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| The Case: |
New York - 99 |
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Map of West Nile Virus
Ben called his old friend Lynn after hearing the latest count of people sick with West Nile Virus.
"Hey Lynn, you work in environmental health, what can you tell me about this West Nile Virus? We have a real epidemic going on here in Texas and everyone is saying it came from your state."
"I am so sick of New York being blamed. It's been around a lot longer, and it is called West Nile for a reason," Lynn explained. "It's true that the the virus was first detected in a dead flamingo and a sick horse in New York City in the summer of '99. But now it's all over the US. "
"It sure is - but, wait - a bird and a horse? I don't get it."
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Case Analysis
Issues include emerging diseases, identification of the virus, disease transmission, urban exposure, disease control, risk analysis, role of the media, etc.
Questions:
What's a sentinel species?
Why do crows get bit earlier?
What species of mosquito carries wnv?
How do you know if you have it?
Why does Texas have so many human wnv cases?
Why Minnesota?
What part of TX?
How is it contracted?
Is it contagious?
What kind of nucleic acid? RNA, DNA?
Has the strain mutated as it crossed the country?
Are there human receptor proteins?
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What do you know?
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What do you need
to know?
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Learning Goals
1. Value the use of molecular data to solve biological problems such as the likely source of the West Nile Virus
2. Identify the relationship between the nucleic acid sequence and the resulting glycoprotein.
3. Set up a Session (personal workspace) in Biology WorkBench to study nucleic acid sequences from several strains of West Nile Virus by utilizing import, alignment, and tree drawing tools to compare sequence data
4. Explain how comparing the selected sequences is used to track the likely source of the New York-99 strain
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Investigations and Activities
See the handout describing the use of the Biology WorkBench and a dataset of selected nucleic acid sequences to investigate the source of the New York WNV strains in 1999.
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will usually obtain additional references or resources to help
answer or explore their questions. |
Resources
CDC data set of WNV selected sequences
Alignment tools
Image of viral structure and fuction - specifically showing the role of the glycoprotein
Global Map
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Special Data Items
Centers for Disease Control and Prevention: West Nile Virus information
Campbell GL, Marfin AM, Lanciotti RS, and Gubler DG. West Nile virus. Lancet Infectious Diseases. 2002;2:519-29.
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Student Products
In lab, I would like the working groups to turn in their Know: Need to Know charts as well as the results using their subset of the CDC sequence data.
The full CDC sequence data would be made available. Students would be asked to discuss the implications of missing data in their attempt to pinpoint the origin.
Students (individuals or groups) would be asked to generate a list of five different uses of molecular data. They would identify the molecule being used, function, and source. A brief explanation of what is being compared and why would be included.
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Assessment and Evaluation Plan
I would like students to be able to support their conclusions about where the WNV strain found in New York in 1999 is likely to have originated by answering test questions about this process correctly.
Example 1: Explain why there was so much similarity between the WNV sequences you used in lab? What do the differences represent?
Example 2: Would any segment of nucleic acid from the different strains of West Nile Virus be as useful to compare as the segment you used in lab that codes for the glycoprotein? Explain.
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Implementation
This case is being adapted for use in a faculty workshop, but here is how I would use it in one course.
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Course name:
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Intro biology |
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Likely sequence in
syllabus:
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Just after introducing nucleic acids |
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Time during term:
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Second week |
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Duration:
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1 day |
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Setting:
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Lab activity |
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Students in course:
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Undergraduates |
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Collaborative elements:
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Students work in small groups with subsets of data. |
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Additional notes:
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The Know: Need to Know Chart is important, so give time to fill this out. |
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Credits
Map:www.cdc.gov/ncidod/dvbid/westnile
Viral structure: www.cdc.gov/ncidod/dvbid/westnile/resources/wnv-campbell-etal.pdf
Suchman, E. and M. Gallo. 2003. "Tracking the West Nile Virus" in Microbes Count!: Problem Posing, Problem Solving and Peer Persuasion in Microbiology. Jungck, J., M. Fass and E. Stanley, (Eds.). ASM Press. Washington, D.C.
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