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Shoudy LE, Namjoshi P, Giordano G, Kumar S, Bowling JD, Gelhaus C, Barry EM, Hazlett AJ, Hazlett BA, Cooper KL, Pittman PR, Reed DS, Hazlett KRO. The O-Ag Antibody Response to Francisella Is Distinct in Rodents and Higher Animals and Can Serve as a Correlate of Protection. Pathogens 2021; 10:pathogens10121646. [PMID: 34959601 PMCID: PMC8704338 DOI: 10.3390/pathogens10121646] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 11/16/2022] Open
Abstract
Identifying correlates of protection (COPs) for vaccines against lethal human (Hu) pathogens, such as Francisella tularensis (Ft), is problematic, as clinical trials are currently untenable and the relevance of various animal models can be controversial. Previously, Hu trials with the live vaccine strain (LVS) demonstrated ~80% vaccine efficacy against low dose (~50 CFU) challenge; however, protection deteriorated with higher challenge doses (~2000 CFU of SchuS4) and no COPs were established. Here, we describe our efforts to develop clinically relevant, humoral COPs applicable to high-dose, aerosol challenge with S4. First, our serosurvey of LVS-vaccinated Hu and animals revealed that rabbits (Rbs), but not rodents, recapitulate the Hu O-Ag dependent Ab response to Ft. Next, we assayed Rbs immunized with distinct S4-based vaccine candidates (S4ΔclpB, S4ΔguaBA, and S4ΔaroD) and found that, across multiple vaccines, the %O-Ag dep Ab trended with vaccine efficacy. Among S4ΔguaBA-vaccinated Rbs, the %O-Ag dep Ab in pre-challenge plasma was significantly higher in survivors than in non-survivors; a cut-off of >70% O-Ag dep Ab predicted survival with high sensitivity and specificity. Finally, we found this COP in 80% of LVS-vaccinated Hu plasma samples as expected for a vaccine with 80% Hu efficacy. Collectively, the %O-Ag dep Ab response is a bona fide COP for S4ΔguaBA-vaccinated Rb and holds significant promise for guiding vaccine trials with higher animals.
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Affiliation(s)
- Lauren E. Shoudy
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, NY 12208, USA; (L.E.S.); (G.G.)
| | - Prachi Namjoshi
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208, USA; (P.N.); (S.K.)
| | - Gabriela Giordano
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, NY 12208, USA; (L.E.S.); (G.G.)
| | - Sudeep Kumar
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208, USA; (P.N.); (S.K.)
| | - Jennifer D. Bowling
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15261, USA; (J.D.B.); (D.S.R.)
| | | | - Eileen M. Barry
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Allan J. Hazlett
- Department of Philosophy, Washington University, St Louis, MO 63130, USA;
| | - Brian A. Hazlett
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA;
| | - Kristine L. Cooper
- Hillman Cancer Center, Biostatistics Facility, University of Pittsburgh, Pittsburgh, PA 15261, USA;
| | - Phillip R. Pittman
- U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Fredrick, MD 21702, USA;
| | - Douglas S. Reed
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15261, USA; (J.D.B.); (D.S.R.)
| | - Karsten R. O. Hazlett
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, NY 12208, USA; (L.E.S.); (G.G.)
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208, USA; (P.N.); (S.K.)
- Correspondence: ; Tel.: +1-518-262-2338
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Pavkova I, Klimentova J, Bavlovic J, Horcickova L, Kubelkova K, Vlcak E, Raabova H, Filimonenko V, Ballek O, Stulik J. Francisella tularensis Outer Membrane Vesicles Participate in the Early Phase of Interaction With Macrophages. Front Microbiol 2021; 12:748706. [PMID: 34721352 PMCID: PMC8554293 DOI: 10.3389/fmicb.2021.748706] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/21/2021] [Indexed: 01/18/2023] Open
Abstract
Francisella tularensis is known to release unusually shaped tubular outer membrane vesicles (OMV) containing a number of previously identified virulence factors and immunomodulatory proteins. In this study, we present that OMV isolated from the F. tularensis subsp. holarctica strain FSC200 enter readily into primary bone marrow-derived macrophages (BMDM) and seem to reside in structures resembling late endosomes in the later intervals. The isolated OMV enter BMDM generally via macropinocytosis and clathrin-dependent endocytosis, with a minor role played by lipid raft-dependent endocytosis. OMVs proved to be non-toxic and had no negative impact on the viability of BMDM. Unlike the parent bacterium itself, isolated OMV induced massive and dose-dependent proinflammatory responses in BMDM. Using transmission electron microscopy, we also evaluated OMV release from the bacterial surface during several stages of the interaction of Francisella with BMDM. During adherence and the early phase of the uptake of bacteria, we observed numerous tubular OMV-like protrusions bulging from the bacteria in close proximity to the macrophage plasma membrane. This suggests a possible role of OMV in the entry of bacteria into host cells. On the contrary, the OMV release from the bacterial surface during its cytosolic phase was negligible. We propose that OMV play some role in the extracellular phase of the interaction of Francisella with the host and that they are involved in the entry mechanism of the bacteria into macrophages.
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Affiliation(s)
- Ivona Pavkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Jana Klimentova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Jan Bavlovic
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Lenka Horcickova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Klara Kubelkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Erik Vlcak
- Electron Microscopy Core Facility, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Helena Raabova
- Electron Microscopy Core Facility, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Vlada Filimonenko
- Electron Microscopy Core Facility, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia.,Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Ondrej Ballek
- Laboratory of Immunobiology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Jiri Stulik
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
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Krocova Z, Macela A, Kubelkova K. Innate Immune Recognition: Implications for the Interaction of Francisella tularensis with the Host Immune System. Front Cell Infect Microbiol 2017; 7:446. [PMID: 29085810 PMCID: PMC5650615 DOI: 10.3389/fcimb.2017.00446] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 09/29/2017] [Indexed: 12/11/2022] Open
Abstract
The intracellular bacterial pathogen Francisella tularensis causes serious infectious disease in humans and animals. Moreover, F. tularensis, a highly infectious pathogen, poses a major concern for the public as a bacterium classified under Category A of bioterrorism agents. Unfortunately, research has so far failed to develop effective vaccines, due in part to the fact that the pathogenesis of intracellular bacteria is not fully understood and in part to gaps in our understanding of innate immune recognition processes leading to the induction of adaptive immune response. Recent evidence supports the concept that immune response to external stimuli in the form of bacteria is guided by the primary interaction of the bacterium with the host cell. Based on data from different Francisella models, we present here the basic paradigms of the emerging innate immune recognition concept. According to this concept, the type of cell and its receptor(s) that initially interact with the target constitute the first signaling window; the signals produced in the course of primary interaction of the target with a reacting cell act in a paracrine manner; and the innate immune recognition process as a whole consists in a series of signaling windows modulating adaptive immune response. Finally, the host, in the strict sense, is the interacting cell.
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Affiliation(s)
- Zuzana Krocova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Ales Macela
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Klara Kubelkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
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