Lecture 4: Emerging Infections: How Epidemics Arise
by Donald E. Ganem, M.D.
Introduction by HHMI Vice President Dr. Joseph Perpich
Interview with Dr. Donald Ganem: What I like about being a scientist
How do new epidemics arise?
Genetic changes in viruses: Mutation and recombination
High rate of mutation in RNA viruses
Why do RNA-based genomes have a higher mutation rate?
Consequences of an elevated mutation rate
Influenza virus: Protein and genomic structure
Pathology of influenza
Influenza epidemics caused by antigenic drift
Influenza pandemics caused by antigenic shift
Genetic basis of antigenic drift
Molecular structure of hemagglutinin
Genetic basis of antigenic shift
Origin of different influenza hemagglutinin types
Animation: Recombination of viral RNA in a host cell
Where does recombination take place in nature?
Environmental changes can cause new epidemics: Hantavirus
Human migration affects epidemic patterns: Smallpox
Lesson learned from rabbits and myxoma virus in Australia
Less virulent myxoma strains emerge and maximize the spread of disease
Natural selection results in minimized susceptibility to disease
Comparing the myxoma virus in Australian rabbits and smallpox in Native Americans
What forces will shape the epidemics of the future?
Subtle changes affecting spread of diseases: Dengue fever and West Nile virus
Student questions
Closing remarks by HHMI Vice President Dr. Joseph Perpich
Closing remarks by HHMI President Dr. Purnell Choppin