Faculty & Staff bios

Greg Brennan, D.V.M., Ph.D.

Assistant Professor

College of Veterinary Medicine

E-Mail: gbrennan@westernu.edu

Phone: 8556

Join year: 2015


2008        Doctor of Philosophy, Microbiology

                University of Washington, Seattle, WA


2003       Doctor of Veterinary Medicine

               Colorado State University, Fort Collins, CO


2000        Bachelor of Science, Microbiology

                Colorado State University, Fort Collins, CO

Academic Interests

The spread of microbes from animals to humans has been responsible for most new infectious diseases in humans, including HIV, avian influenza, and SARS. Therefore, understanding how viruses adapt to infect a new species is critically important for public health, and may identify viruses poised to jump into a new species before an outbreak actually occurs.

The Brennan lab uses a multi-disciplinary approach including genomics, experimental evolution, and molecular biology to understand how viruses overcome antiviral immune proteins and infect new hosts. Our current findings suggest that gene amplification, as an initial adaptation, allows viruses to grow better in resistant host species, providing a foothold to enable further adaptations that are necessary for efficient replication and spread in the new host.

The current questions the lab is focused on include:

How do experimentally evolved mutations improve virus replication?

Experimental evolution is a powerful technique to define amino acid residues critical for host-virus interactions and to identify new virulence factors and host-range determinants. We are currently working to define the mechanism for mutations in two vaccinia virus genes that we recently discovered play a role in PKR evasion.

Is gene amplification a biomarker for viruses poised to cross species barriers?

We have shown that gene amplification in poxviruses can expand their host range in cell culture systems. Currently, only poxviruses have been shown to undergo gene duplication; however, there is substantial genetic evidence that other virus families may undergo similar adaptations.

What is the impact of host restriction factor diversity on individual susceptibility to infection?

Genetic variability in host restriction factors leads to a spectrum of individual antiviral phenotypes within a species. We are investigating the extent of genetic diversity within these important immune molecules. Our hypothesis is that certain genotypes within a species may provide sufficient selective pressure to drive gene amplification or other viral adaptations even before initial cross-species events.