Harlan D. Caldwell, Ph.D.

Chief, Chlamydial Diseases Section

Major Areas of Research

  • Pathogenesis of chlamydial infection
  • Immunity to chlamydial infection
  • Chlamydia vaccine development

Program Description

Chlamydia are important human pathogens that cause blinding trachoma and sexually transmitted disease for which vaccines are needed.  The focus of our research is to identify chlamydial virulence factors that function in the pathobiology of chlamydial host-cell interactions and evasion of host immunity.  We use in vitro and in vivo models of chlamydial infection together with comparative genomics, transcriptomics, proteomics, modern cell biology, and immunology to accomplish these goals.  This information is being used to design novel subunit and live-attenuated vaccines for the prevention of human chlamydial diseases.


Dr. Caldwell received his Ph.D. in pathobiology from the University of Washington in 1976. After completing a senior research fellowship in the Department of Medicine at the University of Washington in 1978, Dr. Caldwell joined the faculty of the University of California, San Francisco, as an assistant professor of microbiology and immunology. In 1980, he was recruited to the National Institutes of Health (NIH) as a tenure-track investigator in the Laboratory of Microbial Structure and Function. He became a tenured investigator in 1986 and chief of the Laboratory of Intracellular Parasites in 1990. He is a recipient of the NIH Director’s Award, NIH Merit Award, and PHS Superior Service Award. He was appointed to the NIH Senior Biomedical Research Service in 1997. Dr. Caldwell is a member of the editorial board of Infection and Immunity and a fellow of the American Academy of Microbiology. He is an internationally recognized leader in the fields of chlamydial pathogenesis and immunology.

Research Group

Yang Chunfu, Ph.D., Research Fellow
Marshall Collins, Post-baccalaureate IRTA Fellow
Li Ma, research assistant
Janice Chiou, research assistant

Selected Publications

Patton MJ, McCorrister S, Grant C, Westmacott G, Fariss R, Hu P, Zhao K, Blake M, Whitmire B, Yang C, Caldwell HD, McClarty G. 2016. Chlamydial protease activity factor and type III secreted effectors cooperate in inhibition of p65 nuclear translocation. mBio 7(5):e01427-16. doi:10.1128/mBio.01427-16.

Yang C, Starr T, Song L, Carlson JH, Sturdevant GL, Beare PA, Whitmire WM, Caldwell HD. 2015. Chlamydial lytic exit from host cells is plasmid regulated. mBio 6(6):e01648-15. doi:10.1128/mBio.01648-15.

Porcella SF, Carlson JH, Sturdevant DE, Sturdevant GL, Kanababandi K, Virtaneva K, Wilder H, Whitmire WM, Song L, Caldwell HD. Transcriptional profiling of human epithelial cells infected with plasmid-bearing and plasmid-deficient Chlamydia trachomatis.Infect. Immun. 2015 Feb 83:534-43.

Kari L, Southern TR, Downey CJ, Watkins HS, Randall LB, Taylor LD, Sturdevant GL, Whitmire WM, Caldwell HD. Chlamydia trachomatis polymorphic membrane protein D is a virulence factor involved in early host-cell interactions. Infect. Immun. 2014 Jul 82:2756-62.

Olivares-Zavaleta N, Whitmire WM, Kari L, Sturdevant GL, Caldwell HD. CD8+ T cells define an unexpected role in live-attenuated vaccine protective immunity against Chlamydia trachomatis infection in macaques. 2014. J. Immunol. May 192:4648-54.

Song L, Carlson J, Whitmire WM, Kari L, Virtaneva K, Sturdevant DE, Watkins H, Zhou B, Sturdevant GL, Porcella SF, McClarty G, Caldwell HD. Chlamydia trachomatis plasmid-encoded Pgp4 is a transcriptional regulatory of virulence-associated genes. Infect. Immun. 2013. 81:636-44.

Kari L, Whitmire WM, Olivares-Zavaleta N, Goheen MM, Taylor LD, Carlson JH, Sturdevant GL, Lu C, Bakios LE, Randall LB, Parnell MJ, Zhong G, Caldwell HD. A live-attenuated chlamydial vaccine protects against trachoma in nonhuman primates. J. Exp. Med. 2011. 208:2217-23.

Kari L, Goheen MM, Randall LB, Taylor LD, Carlson JH, Whitmire WM, Virok D, Rajaram K, Endresz V, McClarty G, Nelson DE, Caldwell HD. Generation of targeted Chlamydia trachomatis null mutants. Proc. Natl. Acad. Sci. USA. 2011. 108:7189-93.

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Content last reviewed on August 24, 2017