Ashley St. John

Prof. Ashley St. John is an expert in viral immunology and emerging infectious diseases, such as dengue and Zika viruses. She heads the Laboratory of Immunity and Immune Pathology at Duke-NUS Medical School.

Ashley St. John is an Assistant Professor at Duke-NUS Medical School and PI of the Laboratory of Immunity and Immune Pathology in the Programme in Emerging Infectious Diseases. She also holds appointments in the Department of Microbiology, National University of Singapore, Pathology Department, Duke University and SingHealth Duke-NUS Global Health Institute. 

Dr. St. John received her B.S. in Applied Biology from the Georgia Institute of Technology in 2004 and Ph.D. in Immunology from Duke University in 2010 before completing her post-doctoral training at Duke-NUS in 2014. She is an expert in viral immunology, with a focus on immunity to vector-borne pathogens such as dengue and Zika viruses. She also has a long-standing interest in lymphotropic pathogens that target to lymphoid tissue as a virulence strategy.

The St. John lab research program focuses on understanding host immune responses to virulent pathogens:

  • Innate and adaptive immune responses to dengue: Dengue is a mosquito-borne virus infection. We use immune competent mouse models to identify the ways the host immune system responds to dengue infection.
  • Mast cell responses to viral pathogens: Mast cells are best known for their involvement in conditions such as asthma, allergy and anaphylaxis, however, they also can provide immune surveillance for viral pathogens such as dengue virus. We are learning that MC responses to different viruses are highly unique. Several projects in the lab focus on understanding how mast cells contribute to immune protection and pathology during viral infection.
  • Flavivirus-induced vascular pathology: Many flaviviral pathogens induce immune pathology involving vascular and/or blood brain barrier leakage. We are particularly interested in the role of mast cell derived proteases in inducing vascular permeability or blood brain barrier permeability.
  • Vertical transmission of Zika virus infection: Zika virus is able to cross the placenta from mother to developing fetus. Members of our lab are investigating the mechanisms of vertical transmission of infection with emphasis on understanding how components of the immune system influence fetal infection.
  • Developing novel vaccination strategies, diagnostics, and therapeutics for infectious diseases: Highly host-adapted pathogens require specialized vaccine strategies for effective immune protection. We apply the knowledge gained in our basic research studies to develop novel vaccine strategies. We are also translating our findings that mast cell stabilizing drugs can limit dengue severity in animal models by working with collaborators at multiple institutions in Singapore to test whether mast cell stabilizing drugs can limit vascular leakage in dengue patients. 

Selected publications

Rathore, A.P.S., Saron, W.A.A., Lim, T., Jahan, N. and St. John, A.L. (2019) Maternal immunity and antibodies to dengue promote infection and Zika virus-induced microcephaly in fetuses. Science Advances. doi:10.1126/sciadv.aav3208

Masri, M.F.B., Mantri, C.K.M., Rathore, A.P.S., St. John, A.L. (2019) Peripheral serotonin causes dengue-induced thrombocytopenia through 5HT2 receptors. Blood. doi: 10.1182/blood-2018-08-869156 

Hsieh, J., Rathore, A.P.S., Soundarajan, G., St. John, A.L. (2019). Japanese encephalitis virus neuropenetrance is driven by mast cell chymase. Nature Communications. 10, Article number: 706 doi: 10.1038/s41467-019-08641-z 

Ashley St. John
Assistant Professor
Programme in Emerging Infectious Diseases
Academic discipline: 
News topics: