Leptospirosis is the most widespread bacterial zoonosis, typically transmitted from reservoir host animals to humans via contaminated water. Leptospiral infection in humans frequently results in fulminant, life-threatening illness characterized by liver dysfunction, kidney failure, and pulmonary hemorrhage. Leptospirosis is emerging in tropical areas of the world undergoing rapid urbanization.

The focus of our research is to elucidate the molecular mechanisms of pathogenesis and immunity mediated by outer membrane proteins (OMPs). Our laboratory has developed strategies for membrane fractionation and identification of surface-exposed OMPs. We identified a family of leptospiral immunoglobulin-like repeat (Lig) proteins that are targeted by the human immune response to leptospirosis. When virulent leptospires are exposed to host-physiologic levels of osmolarity, expression of LigA and LigB is dramatically increased. We found that the LigA and LigB bind host extracellular matrix proteins, indicating roles for Lig proteins in host tissue colonization. Recent studies indicate that the Lig proteins are extremely promising immunodiagnostic and vaccine antigens.

For more information, visit the UCLA/VA Leptospirosis Research Website

Our second project is to develop electrochemical sensors for rapid bacterial pathogen identification and antibiotic susceptibility testing. Current culture-based diagnostic methods, which require 24-48 hours from specimen collection to readout, oblige clinicians to treat patients empirically with ever more potent antibiotics. New strategies are urgently needed to address the emerging global healthcare crisis of multidrug-resistant pathogens.

Our electrochemical sensor assay was developed by a multidisciplinary team of scientists who are leaders in the fields of electrochemistry, microbiology, microfluidics, and urology. The assay involves "sandwich" hybridization of target 16S rRNA to species-specific capture and detector probes. Horseradish peroxidase coupled to the detector probe provides a redox signal that is reported as electrical current. The assay can be performed at room temperature, has the sensitivity to defect as few as 100 bacteria, and can be performed in less than 30 minutes. Proof of concept has already been demonstrated in a clinical study of urine specimens from patients with urinary tract infections. The sensor assay can identify and quantitate pathogens in clinical specimens, and also assess the susceptibility of pathogens to antibiotics. We believe that rapid detection of drug-resistant bacterial pathogens would revolutionize the diagnosis and treatment of infectious diseases.

For more information, visit the Electrochemical Biosensor Project Website

Click here to search Pubmed for David A. Haake

Haake, D. A., Chao, G., Zuerner, R. L., Barnett, J. K., Barnett, D., Mazel, M., Matsunaga, J., Levett, P. N., and Bolin, C. A., "The leptospiral major outer membrane protein, LipL32, is a lipoprotein expressed during mammalian infection," Infect. Immun. 68:2276-2285 (2000).

Haake, D. A. "Spirochetal lipoproteins and pathogenesis," Microbiology 146:1491-1504 (2000).

Werts, C., Tapping, R. I., Mathison, J. C., Chuang, T.-H., Kravchenko, V., Saint Girons, I., Haake, D., Godowski, P. J., Hayashi, F., Ozinsky, A., Underhill, D., Aderem, A., Tobias, P. S., and Ulevitch, R. J., "Leptospiral endotoxin activates cells via a TLR2-dependent mechanism," Nature Immunology 2:346-352 (2001).

Haake, D. A., Dundoo, M., Cader, R., Kubak, B. M., Hartskeerl, R. A., Sejvar, S., and Ashford, D. A. "Leptospirosis, water sports, and chemoprophylaxis," Clin. Infect. Dis. 34:e40-3 (2002).

Cullen, P. A., Cordwell, S. J., Bulach, D. M., Haake, D. A., and Adler, B. "Global analysis of outer membrane proteins from Leptospira interrogans serovar Lai," Infect. Immun. 70:2311-8 (2002).

Haake, D. A. and Matsunaga, J. "Characterization of the leptospiral outer membrane and description of three novel leptospiral membrane proteins," Infect. Immun. 70: 4936-45 (2002).

Matsunaga, J., Barocchi, M., Croda, J. H. R., Young, T., Sanchez, Y., Siqueira, I. C., Bolin, C. A., Reis, M. G., Riley L., W., Haake, D. A., and Ko, A. I. "Pathogenic Leptospira species express surface-exposed proteins belonging to the bacterial immunoglobulin superfamily," Molecular Microbiology 49: 929-45 (2003).

Nascimento, A.L.T.O., Ko, A.I., Martins, E.A.L., Monteiro-Vitorello, C.B., Ho, P.L., Haake, D.A., et al. "Comparative genomics of two Leptospira interrogans serovars reveals novel insights into physiology and pathogenesis," J. Bacteriol. 186: 2164-72 (2004).

Haake, D. A., Suchard, M. A., Kelley, M. M., Dundoo, M., Alt, D. P., and Zuerner, R. L. "Molecular evolution and mosaicism of leptospiral outer membrane proteins involves horizontal transfer of DNA," J. Bacteriol. 186:2818-28 (2004).

Cullen, P. A., Haake, D. A., and Adler, B. "Outer membrane proteins of pathogenic spirochetes," FEMS Microbiology Reviews 28:291-318 (2004).

Matsunaga, J., Sanchez, Y., Xu, X., and Haake, D. A. "Osmolarity, a key environmental signal controlling expression and surface exposure of leptospiral proteins LigA and LigB and the extracellular release of LigA," Infect. Immun. 73:70-78 (2005).

Cullen, P., Xu, X., Matsunaga, J., Sanchez, Y., Mastali, M., Ko, A. I., Haake, D. A., and Adler, B. "The Surfaceome of Leptospira," Infect. Immun. 73:4853-63 (2005).

Setubal, J. C., Reis, M., Matsunaga, J., and Haake, D. A. "Lipoprotein computational prediction in spirochetal genomes," Microbiology 152:113-21 (2006).

Liao, J. C., Mastali, M., Gau, V., Suchard, M. A., Moeller, A., Bruckner, D., Babbitt, J. T., Li, Y., Gornbein, J., Landaw, E. M., McCabe, E. R. B., Churchill, B. M., and Haake, D. A. "Rapid species-specific detection of uropathogens using an electrochemical sensor array," J. Clin. Microbiol. 44:561-570 (2006).

Lo, M., Bulach, D. M., Powell, D. R., Haake, D. A., Matsunaga, J., Paustian, M. L., Zuerner, R. L., and Adler, B. "Effects of temperature on gene expression patterns in Leptospira interrogans serovar Lai as assessed by whole-genome microarrays," Infect. Immun. 74:5848-59 (2006).

Choy, H. A., Kelley, M. M., Chen, T. L., Matsunaga, J., and Haake, D. A. "Physiologic osmotic induction of Leptospira interrogans adhesion: LigA and B bind extracellular matrix proteins and fibrinogen" Infect Immun 75:2441-50 (2007).

Matsunaga, J., Lo, M., Bulach, D. M., M. L., Zuerner, R. L., Adler, B., and Haake, D. A. "Response of Leptospira interrogans to physiologic osmolarity: relevance in signaling the environment-to-host transition" Infect Immun 75:2864-74 (2007).

Croda, J., Ramos, J. G. R., Matsunaga, J., Queiroz, A., Homma, A., Riley, L. W., Haake, D. A., Reis, M. G., and Ko, A. I. "Leptospira Immunoglobulin-Like (Lig) proteins is a Serodiagnostic Marker for Acute Leptospirosis" J Clin Microbiol 45:1528-34 (2007).

Liao, J. C., Mastali, M., Yang, L., Gau, V., Suchard, M., Babbitt, J. T., Li, Y., Gornbein, J., Landaw, E. M., McCabe, E. R. B., Churchill, B. M., and Haake, D. A. "Development of an advanced electrochemical DNA biosensor for bacterial pathogen detection" J Mol Diag 9:158-68 (2007).

Silva, E. F., Medeiros, M. A., McBride, A. J., Matsunaga, J., Esteves, G. S., Ramos, J. B., Santos, C. S., Croda, J., Homma, A., Dellagostin, O. A., Haake, D. A., Reis, M. G., Ko, A. I. "The terminal portion of leptospiral immunoglobulin-like protein LigA confers protective immunity against lethal infection in the hamster model of leptospirosis" Vaccine 25:6277-86 (2007).

Stevenson, B., Choy, H. A., Pinne, M., Rotondi, M. L., Miller, M. C., DeMoll, E., Kraiczy, P., Cooley, A. E., Creamer, T. P., Brissette, C. A., Verma, A., Haake, D. A. "Leptospira interrogans endostatin-like outer membrane proteins bind host fibronectin, laminin, and complement regulatory factors" PLoS ONE 2:21188 (2007).

Ivancic, V., Mastali, M., Percy, N., Gornbein, J., Babbitt, J. T., Li, Y., Landaw, E. M., Bruckner, D. A., Churchill, B. M., Haake, D. A. "Rapid antimicrobial susceptibility determination of uropathogens in clinical urine specimens by use of ATP bioluminescence" J Clin Microbiol 46:1213-9 (2008).

Mastali, M., Babbitt, J. T., Li, Y., Landaw, E. M., Gau, V., Churchill, B. M., Haake, D. A. "Optimal probe length and target location for electrochemical detection of uropathogens at ambient temperature" J Clin Microbiol 46:2707-16 (2008)