Tais B. Saito, D.V.M., M.S., Ph.D.

Chief, Vector-Pathogen-Host Interaction Unit
NIH Distinguished Scholar

Major Areas of Research

  • Host immune components in establishment of vector borne infection and disease pathogenesis
  • Role of epidermal/dermal cells in vector transmission-associated inflammation
  • Dynamics of cutaneous immunoregulation during tick attachment and pathogen transmission
  • Role of vector transmission in development of pathogen specific immunity
  • Identification of determinants of disease severity in ehrlichial and rickettsial infection and their potential as immunotherapy
  • Identification of tick and bacterial factors associated with establishment of infection and bacterial persistence

Biography

Dr. Saito received a D.V.M. from the State University of Londrina, Parana, Brazil. She completed a residency in clinical practice and small animal surgery as well as a Master of Science degree at the same University.  Dr. Saito then earned her Ph.D. in veterinary medicine and infectious diseases at the State University of Sao Paulo, Brazil. In 2009, she moved to the U.S. to conduct postdoctoral research at the University of Texas Medical Branch at Galveston (UTMB). Later she was appointed as an Instructor at UTMB and as a Research Assistant Professor in 2017.  Dr. Saito was recruited to the DIR NIAID in 2020 as a tenure-track investigator, and is currently Chief of the Vector-Pathogen-Host Interaction Unit in the Laboratory of Bacteriology.   She serves as a review editor for Frontiers in Cellular and Infection Microbiology and as ad hoc reviewer for numerous journals in her field.  She is an advocate for diversity in the biomedical sciences.

Program Description

Environmental changes are driving a global increase in arthropod borne infections that, in many cases, cause severe life-threatening illnesses. An example in the United States is human ehrlichioses, an emerging infectious disease caused by Ehrlichia spp. An increase in tick borne infections and recognition of new pathogen species in recent years emphasize the importance of understanding the disease initiation and determinants of susceptibility. In 2009, a new species of Ehrlichia was detected in human patients in United States, Ehrlichia muris eauclairensis, transmitted by the tick vector Ixodes scapularis. These blood-feeding arthropods use their salivary proteins to manipulate the host local immune reaction at the bite site, facilitating prolonged attachment. Many pathogens, before and during transmission, are known to modulate the tick tissue environment, as well as their own transcriptome/proteome. Therefore, the induction of infection in the skin involves an extremely complex interaction of modulatory factors from the tick, pathogen and the host immune response.

Our research group is interested in understanding the immune signaling involved in vector transmission of pathogens, primarily focusing on tissue-specific innate host responses induced by ehrlichial (and rickettsial) diseases. We believe that this initial response, at the skin site of the tick-pathogen interaction with the host, is associated with disease development and progression to severe outcome.

Our animal model of ehrlichiosis, using the natural mode of infection by tick transmission, results in increased bacterial replication and dissemination throughout the body and more  severe outcome, compared to intradermal needle injection of ehrlichiae (Saito and Walker, 2015). The dermal reaction to tick inoculation of the ehrlichial pathogen demonstrates intense inflammatory infiltration and a strong IL-1 cytokine family signature. At the tick attachment site we observe intense tissue damage, with massive infiltration of granulocytes. The most impressive inflammatory infiltration is observed during the peak of tick feeding and after spontaneous detachment; however, we observed a dynamic response of the recruiting innate cells. Moreover, intradermal needle inoculation of bacteria did not induce extensive skin inflammation nor severe disease outcome. Similarly to other rickettsial infections, we identified a persistence of ehrlichial antigen at the skin of infected animals. These findings demonstrate induction of an inflammatory response, potentially associated with successful bacterial replication and disease pathogenesis.

Our ultimate goal is to better understand this complex vector-host-pathogen interaction at the cutaneous interface and its influence in immunopathogenesis of disease severity and/or development of protective immunity. By improving our knowledge of skin immune response to tick borne infections, we will be able to further evaluate the involvement of the initial immune-mediators on the development of dermal protective immunity to arthropod-transmitted diseases.

Selected Publications

Saito TB, Bechelli J, Smalley C, Karim S, Walker DH. Vector tick transmission model of spotted fever rickettsiosis. The American Journal of Pathology. 2019 Jan;189(1):115-123. doi: 10.1016/j.ajpath.2018.09.005. Epub 2018 Oct 11. PMCID: PMC6593257.

Smalley C, Bechelli J, Rockx-Brouwer D, Saito TB, Azar SR, Ismail N, Walker DH, Fang R. Rickettsia australis activates inflammasome in human and murine macrophages. PLoS One 2016 Jun 30;11(6):e0157231. doi: 10.1371/journal.pone.0157231. eCollection 2016. PMCID: PMC4928923.

Milhano N, Saito TB, Bechelli J, Fang R, Vilhena M, DE Sousa R, Walker DH. The role of Rhipicephalus sanguineus sensu lato saliva in the dissemination of Rickettsia conorii in C3H/HeJ mice. Medical and Veterinary Entomology 2015 Sep;29(3):225-9. doi:10.1111/mve.12118. Epub 2015 May 26. PubMed PMID: 26011701.

Saito TB, Walker DH. A tick vector transmission model of monocytotropic ehrlichiosis. The Journal of Infectious Diseases 2015 Sep 15;212(6):968-77. doi: 10.1093/infdis/jiv134. Epub 2015 Mar 3. PMCID: PMC4548458.

Saito TB, Thirumalapura NR, Shelite TR, Rockx-Brouwer D, Popov VL, Walker DH. An animal model of a newly emerging human ehrlichiosis. The Journal of Infectious Diseases 2015 Feb 1;211(3):452-61. doi: 10.1093/infdis/jiu372. Epub 2014 Jul 2. Erratum in: J Infect Dis. 2015 Jun 15;211(12):2025. PMCID: PMC4351372.

Shelite TR, Saito TB, Mendell NL, Gong B, Xu G, Soong L, Valbuena G, Bouyer DH, Walker DH. A hematogenously disseminated Orientia tsutsugamushi-infected murine model of scrub typhus. PLoS Neglected Tropical Diseases 2014 Jul 10;8(7):e2966. doi: 10.1371/journal.pntd.0002966. eCollection 2014 Jul. Erratum in: PLoS Negl Trop Dis. 2014 Aug;8(8):e3175. PMCID: PMC4091938.

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