David D. Dunigan, Ph. D.

Research Assistant Professor University of Nebraska-Lincoln Department of Plant Pathology Nebraska Center for Virology 406 Plant Sciences Hall Lincoln, NE 68583-0722 Phone - 402.472.2858 Fax - 402.472.2853 ddunigan2@unl.edu

Research Interests:

Our research is focused on host-virus interactions, especially as it relates to pathogenesis. I have investigated several eukaryotic viral systems, including both plant and animal viruses. In considering virus infections generally, I have searched for common functions and events that tend to unite themes in virology, and these have included the ability of most viruses to capture the cellular machinery for protein and nucleic acid synthesis upon infection. One phenomena observed with many viruses is the rapid shutoff of host-directed macromolecular synthesis, while subverting the machinery and metabolic resources to the production of viral molecules. For RNA viruses, the major advantage is to gain metabolic energy and nucleotide pools, in as much that these viruses tend to encode their own polymerases. In addition to gaining energy and substrate molecules, DNA viruses may take advantage of the host polymerase functions directly, especially those lacking RNA polymerase (e. g., herpesviruses and chlorella viruses), by subverting host RNA polymerase II to transcribe the viral template to make the immediate-early transcripts.

The present work is in collaboration with Dr. James Van Etten, who is a “founding father” of the Phycodnavirus family, the type member being Paramecium bursaria chlorella virus-1 (PBCV-1). PBCV-1 is well characterized with respect to its large dsDNA genome (330 kb) and ~375 open reading frames. The virion is equally impressive with respect to size (190 nm diameter icosahedral particle, T = 169) and complexity. Evolutionarily, these viruses are related to other large DNA viruses, such as poxviruses, African swine fever virus, and the iridoviruses. We are investigating the proteome of the virion. Many of the virion-associated proteins have functions (or putative functions) that suggest the ability to control host macromolecular synthesis upon infection. Our current hypothesis is that virion-associated proteins are responsible for the immediate-early shutoff of host transcription in PBCV-1 infected Chlorella NC64A cells.

Knowledge of how and when viruses gain control of the host cells may lead to novel control methods, including the development of new anti-viral drugs and the mitigation of viral pathogenesis.

Selected Publications:

1. 1. Kang, M., Dunigan, D. D., Van Etten, J. L. (2005). Chloroviruses: A genus of Phycodnaviridae that infect certain Chlorella-like green algae. Molecular Plant Pathology, in press.
2. Awada, T., Dunigan, D. D., Dickman, M. B. (2004). Animal anti-apoptotic genes enhance recovery from drought stress in tobacco. International Journal of Agriculture & Biology 6:943-949.
3. Chen, S., Dunigan, D. D., Dickman, M. B. (2003) Bcl-2 family members inhibit oxidative stress-induced programmed cell death in Saccharomyces cerevisiae. Free Radicals in Biology and Medicine 34(10): 1315-1325.
4. Awada, T., Dunigan, D.D. and Dickman, M.B. (2003). Animal anti-apoptotic genes ameliorate the loss of turgor in water-stressed transgenic tobacco. Canadian Journal of Plant Sci. 83:499-506.
5. Sweat, J. M., Dunigan, D. D., Wright, S. E. (2001) Characterization of kidney epithelial cells from the West Indian manatee Trichechus manatus. In Vitro Cellular and Developmental Biology-Animal 37 (6): 386-394.
6. Redman, R. S., Dunigan, D. D., and Rodriguez, R. J. (2001) Fungal symbiosis from mutualism to parasitism: who controls the outcome, host or invader? New Phytologist 151(3): 705-716

Selected Abstracts:

1. Dunigan, D., Agarkova, I., Gurnon, J., Van Etten, J. L. (2004) Immediate-early Shutoff of Host Transcription in PBCV-1 Infected Chlorella Nc64A Cells: a Role for Virion-encapsidated Restriction Endonuclease Activity. Annual Meeting of The American Society for Virology, held at Montreal, Quebec.
2. Dunigan, D., Kelsch, D., Dickman, M. (2003) Heat Shock Protein 90 Is an Early Component of the Signal Transduction Cascade for Tobacco Mosaic Virus-Activated Programmed Cell Death. Annual Meeting of The American Society for Virology, held at Davis, California.
3. Dunigan, D., French, R. Park, Y-K., Dickman, M. (2001) Transgenic tobacco harboring animal anti-apoptotic genes alter virus-mediated pathogenesis. Annual Meeting of The American Society for Virology, held at Madison, Wisconsin.
4. Dunigan,D., French, R., Dickman M. B. (2001) Altered host response of tobaccos expressing human anti-apoptotic proteins to viral infection International Symposium for Molecular Plant-Microbe Interactions, held in Madison, Wisconsin.

Recent Invited Lectures:

2002
“ Tipping the life/death balance”
University of Nebraska, Lincoln, NE

2003
" Life and death decisions: The role of Hsp90 in TMV-mediated programmed cell death”
Oklahoma State University, Stillwater, OK

2004
“Tipping the life/death balance”
Nebraska Wesleyan University, Lincoln, NE