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Franklin R. Toapanta Yanchapaxi, MD, PhD

Academic Title:

Associate Professor

Primary Appointment:



HSF-I 446

Phone (Primary):




Education and Training

Universidad Central del Ecuador School of Medicine (Honors and Distinction), M.D., 1998

University of Pittsburgh School of Medicine, Ph.D., 2006

Postdoctoral Fellow, University of Pittsburgh School of Medicine Center for Vaccine Research, 2006-2009

Postdoctoral Fellow, University of Maryland School of Medicine Center for Vaccine Development, 2009-2011


Dr. Toapanta is a vaccine immunologist and microbiologist interested in translational research. His work focuses on understanding the complex pathogen-host immune interactions to identify 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.

Dr. Toapanta studies the local (gut) and systemic immunity induced by enteric pathogens such as Salmonella Typhi and Shigella flexneri. To study systemic B and T cell responses, Dr. Toapanta uses clinical specimens from human vaccines and/or challenge studies combined with multi-color flow cytometry and mass cytometry (CyTOF). Local responses are explored in lamina propia mononuclear cells and mesenteric lymph node cells from non-human primates vaccinated and/or challenged with enteric pathogens. These studies focus on the identification of antigen-specific B cell responses, as well as cell mediated immune responses. The ultimate goal is to identify correlates of protection that will aid in novel vaccine design.

Immune response in the extremes of life are not optimal as evidenced by the limited immune responses to various vaccines by infants (< 1 year) and the elderly (>65 years). Dr. Toapanta is interested in the B cell compartment in the extremes of life to identify mechanisms involved in reduced response, which can provide targets to boost immune response in these populations.

Research/Clinical Keywords

Vaccine, immunology, microbiology, translational research, immune response, conjugated vaccines, therapeutic agents, enteric pathogens, B cell response, T cell response, salmonella, shigella.

Highlighted Publications

Toapanta FR, Bernal PJ, Fresnay S, Darton TC, Jones C, Waddington CS, Blohmke CJ, Dougan G, Angus B, Levine MM, Pollard AJ, Sztein MB. Oral wild-type Salmonella Typhi challenge induces activation of circulating monocytes and dendritic cells in individuals who develop typhoid disease. PLoS Negl Trop Dis. 2015 Jun 11;9(6):e0003837. doi: 10.1371/journal.pntd.0003837.

Boianelli A, Nguyen VK, Ebensen T, Schulze K, Wilk E, Sharma N, Stregemann-Koniszewski S, Bruder D, Toapanta FR, Guzman C, Meyer-Hermann M, Hernandez-Vargas EA. Modeling influenza virus infection: A roadmap for influenza research. Viruses. 2015;7(10):5274-5304; doi:10.3390/v7102875.

Price I, Mochan-Keef ED, Swigon D, Ermentrout GB, Lukens S, Toapanta FR, Ross TM, Clermont G. The inflammatory response to influenza A virus (H1N1): An experimental and mathematical study. J Theor Biol. 2015 Jun 7;374:83-93. doi: 10.1016/j.jtbi.2015.03.017.

Toapanta FR, Simon JK, Barry EM, Pasetti MF, Levine MM, Kotloff KL and Sztein MB. 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. 2014;5:374. doi: 10.3389/fimmu.2014.00374.

Booth JS*, Toapanta FR*, Salerno-Goncalves R, Patil S, Kader H, Safta A, Czinn S, Greenwald B, Sztein MB. 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. *Joint first authorship.

Additional Publication Citations

Hernandez-Vargas EA, Wilk E, Canini L, Toapanta FR, Binder S, Uvarovskii A, Ross TM, Guzmán CA, Perelson AS, Meyer-Hermann M. Effects of aging on influenza virus infection dynamics. J Virol. 2014 Apr;88(8):4123-31. doi: 10.1128/JVI.03644-13.

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. Differential response of the cynomolgus macaque gut microbiota to Shigella Infection. PLoS ONE 2013 Jun 5.

Davis CL, Wahid R, Toapanta FR, Simon JK, Sztein MB, et al. Applying mathematical tools to accelerate vaccine development: Modeling shigella immune dynamics. PLoS ONE 2013;8(4):e59465. doi:10.1371/journal.pone.0059465.

Toapanta FR, Bernal PJ, Sztein 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. 2013;2:128. doi: 10.3389/fcimb.2012.00128.

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.

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. Immunol Lett. 2010 Mar 10;129(1):32-8.

Toapanta FR, Ross TM. Impaired immune responses in the lungs of aged mice following influenza infection. Respir Res. 2009 Nov 18;10:112.

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.

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.

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.

Grants and Contracts