (normal) CJD
How do eaten prions travel from the stomach to the brain?
Via splanchnic or vagus nerves present in the abdominal region
(T/F) The infectious dose of a prion is unknown.
True
(T/F) Prions are known not to exist in the blood.
False.
Which form of CJD (vCJD vs. sporadic CJD) has a longer incubation period?
Sporadic CJD
What is the average age at death for vCJD patients?
28
What is the average age at death for sporadic CJD patients?
68
How does one make a definite diagnosis of vCJD?
Prion-positive immunostaining of biopsy material from tonsils, spleen, or lymph nodes
How can one make a definitive diagnosis of vCJD post-mortem?
Western blot analysis of brain tissue
Genetic studies are conducted to determine if a patient suspected of having vCJD is (homozygous/heterozygous) for _________ at codon ____.
Homozygous
Methionine
129
Upon autopsy, slices of brain contain _______ similar to a sponge after TSE infection.
Vacuoles
The PRNP gene exists at codons _____ and ____.
129 and 219
(T/F) Mutations in the PRNP gene result in spontaneous formation of PrPres.
True
Transmissibility of TSEs among same species is (easy/impossible). Explain why.
Easy. High degree of homology in prion protein
What is the likely origin of BSE?
Likely came from scrapie infected sheep, disease spread to cattle by eating contaminated bone meal derived from sheep offal
What is the likely origin of vCJD in humans?
Ingestion of beef contaminated with BSE agent.
______ ______ disease affects deer.
Chronic Wasting
Where do deer contract CWD?
From the environment. Environment serves as a stable reservoir for CWD prions (i.e. eating contaminated wheat grass)
What is the expression to prevent hunters from potentially spreading CWD to humans?
“No skull no backbone”
(T/F) There is no potential for CWD to transmiss to humans.
False.
Which species were used in early experimental CWD studies?
Squirrel monkeys and cynomolgus macaques.
Describe a plant viroid’s genome.
ssRNA covalently closed in a circular loop. High degree of internal base pairing
Plant viroids are (enveloped/naked)
Naked
Where do plant viroids replicate?
In the nucleus or chloroplast
Viroids replicate via a ______ _______ model.
Rolling circle
What is a good way to remember how viroids replicate?
Toilet paper
What kind of polymerase do plant viroids use?
RNA-dependent RNA polymerase
The only known human disease known to be caused by a viroid is _______.
Hepatitis D
Hepatitis D was originally ascribed to a defective virus called the ______ _____.
Delta agent
For Hepatitis D to occur, there must be simultaneous infection of a cell with both the _______ __ virus and the _______ __ viroid.
Hepatitis B virus,
Hepatitis D viroid
When Timothy Brown was diagnosed with both HIV and acute myeloid leukemia, he underwent a procedure known as _________ ____ _____ _________.
Hematopoietic stem cell transplantation
Doctors selected a (homozygous/heterozygous) _______-_____ for Timothy Brown
Homozygous CCR5-Δ32
Timothy Brown suffered from _____-_____-_____ disease and __________, both complications of transplant operations.
Graft-versus-host disease
Leukoencephalopathy
The _____-_____-_____ disease that Timothy Brown suffered from may have eliminated the HIV virus from his system.
Graft-versus-host disease
Define gene therapy.
Experimental treatment that involves introduction of genes into a person’s cells to REPLACE or COMPENSATE for defective genes that cause disease or medical problems
Genes can be delivered to cells via vectors such as _______ or ______.
Viruses or plasmids
In 1999, gene therapy experienced its first setback. _________ was one of 2 individuals where were administered 300 times the normal gene therapy virus vector dose.
Gelsinger
Gelsinger died as a result of ____-__ accumulation after gene therapy in 1999.
IL-6
In 2003, gene therapy experienced another major setback. 2 children developed ________ and died after retroviral gene therapy treatment for __-____.
Leukemia
X-SCID
In 2003, one of the boys who developed leukemia also experienced another phenomenon that caused uncontrolled cell division of his white blood cells. Why did this occur?
The modified retrovirus integrated into his genome into a gene regulating the normal cell cycle
Why is the size of the gene limited in gene delivery by viruses?
The patient may mount an immune response to viruses that are too large.
Viruses engineered for gene therapy must be ____ ____ specific.
Cell type
There are 4 hallmarks of a good gene delivery system. Describe them.
- Target the appropriate host cell
- Integrate the correct gene into the cell’s chromosomal DNA
- Transcribe and translate the gene of interest so that the gene product can
function properly - Cause no toxic or harmful effects
There are 2 methods used to target genes of interest in patent’s cells using viruses. Name them.
In vivo gene therapy
Ex vivo gene therapy
How does in vivo gene therapy work?
The patent’s body is directly infused or injected with the modified gene therapy viral vector.
(T/F) In vivo gene therapy is a scalable technique
True
How does ex vivo gene therapy work?
Patient’s cells are removed, grown in culture, infected with viral vector to introduce gene of interest, then infused back into patients
(T/F) Ex vivo gene therapy is a scalable technique.
False
Why is ex vivo gene therapy not a scalable technique?
Very expensive, requires highly specialized equipment that is not commonplace in hospitals.
Retroviruses (can/cannot) integrate into the cell’s genetic material.
Can
Adenoviruses (can/cannot) integrate into the cell’s genetic material.
Cannot
Adeno-associated viruses (can/cannot) integrate into the cell’s genetic material.
Can
Herpes Simplex Viruses (can/cannot) integrate into the cell’s genetic material.
Cannot
Vaccinia or poxviruses (can/cannot) integrate into the cell’s genetic material.
Cannot
Why is viral gene delivery preferred over plasmid gene delivery?
Plasmid delivery of genes is much less efficient
Cells can remove defective gene products via 3 kinds of molecules. Name them.
siRNAs, ribozymes, and antisense RNAs
Define xenotransplantation
Any procedure that involves the use of live cells, tissues, and
organs from a non-human source that are transplanted into humans or used for clinical Ex vivo perfusion
(T/F) Xenotransplantation includes transplantation of animal products such as pig insulin or pig heart valves.
False. Xenotransplantation does not include non-living animal products.
In 1960, _______ and _______ studied immune tolerance and rejection in animals and humans.
Medawar and Burnet
Medawar and Burnet’s research spearheaded ______ ______ development of immunosuppressive treatments to prevent organ rejection.
Tissue typing
________ was approved by the FDA in 1983 as an immunosuppressant.
Cyclosporin
What drives the development of xenotransplantation?
Shortage of human organ donors
Describe the HIV Organ Policy Equity (HOPE) program.
HIV infected individuals can donate organs to other HIV infected individuals
The majority of the illicit trade of organs is for which organ?
Kidneys
Why are pigs used for xenotransplantation as opposed to monkeys or apes? Describe 5 reasons.
- Pig organs are similar in size and physiology
- Pigs are readily available, can be bred easily
- Short gestation period
- Can be raised in a pathogen free environment
- Can be genetically modified to minimize rejection, making a more “human” pig
What are the 3 kinds of rejection?
Hyperacute, acute vascular, and chronic
In hyper acute rejection, the organ is dead within _________.
Minutes to hours
In acute vascular rejection, the organ is dead _________ after transplant.
Days to weeks
In chronic rejection, the organ dies __________ after transplant as a result of ________.
Months to years after transplant as a result of multiple acute rejections
1 solution to the problem of organ rejection is the creation of _______ ________ pigs.
Gene knockout
In gene knockout pigs, which gene is knocked out?
Alpha 1,3 galactose
1 solution to the problem of organ rejection is via continuous intravenous injection of ____________.
Alpha 1,3 galactose (natural or synthetic)
How is continuously injecting alpha 1,3 galactose into an organ transplant recipient a solution to organ rejection?
Sequesters antibodies
1 solution to the problem of organ rejection involves the insertion of _______ _____ __,__ ____________ __ _________ gene and ______ ________ _______ ___ gene into pig genomes
Human alpha 1,2 fucsyltransferase H transferase gene
Human complement inhibitor CD59 (hCD59) gene
What is the purpose of inserting human genes into a pig genome in organ transplantation research?
To make pig tissues look more like human tissues
Define xenozoonosis
A disease transmitted from an animal to human recipient after transplantation of an animal organ
In 2000, it was discovered that pigs harbor ______ __________ ________ _______ in their genomes.
Porcine endogenous retrovirus sequence
(T/F) Unlike HERVs, which can be activated into virus, PERVs are defective and cannot be activated into virus.
False.
There are 2 methods by which we can inactivate PERVs. Name them.
Usage of RNAi
Usage of CRIPR-Cas9
________virus reactivation is one of the most common infectious complications in immunosuppressed individuals
Herpesvirus
In 2004, an organ donor with _______ donated her organs to others. The recipients of the organs then contracted this disease.
Rabies
