Richard G. Titus
Professor

Phone: 491-4964
Fax: 491-0603
Email: Richard.Titus@colostate.edu
Office: 325 Pathology Building
Lab: 321 Pathology Building

 

Degrees

• BS, Northern Arizona University, 1972
• MS, University of Washington, 1976
• PhD, University of Washington, 1978

Research Interests

• The laboratory of Dr. Titus studies the immune response to pathogens (e.g., Leishmania) transmitted by arthropods and the immunosuppressive effects of the saliva of arthropods. Examples of ongoing projects are:
  • Following infection with L. major, mice develop a T cell response that can be either beneficial (Th1 cells which produce interferon-gamma) or detrimental (Th2 cells which produce interleukin-4) for the host. We are studying the mechanisms by which Th1 and Th2 cells are selectively activated so that vaccines for Leishmania can be developed which lead to the outgrowth of Th1 and not Th2 cells.
  • When sand flies inject Leishmania into the vertebrate host, they inject the parasite within their saliva. Sand fly saliva contains many proteins which help the fly obtain a bloodmeal. In addition, the saliva contains potent immunosuppressive proteins which can be critical to survival of the parasite within the host. Therefore, as an alternative approach for vaccinating against Leishmania, we are developing vaccines (both protein and DNA-based) against salivary proteins in an attempt to block the action of these proteins when the fly bites and thus to prevent infection with Leishmania.

Selected Publications

Pub Med for Titus RG.

• Brodskyn C, Beverley SM, Titus RG. 2000. Virulent or avirulent (dhfr-ts-) Leishmania major elicit predominantly a type 1 cytokine response by human cells in vitro. Clin. Exp. Immunol. 119:299-304.
• Chakkalath HR, Siddiqui AA, Shankar AH, Dobson DE, Beverley SM, Titus RG. 2000. Priming of a beta-galactosidase (betaGAL)-specific type 1 response in BALB/c mice infected with betaGAL-transfected Leishmania major. Infect. Immun. 68:809-814.
• Gillespie RD, Mbow ML, Titus RG. 2000. The immunomodulatory factors of bloodfeeding arthropod saliva. Parasit. Immunol. 22:319-331.
• Desbarats J, Stone JE, Lin L, Zakeri ZF, Davis GS, Pfeiffer LM, Titus RG, Newell MK. 2000. Rapid early onset lymphocyte cell death in mice resistant, but not susceptible to Leishmania major infection. Apoptosis. 5:189-196.
• Mbow ML, DeKrey GK, Titus RG. 2001. Leishmania major induces differential expression of co-stimulatory molecules on mouse epidermal cells. Eur. J. Immunol. 31:1400-1409.
• Gillespie RD, Dolan MC, Piesman J, Titus RG. 2001. Identification of an interleukin-2 binding protein in the saliva of the Lyme disease vector tick, Ixodes scapularis. J. Immunol. 166:4319-4327.
• Brodskyn CI, DeKrey GK, Titus RG. 2001. Influence of costimulatory molecules on the immune response to Leishmania major by human cells in vitro. Infect. Immun. 69:665-672.
• Mbow ML. Zeidner N, Gilmore RD Jr., Dolan M, Piesman J, Titus RG. 2001. MHC class II-independent generation of neutralizing antibodies against T-dependent Borrelia burgdorferi antigens presented by dendritic cells: regulation by NK and gamma delta T cells. Infect. Immun. 69:2407-2415.
• Titus RG, DeKrey GK, Morris RV, Soares MBP. 2001. Interleukin-6-deficiency influences cytokine expression in susceptible BALB mice infected with Leishmania major but does not alter the outcome of disease. Infect. Immun. 69:5189-5192.
• Cunningham ML, Titus RG, Turco SJ, Beverley SM. 2001. Regulation of differentiation to the infective stage of the protozoan parasite Leishmania major by tetrahydrobiopterin. Science. 292:285-287.
• Morris RV, Shoemaker CB, David JR, Lanzaro GC, Titus RG. 2001. Sand fly maxadilan exacerbates infection with Leishmania major and vaccinating against it protects against L. major infection. J. Immunol. 167:5226-5230.
• Rogers KA, DeKrey GK, Mbow ML, Gillespie RD, Brodskyn CI, Titus RG. 2002. Type 1 and type 2 responses to Leishmania major. FEMS Microbiol. Lett. 209:1-7.
• Guilpin VO, Swardson-Olver C, Nosbisch L, Titus RG. 2002. Maxadilan, the vasodilator/immunomodulator from Lutzomyia longipalpis sand fly saliva, stimulates hematopoiesis in mice. Parasite Immunol. 24:437-446.
• Guilpin VO, Nosbisch L, Titus RG, Swardson-Olver C. 2003. Infection with Leishmania major stimulates haematopoiesis in susceptible BALB/c mice and suppresses haematopoiesis in resistant CBA mice. Parasitol. 126:187-194.
• Rogers KA, Titus RG. 2003. Immunomodulatory effects of Maxadilan and Phlebotomus papatasi sand fly salivary gland lysates on human primary in vitro immune responses. Parasite Immunol. 25:127-134.
• DeKrey GK, Jones JJ, Mbow ML, Brodskyn CI, Titus RG. 2003. Requirement for B cells of delayed type hypersensitivity-like pathology after secondary infection with Leishmania major in resistant C57BL/6 mice. Amer. J. Trop. Med. Hyg. 69:481-483.
• Theodos CM, Morris RV, Jones JD, McMaster WR, Titus RG. 2004. Characterization of an I-E-restricted, gp63-specific, CD4 Th2 clone from resistant C3H mice that exacerbates infection with Leishmania major. Infect. Immun. 72:4486-4493.
• Costa DJ, Favali,C, Clarêncio J, Afonso L, Conceição V, Titus RG, Valenzuela J, Barral-Netto M, Barral A Brodskyn CI. 2004. Lutzomyia longipalpis salivary gland homogenate impairs cytokine production and costimulatory molecule expression on human monocytes and dendritic cells. Infect. Immun. 72:1298-1305.
• Rogers KA, Titus RG. 2004. The human cytokine response to Leishmania major early after exposure to the parasite in vitro. J. Parasitol. In press.
• Mejia JS, Moreno F, Muskus C, Vélez ID Titus RG. The surface-mosaic model in host-parasite relationships. Trends Parasitol. In press.
• Tonui, WK, Mbow ML, Mejia JS, Hochberg L, Chan AST, Ryan JR, Martin SK, Titus RG. Immunization with Leishmania major secreted/excreted (exo) antigens protects susceptible BALB/c mice against challenge infection with L. major. Infect. Immun. In press.
• Rogers KA, Titus RG. Leishmania major: Characterization of the early cellular immune response to the parasite in vitro using peripheral blood mononuclear cells from Leishmania-naïve humans. Amer. J. Trop. Med. Hyg. In press.