Inhibition of binding, entry, or intracellular proliferation of Ehrlichia risticii in P388D1 cells by anti-E. risticii serum, immunoglobulin G, or Fab fragment.
Abstract: The effects of equine antiserum, immunoglobulin G (IgG) specific for Ehrlichia risticii, and its Fab fragment on E. risticii binding to, internalization into, and proliferation in P388D1 cells were studied by immunofluorescence flow cytometry. Anti-E. risticii equine serum or IgG inhibited E. risticii at a stage beyond binding and internalization. In contrast, monovalent anti-E. risticii equine Fab fragments inhibited E. risticii binding and internalization into P388D1 cells. In the presence of control equine serum, IgG, or its Fab fragment, E. risticii cells were bound, were internalized and subsequently grew within P388D1 cells, and eventually destroyed the host cells as effectively as was the case without equine serum, IgG, or Fab fragments. Anti-E. risticii IgG but not normal horse IgG inhibited L-[14C]glutamine metabolism in Percoll gradient-purified E. risticii. These findings suggest that the Fab fragment of intact anti-E. risticii IgG blocks the ligands on E. risticii responsible for non-IgG-mediated internalization and diverts them to bind via the Fc receptor. Following Fc-mediated entry of E. risticii, the antibody interfered with the metabolic activity of E. risticii cells, rendering them incapable of proliferation in P388D1 cells and resulting in the eventual destruction of the organisms.
Publication Date: 1994-08-01 PubMed ID: 8039884PubMed Central: PMC302940DOI: 10.1128/iai.62.8.3156-3161.1994Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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This study examines how injections of horse antiserum, IgG antibodies, and a specific portion of the IgG antibody known as the Fab fragment can inhibit a harmful bacterium (Ehrlichia risticii) from infecting host cells. The research found that both equine antiserum and IgG can prevent the bacterial infection post-binding and internalization, while the Fab fragment can inhibit this process earlier, during the binding and internalization stages.
Introduction to the research paper
- The research focuses on understanding how equine antiserum, antibodies (Immunoglobulin G [IgG]), and antibody fragments (Fab) affect the lifecycle of the bacteria Ehrlichia risticii within P388D1 cells, a type of mouse monocyte/macrophage.
- Ehrlichia risticii is known to cause Potomac horse fever, a disease causing severe diarrhea in horses, and P388D1 cells are commonly used in research due to their similarities to human cells.
Experimental Approach
- The researchers studied the impact of three entities – equine antiserum, Anti-E. risticii IgG, and Fab fragments of the same on the progression of E. risticii infection.
- The progression of E. risticii infection involves stages such as binding to the host cells, internalization (penetration inside the cell), and proliferating inside the cells.
- The researchers used immunofluorescence flow cytometry, a technique used to measure physical and chemical characteristics of a cell or particle, to observe the effects of these substances on the infection process.
Findings
- Anti-Ehrlichia risticii equine serum and the IgG form of this antibody affected the bacteria after they had already attached to and entered the P388D1 cells, halting their proliferation within the cells.
- In contrast, the monovalent equine Fab fragments of Anti-Ehrlichia risticii acted earlier in the bacteria’s lifecycle, by inhibiting the bacteria’s attachment and entry into the host cells.
- In the control group (absence of antiserum, IgG, or Fab fragments), the bacteria were capable of attaching, entering, growing within the P388D1 cells, and eventually causing cell destruction.
- Interestingly, Anti-E. risticii IgG inhibited the metabolism of E. risticii. The glutamine metabolism, a process essential for bacterial survival and multiplication, was blocked by the IgG which was not seen with normal horse IgG.
- This data indicates that the Fab portion of the Anti-E. risticii IgG blocked key entry points (ligands) on the bacteria that caused cell penetration and redirected them to bind to other receptors (Fc receptors).
- Following this redirected entry, the antibodies were still capable of disrupting the metabolic activity of E risticii, thereby making them unfit for multiplication within the P388D1 cells and leading to their destruction.
Conclusions
- The study offers a potentially new method for prevention and treatment of infections caused by E risticii. It unveils how antibodies and their fragments could be used to undercut critical metabolic processes in the bacteria, thus making them incapable of sustaining within host cells.
Cite This Article
APA
Messick JB, Rikihisa Y.
(1994).
Inhibition of binding, entry, or intracellular proliferation of Ehrlichia risticii in P388D1 cells by anti-E. risticii serum, immunoglobulin G, or Fab fragment.
Infect Immun, 62(8), 3156-3161.
https://doi.org/10.1128/iai.62.8.3156-3161.1994 Publication
Researcher Affiliations
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Ohio State University, Columbus 43210-1092.
MeSH Terms
- Animals
- Antibodies, Bacterial / immunology
- Carbon Dioxide / metabolism
- Ehrlichia / immunology
- Glutamine / metabolism
- Horses
- Immune Sera / immunology
- Immunoglobulin Fab Fragments / immunology
- Immunoglobulin G / immunology
- Leukemia P388 / microbiology
- Mice
- Neutralization Tests
- Tumor Cells, Cultured
Grant Funding
- R01 AI30010 / NIAID NIH HHS
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Citations
This article has been cited 10 times.- Contreras M, Alberdi P, Mateos-Hernández L, Fernández de Mera IG, García-Pérez AL, Vancová M, Villar M, Ayllón N, Cabezas-Cruz A, Valdés JJ, Stuen S, Gortazar C, de la Fuente J. Anaplasma phagocytophilum MSP4 and HSP70 Proteins Are Involved in Interactions with Host Cells during Pathogen Infection.. Front Cell Infect Microbiol 2017;7:307.
- Stuen S, Okstad W, Artursson K, Al-Khedery B, Barbet A, Granquist EG. Lambs immunized with an inactivated variant of Anaplasma phagocytophilum.. Acta Vet Scand 2015 Jul 25;57(1):40.
- Gibson K, Kumagai Y, Rikihisa Y. Proteomic analysis of Neorickettsia sennetsu surface-exposed proteins and porin activity of the major surface protein P51.. J Bacteriol 2010 Nov;192(22):5898-905.
- Huang H, Wang X, Kikuchi T, Kumagai Y, Rikihisa Y. Porin activity of Anaplasma phagocytophilum outer membrane fraction and purified P44.. J Bacteriol 2007 Mar;189(5):1998-2006.
- Casadevall A. Antibody-mediated immunity against intracellular pathogens: two-dimensional thinking comes full circle.. Infect Immun 2003 Aug;71(8):4225-8.
- Mott J, Barnewall RE, Rikihisa Y. Human granulocytic ehrlichiosis agent and Ehrlichia chaffeensis reside in different cytoplasmic compartments in HL-60 cells.. Infect Immun 1999 Mar;67(3):1368-78.
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