Exam 3 Flashcards
White-nose syndrome in bats is a ____ pathogen.
Fungal.
White-nose syndrome is currently found in…
33 states and 5 Canadian provinces, and is still spreading at an alarming rate.
Why do we care about bats?
They are pollinators and protectors of certain crops. Also, we care because we don’t want living things to die…obviously.
What causes White-nose syndrome? How does it kill?
Pseudogymnoascus destructans, or Pd destructans for short.
Pd destructans kills by causing dehydration and rapid heat loss, and increasing arousal (thus coming into contact with other bats more, spreading the disease) and causing an inability to feed. This disrupts hibernation and wing physiology.
Pd destructans is very environmentally persistant, meaning it can stay in reservoirs in the environment pretty rigorously.
How is WNS spread? Where did it come from?
It originated somewhere in France in 1918. People think it can be spread by raccoons, moths, and even mosquitos. However, it is primarily spread across the landscape by bats.
How are some ways people are mitigating the spread of WNS?
1) Biocontrol, by spreading certain bacterias that attack or inhibit Pd destructans.
2) UV light, which has been shown to weaken Pd as it is extremely sensitive to UV light.
3) Vaccines, obviously, that gives populations resistance to the disease.
What are prions?
“Proteinaceous infectious particles”.
Explain how PRPC –> PRPBSE, PRPCWD, or PRPSC.
PRP stands for “normal prion protein”. These proteins do not have a role that has been discovered yet, but the gene is not required for survival. It is usually a glycoprotein normally found at the cell surface in the plasma membrane.
When a PRPC meets a PRPBSE, it converts it to the abnormal form.
BSE, CWD, and SC are the diseases the misfolded proteins cause.
How are prions transmitted?
Firstly, a misfolded protein shows up (we dont entirely know how, as they aren’t living and they break a lot of fundamental biological principles).
This protein bumps into another and converts it to the misfolded form, which are highly resistant to most disinfectants, UV, heat, and radiation.
What is TSE?
Transmissible Spongiform Encephalitis. It affects the CNS, and can affect even humans.
It is caused by ingestion or inoculation, and is ALWAYS fatal. Slow progression.
How is TSE studied in mice?
1) 2 mice, one with PRPc and one with the gene knocked out (PRPko) were infected with PRPsc. Only the mouse with the PRPc gene were affected, meaning that without PRPc, PRPsc cannot spread.
2) Mice were expressing ovine, human, and bovine PRPc. When infected with PRPsc, only the ovine-expressing mouse was affected. We can study species barriers to transmission this way.
How do we diagnose TSE using histopathology?
Using “post mortem definitive diagnosis” - AKA, looking at the brain. It has a spongy-like appearance, vacuolated (exploded) neurons, plaques surrounded by vacuoles.
How do we diagnose TSE using immunochemistry?
Using antibodies specific for the prion protein antigens, which bind to it and stain it a certain color in tissue sections.
What is scrapie? What are the clinical signs?
A prion disease in sheep. It causes weight loss with a ravenous appetite, behavioral changes, excessive itching, rubbing, wool pulling and lip smacking and changes in gait.
Is there a genetic predisposition to scrapie?
Yes, it seems that the several variants of the PRNP gene can affect susceptibility or resistance to scrapie, and can also affect how long the disease incubates for.
What is BSE?
Bovine spongiform encephalitis. Depending on the dose ingested, the incubation period can be anywhere from 2-8 years.
The average age of onset tends to be 5 years.
Clinical signs include excitability, nervousness and aggression, sensitivity to noise, slow movement, and tremors.
What was the timeline of BSE outbreaks in europe, US and Canada?
1986, the first case confrmed.
1988, UK banned meat and bone meal from cattle feed.
1989, USDA bans importation of meat from countries with BSE.
1997, US & Canada ban ruminant products fed back to ruminants.
2001, EU ordered mandatory tests on cattle destined for slaughter.
2003, BSE found in washington state.
As of 2018, 6 cases of BSE in US. All have been sporadic and atypical.
What is Kuru?
Identified in New Guinea in 1900s, it was found in a tribe practicing cannibalism.
Women, children, and eldery infected 5x as often as men. The incubation period is also over 30 years.
What is CJD?
Creutzfeldt-Jakob disease. Age of onset usually 65 uears and kills in 4.5 months. It tends to be sporadic, but can also be inherited.
What is variant CJD?
CJD from consuming BSE contaminated foods, with the first case appearing in the UK in 1995.
Little is known, incubation period not known, nor is dose required. 28 years average age of onset, with duration being 13 months.
Possible genetic component, as all human cases have been homozygous at codon 129 of PRPC.
Initial symptoms are depression and schizophrenia-like psychosis, unsteady movements, progressively immobile and mute. No treatment available.
What is CWD?
A prion that affects deer, found in NA, Norway, and South Korea. Orginal epicenter in northeasternish Colorado.
Affects deer, no cases of human transmission YET. Does not YET appear to infect cattle.
Incubation is 12-64 months, but varies. Ingestion of prion from dirt or grass or contact with bodily fluids believed to transmit. Also believed to remain in the environment for long periods.
Causes weight loss, lack of coordination, drooping ears, and hypersalivation.
What are the differences in CWD infections in free vs captive populations?
Free rangings had slow proliferation, stable prevalence, and slow rates of diffusion, with a 10-15% infection rate.
Captive hers had faster dispersion, with an up to 79% infection rate. They can
What are some other examples of TSE?
Mink encephalopathy in MI and WI in 1947.
Feline encephalopathy, exclusively in the UK.
Exotic ungulate encephalopathy, exclusively in UK.
What are some ways to prevent TSE?
1) the FDA “animal feed rule” which bans using mammalian proteins as a source of food for ruminants.
2) 1989 import restriction on countries with BSE.
3) BSE testing of all rendered animals.
4) Surveilance, CWD testing, Scrapie National Eradication Program