Assistant Professor

Contact Information:
Email:   stibbe@lsuhsc.edu
Office Phone:  318-675-8148
Laboratory Phone:  318-675-8149
Office Fax:  318-675-5764

Education/Training:
Postdoctoral Study, Washington University School of Medicine
Ph.D Microbiology, 1999, University of Kansas
B.S. Pharmacy, 1993, University of Kansas

Major Research Interests:  Pathogenesis of oncogenic viruses, virus-host interactions, host immunity to viruses, viral latency

Gammaherpesviruses such as Epstein-Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV) are associated with multiple diseases in humans, including lymphomas, carcinomas, and Kaposi’s sarcoma.  Murine gammaherpesvirus 68 (gammaHV68) is genetically related to EBV and KSHV and causes lymphoma in mice, providing a small animal model for mechanistic in vivo studies of the virus/host relationship.  Gammaherpesviruses evade the antiviral immune response by establishing a semi-dormant state called latency, facilitating life-long infection of the host.  Work in our laboratory is focused on dissecting the central role of latency in viral pathogenesis.  To facilitate these studies, we have generated mutant viruses that cannot lytically replicate but that may establish latency.  Using these viruses, we are defining the viral genes that are expressed during latency and determining their specific roles in both the viral life cycle and in modulating host immunity.  The long-term goal of these studies is to better understand the interplay between the antiviral immune response and latency, and to define how alterations in this relationship can result in the development of lymphoma.

Representative Publications:

Tibbetts, S., van Dyk, L., Speck, S., Virgin, H.  2002.  Immune control of the number and reactivation phenotype of cells latently infected with a gamma-herpesvirus.   J. Virol.  76:7125-7132.

Tibbetts, S., McClellan, J., Gangappa, S., Speck, S., Virgin, H.  2003.  Effective vaccination against long-term gamma-herpesvirus latency.   J. Virol.  77:2522-2529.

Tibbetts, S.*, Loh, J.*, van Berkel, V., Kapadia, S., McClellan, J., Jacoby, M., Speck, S., Virgin, H.  2003.  The establishment and maintenance of gamma-herpesvirus latency is independent of infective dose.  J. Virol.  77:7696-7701.     [*authors contributed equally to this work]

McClellan, J., Tibbetts, S., Gangappa, S., Brett, K., Virgin, H.  2004.  Critical role of CD4 T cells in an antibody independent mechanism of vaccination against gamma-herpesvirus latency.  J. Virol. 78:6836-6845.

McClellan, J., Braaten, D., Tibbetts, S., Virgin, H.  2005.  Control of chronic gamma-herpesvirus infection by non-classical MHC Class Ia-independent CD8 T cells.  Submitted.

Tarakanova, V., Suarez, F., Tibbetts, S., Jacoby, M., Weck, K., Hess, J., Speck, S., and Virgin, H.  2005. 
Murine gamma-herpesvirus 68 infection induces lymphoproliferative disease and lymphoma in BALB beta2 microglobulin deficient mice.  J. Virol. 79:14668-14679.

Steed, A., Barton, E., Tibbetts, S., Popkin, D., Lutzke, M., Rochford, R., Virgin, H.  2006.  Interferon gamma blocks gamma-herpesvirus reactivation from latency.  J. Virol. 80:192-200.

Braaten, D., McClellan, J., Messaoudi, I., Tibbetts, S., McClellan, K., Nikilich-Zugich, J., and Virgin, H.  2006.  Effective control of chronic gamma-herpesvirus infection by unconventional MHC Class Ia-independent CD8 T cells.  PLOS Pathogens. 2(5):e37.

Tibbetts, S., Suarez, F., Virgin, H.  2006.  A replication-defective gamma-herpesvirus establishes chronic infection in vivo and is impervious to T and B cell restriction.  Virology. 353:210-219.

Li, H., Ikuta, K., Sixbey, J., Tibbetts, S.  2008.  A replication-defective g-herpesvirus efficiently establishes long-term latency in macrophages but not B cells in vivo.  J Virol. 82:8500-8508.