Laboratory of Eric J. Hansen, PhD

The virulence mechanisms that different pathogens use to circumvent or defeat host defense systems are mostly unknown or poorly understood. The Hansen laboratory is interested in elucidating the molecular bases of microbial virulence, which in turn will lead to new methods for prophylaxis and therapy of bacterial diseases.

Recombinant DNA methods are indispensable tools in the investigation of microbial virulence mechanisms. This technology, when used in conjunction with relevant model systems, can be employed to define the importance of specific gene products in the pathogenesis of bacterial infections. The Hansen laboratory utilizes molecular genetic systems, DNA microarray methods, and related technologies to study two different bacterial pathogens as prototypic microbial invaders. The first of these is Moraxella catarrhalis, a common cause of upper respiratory tract infection (i.e., otitis media) in infants and young children. The second is Haemophilus ducreyi, the etiologic agent of a sexually transmitted, genital ulcer disease known as chancroid. 

Research emphasis in the Hansen laboratory is placed on (1) the identification of bacterial genes that encode virulence factors, (2) the elucidation of the structure-function relationships inherent in these macromolecules, and (3) determination of how these bacterial factors subjugate host defense mechanisms. Our continuing studies include the precise construction of isogenic mutants whose virulence can then be evaluated in appropriate model systems and the development of new methods for the identification of additional virulence determinants.

Selected Publications

Deng, K., J.R. Mock, S. Greenberg, N.S.C. van Oers, and E.J. Hansen.  The Haemophilus ducreyi LspA proteins are tyrosine-phosphorylated by macrophage-encoded protein tyrosine kinases.  Infect. Immun. 76: 4692-4702 (2008).

Brooks, M.J., J.L. Sedillo, N. Wagner, C.A. Laurence, W. Wang, A.S. Attia, E.J. Hansen, and S.D. Gray-Owen. Modular arrangement of allelic variants explains divergence in Moraxella catarrhalis UspA protein function.  Infect. Immun. 76:5330-5340 (2008).

Wang, W., A.R. Richardson, W. Martens-Habbena, D.A. Stahl, F.C. Fang, and E.J. Hansen.  Identification of a repressor of a truncated denitrification pathway in Moraxella catarrhalis. J. Bacteriol. 190: 7762-7772 (2008).

Labandeira-Rey, M., D.M. Janowicz, R.J. Blick, K.R. Fortney, B. Zwickl, B.P. Katz, S.M. Spinola, and E.J. Hansen.  Inactivation of the Haemophilus ducreyi luxS gene affects the virulence of this pathogen in human subjects.  J. Infect. Dis. 200: 409-416 (2009).

Labandeira-Rey, M., J.R. Mock, and E.J. Hansen.  Regulation of expression of the Haemophilus ducreyi LspB and LspA2 proteins by CpxR.  Infect. Immun. 77: 3402-3411 (2009).

Labandeira-Rey, M., C.A. Brautigam, and E.J. Hansen.  Characterization of the CpxRA regulon in Haemophilus ducreyi.  Infect. Immun. 78: 4779-4991 (2010).

Hoopman, T.C., W. Liu, S.N. Joslin, C. Pybus, C.A. Brautigam, and E.J Hansen. Identification of gene products involved in the oxidative stress response of Moraxella catarrhalis.  Infect. Immun. 79:745-55 (2011).

Labandeira-Rey, M., D. Dodd, K.R. Fortney, B. Zwickl, B.P. Katz, D.M. Janowicz, S.M. Spinola, and E.J. Hansen. A Haemophilus ducreyi cpxR deletion mutant is virulent in human volunteers. Journal of Infectious Diseases, in press (2011).

Wang, W., T. Kinkel, W. Martens-Habbena, D.A. Stahl, F.C. Fang, and E.J. Hansen. The Moraxella catarrhalis nitric oxide reductase is essential for nitric oxide detoxification.  Journal of Bacteriology, in press (2011).