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Franklin R. Toapanta Yanchapaxi

Franklin R. Toapanta Yanchapaxi M.D., Ph.D.

Academic Title: Assistant Professor
Primary Appointment: Medicine
Location: HSF-I 446
Phone: 410-706-5328
Fax: 410-706-6205

Personal History:

Dr. Toapanta obtained his M.D. in Quito Ecuador (Universidad Central) and his Ph.D. from the University of Pittsburgh. He completed his first post-doctoral training at the Center for Vaccine Research of the University of Pittsburgh followed by training at the Center for Vaccine Development of the University of Maryland. Dr. Toapanta was promoted to Research Associate and subsequently to Assistant Professor in the Department of Medicine.

Research Interests:

Dr. Toapanta is a vaccine immunologist and microbiologists interested in translational research. Dr. Toapanta's research focuses on understanding the complex pathogen-host immune interactions with the objective of identifying key cellular and molecular players that can later be used as:

  1. Targets for the development of vaccines (protein, LPS and/or conjugated vaccines)
  2. Therapeutic agents

Identification of correlates of protection for Salmonella Typhi and Shigella flexneri , which are human restricted pathogens, have been elusive and seriously impaired the development of efficient novel vaccines for these microorganism. The B cell receptor (BCR) and T cell receptor (TCR) are extremely selective for the antigens they interact with. Antigenic ligation of the TCR and BCR start cell phosphorylation of highly regulated signaling cascades that lead to gene expression and therefore provide the first evidence of cell activation. Identification of the susceptibility of B and T cells to be activated (phosphorylated) by different antigens in primary as well as secondary infection or vaccination can help identify the more immunogenic components of a pathogen and therefore aid in vaccine design. Simultaneous phosphorylation of BCR and TCR associated signaling proteins are studied in primary cells of vaccinated volunteers using a novel multi-fluorescent flow cytometry technique (phosphoflow) that allows evaluation of complex samples.

Lab Techniques and Equipment:

Our lab uses various techniques to evaluate the immune responses including flow cytometry, mass cytometry, ELISA, ELISPOT, Western Blots, cytokine detection by multiplex assays. etc.


  1. Toapanta FR, Ross TM. Mouse strain-dependent differences in enhancement of immune responses by C3d. Vaccine. 2004 Apr 16;22(13-14):1773-81.
  2. Toapanta FR, Haas KM, Oliver JA, Poe JC, Weis JH, Karp DR, Bower JF, Ross TM, Tedder TF. Cutting Edge: C3d functions as a molecular adjuvant in the absence of CD21/35 expression. J Immunol. 2004 May 15;172(10):5833-7.
  3. Bright RA, Carter DM, Daniluk S, Toapanta FR, Ahmad A, Gavrilov V, Massare M, Pushko P, Mytle N, Rowe T, Smith G, Ross TM. Influenza virus-like particles elicit broader immune responses than whole virion inactivated influenza virus or recombinant hemagglutinin. Vaccine. 2007 May 10;25(19):3871-8
  4. Toapanta FR, Craigo JK, Montelaro RC, Ross TM. Reduction of anti-Gag immunity during co-immunizations: Immune interference by the HIV-1. Current HIV Research. 2007 March; 5(2):199-209.
  5. Bright RA, Carter DM, Crevar CJ, Toapanta FR, Steckbeck JD, Cole KS, Kumar NM, Pushko P, Smith G, Tumpey TM, Ross TM. Cross-clade protective immune responses to influenza viruses with H5N1 HA and NA elicited by an influenza virus-like particle. PLoS ONE. 2008 Jan 30;3(1):e1501.
  6. Toapanta FR, Ross TM. Impaired immune responses in the lungs of aged mice following influenza infection. Respir Res. 2009 Nov 18; 10:112.
  7. Toapanta FR, DeAlmeida DR, Dunn MD, Ross TM. C3d adjuvant activity is reduced by altering residues involved in the electronegative binding of C3d to CR2. Immunology Letters. 2010 Mar 10;129(1):32-8.
  8. Brown B, Price I, Toapanta FR, DeAlmeida DR, Wiley CA, Ross TM, Oury TD, and Vodovotz Y. An Agent-Based Model of Inflammation and Fibrosis Following Particulate Exposure in the Lung. Mathematical Biosciences. 2011 Jun;231(2):186-96. Epub 2011 Mar. 2011. PMID:21385589.
  9. Chen WH, Toapanta FR, Shirey KA, Zhang L, Giannelou A, Page C, Frieman MB, Vogel S, Cross AS. Potential role for alternatively activated macrophages in the secondary bacterial infection during recovery from influenza. Immunol Lett. 2012 Jan 30;141(2):227-34. Epub 2011 Oct 20.
  10. Toapanta FR, Bernal PJ, Sztein, and MB. Diverse phosphorylation patterns of B cell receptor-associated signaling in naive and memory human B cells revealed by phosphoflow, a powerful technique to study signaling at the single cell level. Front. Cell. Inf. Microbio. 2:128. doi: 10.3389/fcimb.2012.00128.
  11. Davis CL, Wahid R, Toapanta FR, Simon JK, Sztein MB, et al. (2013) Applying Mathematical Tools to Accelerate Vaccine Development: Modeling Shigella Immune Dynamics. PLoS ONE 8(4): e59465. doi:10.1371/journal.pone.0059465. Epub 2013 April 2.
  12. Anna M. Seekatz AM, Panda A, Rasko DA, Toapanta FR, Eloe-Fadrosh EA, Khan AQ, Liu Z1,7, Shipley ST, DeTolla LJ, Sztein MB, Fraser CM. (2013) Differential Response of the Cynomolgus Macaque Gut Microbiota to Shigella Infection. PLoS ONE. In press.
  13. Hernandez-Vargas EA, Wilk E, Canini L, Toapanta FR, Binder S, Uvarovskii A, Ross TM, Guzmán CA, Perelson AS, Meyer-Hermann M. The effects of aging on influenza virus infection dynamics. J Virol. 2014 Apr;88(8):4123-31. doi: 10.1128/JVI.03644-13. Epub 2014 Jan 29. PMID: 24478442
  14. Booth JS*, Toapanta FR*, Salerno-Goncalves R, Patil S, Kader H, Safta A, Czinn S, Greenwald B and Sztein MB (2014). Characterization and functional properties of gastric tissue-resident memory T cells from children, adults and the elderly. Front Immunol. 2014 Jun 19;5:294. doi: 10.3389/fimmu.2014.00294. eCollection 2014. PMID: 24995010. *Joint first authorship.
  15. Toapanta FR, Simon JK, Barry EM, Pasetti MF, Levine MM, Kotloff KL and Sztein MB (2014). Gut-homing conventional plasmablasts and CD27− plasmablasts elicited after a short time of exposure to an oral live-attenuated Shigella vaccine candidate in humans. Front. Immunol. 5:374. doi: 10.3389/fimmu.2014.00374