Structure-Based Vaccines Provide Protection in a Mouse Model of Ehrlichiosis

Thomas, Sunil; Thirumalapura, Nagaraja; Crocquet‐Valdes, Patricia A.; Luxon, Bruce A.; Walker, David H.

doi:10.1371/journal.pone.0027981

Cited by 21 publications

(18 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Immunization of mice with recombinant P28, which is the E. chaffeensis major outer membrane β-barrel protein ( 27 ) and functions as a porin ( 61 ), protects mice from E. chaffeensis challenge ( 27 ). Furthermore, immunization of mice with Ehrlichia muris P28 confers protection from E. muris challenge ( 62 ). TRP120 is one of the proteins on the surface of isolated E. chaffeensis cells, the other two proteins being OmpA and VirB6-2, which are selectively degraded by E. chaffeensis HtrA protease upon treatment with the cell-permeable functional antagonist of cyclic-di-GMP; the E. chaffeensis transmembrane outer membrane proteins P28/Omp-1F, VirB9, and heat shock protein 60 (HSP60) were not degraded by the treatment in the same sample ( 63 ).…”

Section: Discussionmentioning

confidence: 99%

EtpE Binding to DNase X Induces Ehrlichial Entry via CD147 and hnRNP-K Recruitment, Followed by Mobilization of N-WASP and Actin

Kumar

Lin

Xiong

et al. 2015

mBio

View full text Add to dashboard Cite

Obligate intracellular bacteria, such as Ehrlichia chaffeensis, perish unless they can enter eukaryotic cells. E. chaffeensis is the etiological agent of human monocytic ehrlichiosis, an emerging infectious disease. To infect cells, Ehrlichia uses the C terminus of the outer membrane invasin entry-triggering protein (EtpE) of Ehrlichia (EtpE-C), which directly binds the mammalian cell surface glycosylphosphatidyl inositol-anchored protein, DNase X. How this binding drives Ehrlichia entry is unknown. Here, using affinity pulldown of host cell lysates with recombinant EtpE-C (rEtpE-C), we identified two new human proteins that interact with EtpE-C: CD147 and heterogeneous nuclear ribonucleoprotein K (hnRNP-K). The interaction of CD147 with rEtpE-C was validated by far-Western blotting and coimmunoprecipitation of native EtpE with endogenous CD147. CD147 was ubiquitous on the cell surface and also present around foci of rEtpE-C-coated-bead entry. Functional neutralization of surface-exposed CD147 with a specific antibody inhibited Ehrlichia internalization and infection but not binding. Downregulation of CD147 by short hairpin RNA (shRNA) impaired E. chaffeensis infection. Functional ablation of cytoplasmic hnRNP-K by a nanoscale intracellular antibody markedly attenuated bacterial entry and infection but not binding. EtpE-C also interacted with neuronal Wiskott-Aldrich syndrome protein (N-WASP), which is activated by hnRNP-K. Wiskostatin, which inhibits N-WASP activation, and cytochalasin D, which inhibits actin polymerization, inhibited Ehrlichia entry. Upon incubation with host cell lysate, EtpE-C but not an EtpE N-terminal fragment stimulated in vitro actin polymerization in an N-WASP- and DNase X-dependent manner. Time-lapse video images revealed N-WASP recruitment at EtpE-C-coated bead entry foci. Thus, EtpE-C binding to DNase X drives Ehrlichia entry by engaging CD147 and hnRNP-K and activating N-WASP-dependent actin polymerization.

show abstract

Section: Discussionmentioning

confidence: 99%

EtpE Binding to DNase X Induces Ehrlichial Entry via CD147 and hnRNP-K Recruitment, Followed by Mobilization of N-WASP and Actin

Kumar

Lin

Xiong

et al. 2015

mBio

View full text Add to dashboard Cite

show abstract

“…The 3D structure of IDO1 (Fig. B) was modeled using the online server for I‐TASSER (iterative threading assembly refinement) [Zhang et al, ; Zhang, ; Roy et al, ; Thomas et al, ]. Through these methods we chose a 20‐mer peptide sequence derived from murine IDO1 amino acids 60–79 (Genbank sequence NP_032350.1, designated muIDO1 60–79 as indicated by the red line in Fig.…”

Section: Methodsmentioning

confidence: 99%

Specific In Situ Detection of Murine Indoleamine 2, 3‐Dioxygenase

Thomas

DuHadaway

Prendergast

et al. 2013

J of Cellular Biochemistry

Self Cite

View full text Add to dashboard Cite

Indoleamine 2,3-dioxygenase-1 (IDO1) catabolizes the essential amino acid tryptophan, acting as a modifier of inflammation and immune tolerance. Recent work has implicated IDO1 in many human diseases, including in cancer, chronic infection, autoimmune disorders and neurodegenerative disease, stimulating a major surge in preclinical and clinical studies of its pathogenic functions. In the mouse, IDO1 is expressed widely but in situ detection of the enzyme in murine tissues has been unreliable due to the lack of specific antibodies that do not also react with tissues from animals that are genetically deficient in IDO1. Such probes are crucial to establish cellular mechanisms since IDO1 appears to act in different cell types depending on disease context, but reliable probes have been elusive in the field. In this report, we address this issue with the development of IDO1 monoclonal antibody 4B7 which specifically recognizes the murine enzyme in tissue sections, offering a reliable tool for immunohistology in preclinical disease models.

show abstract

“…Frequencies of Ehrlichia -specific IFN-γ-producing CD4+ T cells in the splenocyte population from separate groups of mice infected with E. muris were determined by flow cytometry as described previously [25;34]. …”

Section: Methodsmentioning

confidence: 99%

“…The protective role of antibodies directed against the E. chaffeensis P28-19 was demonstrated in SCID mice [23]. Recently, we demonstrated the protective roles of Ehrlichia heat-shock protein 60 and the OMPs: P28-9, P28-12, and P28-19 in the E. muris -C57BL/6 mouse model [24;25]. Furthermore, antibodies directed against the major epitopes in the TR regions of E. chaffeensis TRP120, TRP47 and TRP32 inhibit ehrlichial replication in vitro and reduce the bacterial burden in vivo .…”

Section: Introductionmentioning

confidence: 99%

Recombinant Ehrlichia P29 protein induces a protective immune response in a mouse model of ehrlichiosis

Thirumalapura

Crocquet‐Valdes

Saito

et al. 2013

Vaccine

Self Cite

View full text Add to dashboard Cite

Ehrlichioses are emerging tick-borne bacterial diseases of humans and animals for which no vaccines are available. The diseases are caused by obligately intracellular bacteria belonging to the genus Ehrlichia. Several immunoreactive proteins of ehrlichiae have been identified based on their reactivity with immune sera from human patients and animals. These include the major outer membrane proteins, ankyrin repeat proteins and tandem repeat proteins (TRP). Polyclonal antibodies directed against the tandem repeats (TRs) of Ehrlichia chaffeensis TRP32, TRP47 and TRP120 have been shown to provide protection in mice. In the present study, we evaluated E. muris P29, which is the ortholog of E. chaffeensis TRP47 and E. canis TRP36, as a subunit vaccine in a mouse model of ehrlichiosis. Our study indicated that unlike E. chaffeensis TRP47 and E. canis TRP36, orthologs of E. muris (P29) and E. muris-like agent (EMLA) do not contain tandem repeats. Immunization of mice with recombinant E. muris P29 induced significant protection against a challenge infection. The protection induced by E. muris P29 was associated with induction of strong antibody responses. In contrast to development of P29-specific IgG antibodies following immunization, development of P29-specific IgG antibodies, but not IgM antibodies, was impaired during persistent E. muris infection. Furthermore, our study indicated that CD4+ T cells target P29 during E. muris infection and differentiate into IFN-γ-producing Th1 effector/memory cells. In conclusion, our study indicated that orthologs of E. muris P29 showed considerable variation in the central tandem repeat region among different species, induction of P29-specific IgG antibody response was impaired during persistent E. muris infection, and rP29 induced protective immune responses.

show abstract

Structure-Based Vaccines Provide Protection in a Mouse Model of Ehrlichiosis

Cited by 21 publications

References 50 publications

EtpE Binding to DNase X Induces Ehrlichial Entry via CD147 and hnRNP-K Recruitment, Followed by Mobilization of N-WASP and Actin

EtpE Binding to DNase X Induces Ehrlichial Entry via CD147 and hnRNP-K Recruitment, Followed by Mobilization of N-WASP and Actin

Specific In Situ Detection of Murine Indoleamine 2, 3‐Dioxygenase

Recombinant Ehrlichia P29 protein induces a protective immune response in a mouse model of ehrlichiosis

Contact Info

Product

Resources

About