Bacteriophages are
parasites of bacteria, and the world's most numerous
organisms. There are estimated to be 1031
phages worldwide. Compare that to 1021 stars
in the universe. Phages affect us in many different ways. For example,
half of
all bacteria are killed daily by phages. Many phages carry
virulence
factors for pathogenic diseases, such as cholera, diptheria
and scarlet
fever. Phages can also be used therapeutically
against pathogenic diseases. Many of the major
discoveries of the
molecular biology revolution were made possible using phages. Our mission is to understand bacteriophage development, life history, population dynamics and evolution. We also use phages as biological models for pathogenic viruses. Of particular interest is exploring the process of virus emergence and developing antiviral and antibacterial therapeutics.
Bacteriophage Life History
Because of their simplicity, bacteriophages make ideal organisms to explore life history evolution. The bacteriophage life cycle consists of three primary processes: attachment and entrance of, reproduction within, and exit from a host. We are involved in a systems biology approach to understanding how stochasticity in the phage host-lysis system and progeny assembly process affects fecundity and generation time. We use microscope-mounted perfusion chambers and fluorescent-activated cell sorting (FACS) to observe single cell dymanics of bacteriophage lambda infecting Escherichia coli. Students working on this project will receive training in molecular biology techniques such as site directed mutagenesis, PCR, protein expression analysis, vector construction, flow cytometry and sequence analysis as well as general microbiological techniques.
Bacteriophage Population Dynamics and the Emergence of Infectious Diseases
Fifty to
one hundred million people, or ~5% of
the world’s
population, died when the last major influenza pandemic swept the world
in 1918. Since then the world’s population has increased by
4.5
billion and its connectivity prompts the term “global
village”. If, in today’s world, direct contact
transmitted
HIV can cause ~60 million infections and ~30 million deaths, then a
highly virulent airborne virus would be catastrophic. Unfortunately it
is not a case of if, but when. Yet our understanding of emerging
infectious diseases has only increased superficially since 1918. We
still have no answers to basic questions. Why do some viruses, such as
HIV, spread pandemically through populations whereas others, such as
influenza A virus H5N1, appear briefly before petering out? This
question can be addressed using theory from evolutionary ecology. To
explore emergence from an evolutionary ecological perspective, we study
the dynamics of bacteriophage phi6 infection of a native host Pseudomonas phaseolicola and
a novel host P.
pseudoalcaligenes. The long term goal is to understand the
population dynamics of viral adaptation to new host types. Students involved
in this project will receive training in microbiological techniques,
PCR and sequence analysis.