Francisella tularensis is a facultative intracellular bacterium that causes tularemia (a.k.a. rabbit fever), which when inhaled causes severe morbidity and mortality in human beings. After inhalation, the bacterium causes a fulminant bacterial pneumonia but also disseminates to a number of other tissues and organs including the spleen, lymph nodes, intestines, liver, kidney, bone marrow, and brain. Although macrophages and dendritic cells are thought to be a primary target of F. tularensis, the pathological mechanisms by which F. tularensis causes disease and death are not understood.
Because of the potential to cause disease when inhaled, tularemia is a potential biological weapon for which there are no licensed vaccines or antibiotics. We have successfully re-established the rabbit as a model of pneumonic tularemia that is relevant to the human disease. Within 3 days of exposure, naïve rabbits develop fever and begin losing weight. Erythrocyte sedimentation rate rises dramatically, an indicator of a robust inflammatory response. CBC results show a marked decline in lymphocytes and platelets in the blood. Radiographs show the development of a severe bacterial pneumonia in the rabbits. Naïve rabbits exposed to aerosolized virulent F. tularensis die between 4-7 days of infection.
In collaboration with Eileen Barry at the University of Maryland-Baltimore, we have used the rabbit model to evaluate attenuated strains of F. tularensis as possible vaccines. Three of these strains provided better protection than the existing vaccine candidate, the Live Vaccine Strain (LVS). The level of protection seen depends on the attenuated strain, the route of vaccination, and the number of vaccinations. Using an aerosol prime-boost vaccine approach we have achieved 83% survival with our lead vaccine candidate while LVS can only extend time to death. Serum IgG and IgM titers against F. tularensis in vaccinated rabbits correspond with the level of protection elicited. We are working with Dr. Barry and Dr. Karsten Hazlett of Albany Medical College to determine the antigens important for protection as well as the role of antigen persistence and inflammation. Our long term goals are 1) to determine the immunological mechanisms of protection responsible for the protection seen with these vaccines in order to design a subunit-based vaccine and 2) to understand the role of the host immune response in the outcome of disease.
In addition to the work on F. tularensis, we work with other investigators to develop animal models for aerosol exposure to infectious agents and to use those models to either understand pathogenesis or evaluate candidate vaccines and therapeutics. This includes not only natural respiratory pathogens (influenza, tuberculosis) but also pathogens that are biodefense threats. This includes development of nonhuman primate models for aerosol exposure to a number of highly pathogenic viruses including Highly Pathogenic Avian Influenza (HPAI), Venezuelan equine encephalitis virus (VEEV), western equine encephalitis virus (WEEV), eastern equine encephalitis virus (EEEV), and Rift Valley Fever virus (RVFV). In addition to doing aerosol exposures, we use radiotelemetry in the nonhuman primates to study the physiological response infection. This response can be used as an early indicator of outcome or as a means for determining efficacy of potential vaccines or therapeutics.
- O’Malley, K., Bowling, J.D., Hazlett, K.R.O., Barry, E.M., Reed, D.S. In Press. Development, characterization and standardization of a nose-only inhalation exposure system for exposure of rabbits to small particle aerosols containing Francisella tularensis. Infection & Immunity. PMID: 31085702
- O’Malley, K., Bowling, J.D., Stinson, E., Cole, K.S., Mann, B.J., Namjoshi, P., Hazlett, K.R.O.*, Barry, E.M.*, Reed, D.S.* 2018. Aerosol prime-boost vaccination with defined, attenuated mutants of type A Francisella tularensis provides strong protection in outbred rabbits against lethal aerosol challenge with virulent SCHU S4. PLoS ONE Oct 22;13(10):e0205928 PMID: 30346998 * - equal contribution
- Kim, A.S., Austin, S.K., Gardner, C.L., Zuiani, A., Reed, D.S., Trobaugh, D., Sun,C., Basore, K., Williamson, L.E., Crowe, J.E., Slifka, M.K., Fremont, D.H., Klimstra, W.B., Diamond, M.S. 2018. Protective antibodies against Eastern equine encephalitis virus bind to epitopes in domains A and B of the E2 protein. Nature Microbiology. PMID: 30455470
- Holland, K.M., Rosa, S.J., Kristjansdottir, K., Wolfgeher, D., Franz, B., Zarrella, T.M., Kumar, S., Sunagar, S., Singh, A., Bakshi, C.S., Barry, E.M., Sellati, T.J., Kron, S.J., Gosselin, E.J., Reed, D.S., Hazlett, K.R.O. 2017. Differential growth of Francisella tularensis, which alters expression of virulence factors, dominant antigens, and surface-carbohydrate enzymes, governs the efficacy of prophylactic immunization. Front Cell Infect Microbiol Jun 22;8:1158. doi: 10.3389/fmicb.2017.01158 PMID: 28690600
- Gardner, C.L., Sun, C., Luke, T., Raviprakash, K., Wu, H., Jiao, J., Sullivan, E., Reed, D.S., Ryman, K.D., Klimstra, W.B. 2017. Antibody preparations from human transchromosomic cows exhibit prophylactic and therapeutic efficacy versus Venezuelan equine encephalitis virus. J. Virol. Jun 26;91(14) PMID: 28468884
- Wonderlich, E.R., Swan, Z.D., Bissel, S.J., Hartman, A.L., Carney, J.P., O’Malley, K.J., Obadan, A.O., Santos, J., Walker, R., Sturgeon, T.J., Frye Jr., L.J., Maiello, P., Scanga, C.A., Bowling, J.D., Bouwer, A.L., Duangkhae, P.A., Wiley, C.A., Flynn, J.L., Wang, J., Cole, K.S., Perez, D.R., Reed, D.S., Barratt-Boyes, S.M. 2017. Widespread virus replication in alveoli drives acute respiratory distress syndrome in aerosolized H5N1 influenza infection of macaques. J. Immunol. 198(4):1616-26 PMID 28062701
- Stinson. E., Smith, L.P., Cole. K.S., Barry, E.M., Reed, D.S. 2016. Respiratory and oral vaccination improves protection conferred by the Live Vaccine Strain against pneumonic tularemia in the rabbit model. Pathog. Dis. 74(7):1-10 doi: 10.1093/femspd/ftw079 PMID: 27511964
- Abdelbaqi, S., Deslouches, B., Steckbeck, J., Montelaro, R., Reed, D.S. 2016. Novel engineered cationic antimicrobial peptides have a broad-spectrum activity against Francisella tularensis, Yersinia pestis, and Burkholderia pseudomallei. J. Med Microbiol. 65(2):188-94 PMID: 26673248
- Hartman, A.L., Powell, D.S., Bethel, L.M., Caroline, A.L., Schmid, R.J., Oury, T., Reed, D.S. 2014. Aerosolized Rift Valley Fever virus causes fatal encephalitis in African green monkeys and common marmosets. J. Virol. 88(4):2235-2245. PMID: 24335307
- Reed, D.S., Bethel, L.M., Powell, D.S., Hartman, A.L. 2014. Differences in aerosolization of Rift Valley Fever virus resulting from choice of inhalation exposure chamber: implications for animal challenge studies. Pathog Dis 71(2):227-233 PMID: 24532259
- Reed, D.S., Smith, L., Cole, K.S., Santiago, A.E., Mann, B.J., Barry, E.M. 2014. Live attenuated mutants of Francisella tularensis protect rabbits against aerosol challenge with a virulent type A strain. Infect Immun 82(5):2098-2105 PMID: 24614653
- Reed, D.S.*, Glass, P.J.*, Bakken, R.R., Barth, J.F., Lind, C.M., Hart, M.K., Rayner, J., Alterson, K., Custer, M., Dudek, J., Owens, G., Kamrud, K.I., Parker, M.D., Smith, J. 2014. Combined alphavirus replicon particle vaccine induces durable and cross-protective immune responses against equine encephalitic viruses. J. Virol. 88(20):12077-86 PMID: 25122801 *- equal contribution
- Faith, S.A., Smith, L.P., Swatland, A.S., Reed, D.S. 2012. Growth conditions and environmental factors impact aerosolization but not virulence of Francisella tularensis infection in mice. Front Cell Inf Microbio. 2(126):1-10. PMID: 23087911
- Reed, D.S., Smith, L., Dunsmore, T., Trichel, A., Ortiz, L.A., Cole, K.S., Barry, E. 2011. Pneumonic tularemia in rabbits resembles the human disease as illustrated by radiographic and hematological changes after infection. PLoS One. 6(9):1-9. PMID: 21931798
In my laboratory, we develop animal models for aerosol exposure to infectious agents (viruses and bacteria) that cause severe acute disease when inhaled. We use the world-class Aero3G aerosol management platform that offers maximum flexibility in choice of aerosol generators, sampling devices, and exposure chambers. Using a custom class III biological safety cabinet, we can safely expose animals to aerosols containing pathogenic agents. We can perform aerosol exposures on rodents, ferrets, rabbits, and nonhuman primates (both Old and New World species). For nonhuman primates and rabbits, we can monitor respiratory function in real time and relay that information to the Aero3G, which can adjust exposure duration to insure more uniform dosing between animals. Currently we have extensive experience generating aerosols containing influenza viruses (seasonal, pandemic, and avian), the encephalitic alphaviruses (Venezuelan, western, and eastern equine encephalitis viruses), Rift Valley Fever virus, Mycobacterium tuberculosis, Francisella tularensis, and Yersinia pestis. We have the capability to work with other BSL-3 agents and have strains available for work with Burkholderia pseudomallei, Burkholderia mallei, and Bacillus anthracis.
In addition to performing aerosol exposures, we use radiotelemetry to monitor, record, and analyze the physiological response to infection (e.g., fever and changes in ECG or EEG parameters). We use these models to understand the disease course and pathogenesis of these agents, and to evaluate the efficacy of candidate vaccines and therapeutics. Using fever, we were able to demonstrate that live attenuated and replicon-based vaccines prevented morbidity as well as mortality after challenge of cynomolgus macaques with encephalitic alphaviruses. We are currently exploring ECG and EEG changes in macaques that occur after exposure to encephalitic alphaviruses.
In collaboration with Eileen Barry at the University of Maryland-Baltimore, we have used the New Zealand White rabbit as a model to evaluate attenuated strains of F. tularensis as possible vaccines for protection against pneumonic tularemia. Three of these strains provided better protection than the existing vaccine candidate, the Live Vaccine Strain (LVS). The level of protection seen depends on the attenuated strain, the route of vaccination, and the number of vaccinations. Using an aerosol prime-boost vaccine approach we have achieved 83% survival with our lead vaccine candidate while LVS can only extend time to death. Serum IgG and IgM titers against F. tularensis in vaccinated rabbits correspond with the level of protection elicited. We are working with Dr. Barry and Dr. Karsten Hazlett of Albany Medical College to determine the antigens important for protection as well as the role of antigen persistence and inflammation in generating protective immunity. Our long term goals are 1) to determine the immunological mechanisms of protection responsible for the protection seen with these vaccines in order to design a subunit-based vaccine and 2) to understand the role of the host immune response in the outcome of disease.