Patient Zero:
The Origins, Risks, and Prevention of Emerging Diseases
by
Andrew E. Lyman-Buttler
1. Explain how the molecular clock can act as a “tape measure” of evolution.
2. Describe how emergent diseases can spread into human
populations.
3. Evaluate the effects of social and cultural factors in the
transmission and understanding of disease.
4. Explain how the molecular biology of HIV allows it to infect target
cells.
5. Discuss the mechanisms of viral recombination, and explain its
role in the emergence of new diseases.
6. Describe one strategy for the prevention of new pandemics.
7. Outline the steps of the HIV reproductive cycle.
Learning Objectives
A new and deadly disease has emerged, causing symptoms unlike anything ever seen before…
1.As a class, list all the possible causes of disease.
2.Some diseases are transmissible from person to person.
List all the ways this might happen.
3.Epidemiologists can’t do controlled experiments on
human subjects (i.e., purposefully exposing people to suspected disease-causing agents).
An emerging pandemic…
4
Play Audio 1 0:00 to 6:04
http://www.radiolab.o rg/2011/nov/14/aids/
View the following animation (4:52) from the Howard Hughes Medical Institute that shows how HIV infects a cell and replicates itself using reverse transcriptase and the host's cellular machinery:
http://www.hhmi.org/biointeractive/disease/hiv_life_cycle.html
The molecular clock
6
Play Audio 2
6:04 to 10:04
1.
How does the molecular clock allow us to
determine the approximate time of origin of a
virus?
2.
What other viral infections have you heard of
that can infect other animals in addition to
humans?
3.
Why do you think these viruses are so
alarming to public health officials?
Spillover of influenza
View the following video lecture clip (1:18) on the origins of influenza virus strains.
http://media.hhmi.org/hl/99Lect4.html?start=29:02&end=30:21
Spillover of HIV
Play Audio 3
1. How was the world
changing in 1908?
2. How might these
conditions be relevant to the spread of an
infectious disease?
Part III – Why Then?
10
Recombination
Play Audio 4
Recombination
(example based on influenza virus)
View the following animation (3:05) from the
Howard Hughes Medical Institute that shows how two different strains of influenza can infect a
single cell to produce a new third strain of influenza:
http://www.hhmi.org/biointeractive/disease/recombination.html
1. How can non-human animals provide a pathway for
new viruses to enter the human population?
2. Consider the emergence of a pandemic, from the
first spillover event to worldwide transmission. Where are the points at which we could stop the spread of the disease? Which point would be
easiest?
Preventing the next pandemic
14
Play Audio 5
24:20 to end
1. Explain how the molecular clock can act as a “tape measure” of evolution.
2. Describe how emergent diseases can spread into human
populations.
3. Evaluate the effects of social and cultural factors in the
transmission and understanding of disease.
4. Explain how the molecular biology of HIV allows it to infect target
cells.
5. Discuss the mechanisms of viral recombination, and explain its
role in the emergence of new diseases.
1. Abumrad, J., and Krulwich, R. "Patient Zero: The Cell That Started a Pandemic."
Radiolab. 14 November 2011. WNYC. http://www.radiolab.org/2011/nov/14/aids/
2. Social network diagram (Slide 4): FMS - Sentinel Visualizer,
http://www.fmsasg.com, used with permission.
3. Howard Hughes Medical Institute 2007 Holiday Lectures: AIDS: Evolution of an
Epidemic. DVD.
4. Howard Hughes Medical Institute 1999 Holiday Lectures: 2000 And Beyond:
Confronting the Microbe Menace. DVD.
5. Diagram on Slide 7 & phylogeny on Slide 10: Hillis, David. "The Unexpected
Practical Applications of Evolutionary Biology." National Association of Biology Teachers Conference. Hyatt Regency Hotel, Dallas, TX. 2 November 2012. Lecture. Used with permission.
6. Scanning electron micrograph of HIV-1 budding (in green) from cultured
lymphocyte: C. Goldsmith, CDC. http://phil.cdc.gov/phil/details.asp?pid=10000
7. Africa 1908 map (Slide 11): Hemispheres Antique Maps & Prints. From Rand
McNally's Indexed Atlas of the World, 1908. http://www.betzmaps.com
8. Slide 15 images: Global Viral Forecasting Initiative: http://globalviral.org/
