1) Immunomolecular analysis of protective Ehrlichia proteins, immunity, vaccines and diagnostics.
laboratory has contributed significantly to the immunomolecular
characterization of major immunoreactive proteins of agents associated
with human and veterinary monocytic ehrlichioses, including E.
chaffeensis and E. canis. Through these investigations, we have
identified and characterized many of the known antigens that strongly
reacted with antibody which included a group of tandem repeat proteins,
performed epitope mapping studies to demonstrate that antibodies
recognized species-specific linear and conformational epitopes, and
demonstrated that antibodies directed at these epitopes are protective.
These studies have provided a comprehensive group of antigens for
development of subunit vaccines and for species-specific molecular
immunodiagnostics for which I have extensive intellectual property and
licensing agreements with industry.
- a. Luo T, Patel JG,
Zhang XF, Walker DH and McBride JW. Immunoreactive protein repertoires
of Ehrlichia chaffeensis and E. canis reveal the dominance of
hypothetical proteins and conformation-dependent antibody epitopes.
Infect Immun, Oct 15;89(11):e0022421, doi: 10.1128/IAI.00224-21. Epub
2021 Aug 2. (Selected by the editors as an article of significant
- b. Luo T, Patel JG, Zhang XF, Walker DH,
and McBride JW. Ehrlichia chaffeensis and E. canis hypothetical protein
immunoanalysis reveals small secreted immunodominant proteins and
conformation-dependent antibody epitopes. npj Vaccines. 2020; 5:85.
- c. Velayutham
TS, Kumar S, Zhang XF, Kose N, Walker DH, Winslow G, Crowe JE, and
McBride JW. Ehrlichia chaffeensis outer membrane protein 1-specific
human antibody-mediated immunity is defined by intracellular
TRIM21-dependent innate immune activation and extracellular
neutralization. Infect. Immun. 2019 87: e00383-19. PMCID: PMC6867850.
(Selected by the editors as an article of significant
- d. Kuriakose J, Zhang XF, Luo T and McBride
JW. Molecular basis of antibody mediated immunity to Ehrlichia
chaffeensis involves species-specific linear epitopes in tandem repeat
proteins. Microbes Infect. 2012; 14:1054-63. PMCID: 3445803
Identification and functional analysis of Ehrlichia proteins.
has also identified and performed functional analysis of Ehrlichia
proteins that play a role in ehrlichial survival in the host cell.
Proteins such as disulfide bond formation protein (DsbA), ferric binding
protein (Fbp) and TRP120, the first ehrichial HECT-type ubiquitin
ligase effector. In these studies, we determined that the E. chaffeensis
Dsb functions consistent with E. coli Dsb. Our characterization of Fbp
revealed differences in iron acquision of Ehrlichia compared to other
gram-negative bacteria. We have recently determined the TRP120 effector
is a HECT ubiquitin ligase that primarily targets host cell nuclear
proteins for degradation to promote ehrlichial survival.
Zhu B, Das S, Mitra S, Farris TR, McBride JW. Ehrlichia chaffeensis
TRP120 moonlights as a HECT E3 ligase involved in self- and host
ubiquitination to influence protein interactions and stability for
intracellular survival. Infect. Immun. 2017 85:1-16 pii: e00290-17.
doi: 10.1128/IAI.00290-17 PMCID: PMC28630068.
- b. McBride JW, Ndip
L, Popov VL, Walker DH. Identification and functional analysis of an
immunoreactive DsbA-like thio-disulfide oxidoreductase of Ehrlichia spp.
Infect Immun. 2002; 70:2700-2703. PMCID: PMC127935
- c. Doyle CK,
Zhang X, Popov VL, McBride JW. An immunoreactive 38-kilodalton protein
of Ehrlichia canis shares structural homology and iron-binding capacity
with the ferric-ion binding protein family. Infect Immun. 2005; 73:62-69. PMCID: PMC538948
Identification of Ehrlichia effector proteins, secretion mechanisms and
molecular pathogen-host interactions.
My laboratory has concentrated
effort to understanding the prokaryote-eukaryote interface as we have
determined that many ehrlichial proteins we identified as major
immunoreactive proteins are secreted and contain tandem repeat and
ankyrin domains. We utilized yeast-two-hybrid assays to define molecular
protein-protein interactions with ehrlichial TRPs and reported the
first defined host protein targets of these ehrlichial effectors.
Further studies established that ehrlichial effectors interact with a
diverse array of host proteins associated with important cellular
processes. We have further determined that these host proteins have a
direct connection to ehrlichial intracellular survival. We have
determined that Ehrlichia TRP effectors are substrates of the type 1
secretion system, the first such description for an obligately
- a. Wakeel A, Kuriakose J,
and McBride JW. An Ehrlichia chaffeensis tandem repeat protein interacts
with multiple host targets involved in cell signaling, transcriptional
regulation and vesicle trafficking. Infect. Immun. 2009; 76:1572-1580.
(Selected by the editors as an article of significant
interest-“Spotlight” p.1721) PMCID: 2681728
- b. Luo T and McBride
JW. Ehrlichia chaffeensis TRP32 interacts with host cell targets that
influence intracellular survival. Infect. Immun. 2012; 80:2297-2306.
- c. Zhu B, Das S, Mitra S, Farris TR, McBride JW.
Ehrlichia chaffeensis TRP120 moonlights as a HECT E3 ligase involved in
self- and host ubiquitination to influence protein interactions and
stability for intracellular survival. Infect. Immun. 2017 85:1-16 pii:
e00290-17. doi: 10.1128/IAI.00290-17 PMCID: PMC5563569.
- d. Wakeel
A, den Dulk-Ras A, Hooykas PJJ, McBride JW. Ehrlichia chaffeensis
tandem repeat proteins are type 1 secretion system substrates related to
the repeats-in-toxin exoprotein family. Front. Cell. Infect. Microbio.
2011; 1:1-19. PMCID: PMC3417381
4) Ehrlichia-host DNA
interactions and host transcriptional regulation.
In addition to
effector-host interactions defined by our laboratory, we have also
determined that four ehrlichial effectors, TRP120, TRP32, TRP47 and
Ank200 are nucleomodulins that interact with host cell DNA. The TRP120
has a novel DNA binding domain defined by the tandem repeats that
directly binds DNA. We utilized ChIPSeq with next generation sequencing
to define target genes and DNA binding motifs of these effectors, and
are currently investigating mechanisms of nuclear trafficking, and
mechanisms of direct and indirect transcriptional regulation by TRPs.
Zhu B, Nethery KA, Kuriakose JA, Zhang, XF, and McBride JW. Nuclear
translocated Ehrlichia chaffeensis ankyrin repeat protein interacts with
the mid-A stretch of host promoter and intronic Alu elements. Infect
Immun 2009; 77:4243-4255. (Selected by the editors as an article of
significant interest-“Spotlight” p.4181) PMCID: PMC2747939
- b. Zhu
B, Kuriakose JA, Luo T, Ballesteros E, Gupta S, Fofanov Y, and McBride
JW. Ehrlichia chaffeensis TRP120 bind a G+C-rich motif in host cell DNA
and exhibits eukaryotic transcriptional activator function. Infect.
Immun. 2011; 79:4370-4381. PMCID: PMC3257946
- c. Mitra S, Dunphy
PS, Das S, Zhu B, Luo T, McBride JW. Ehrlichia chaffeensis TRP120
effector targets and recruits host polycomb group proteins for
degradation to promote intracellular infection. Infect. Immun.
86:e00845-17. PMCID: PMC29358333.
- d. Farris TR, Dunphy PS, Zhu B,
Kibler CE, and McBride JW. Ehrlichia chaffeensis TRP32 is a
nucleomodulin that directly regulates expression of host genes governing
differentiation and proliferation. Infect. Immun. 2016; 84:
3182-3194. Aug 29. pii: IAI.00657-16 (Selected by the editors as an
article of significant interest-“Spotlight” p.3093). PMCID: PMC5067751.
5) Ehrlichia exploitation of eukaryote pathways for
To further extend our understanding of how microbes seamlessly
interact with the eukaryotic host, we have more recently investigated
how multiple host proteins can interact with a single bacterial
effector. Post translational modifications extend the functional
properties of both eukaryote and prokaryote proteins, and thus, can
partially explain how a single effector protein can interact with
multiple eukaryote targets. Moreover, Ehrlichia have small genomes, so
PTMs may be particularly important for expansion of effector function
and interaction and modulation of eukaryote pathways. We identified the
first sumolyated bacterial protein/effector and determined its role in
protein-protein interactions. Current studies are further extending
these investigations to understand the full repertoire of ehrlichial
effector PTMs and their role in effector function in various cellular
contexts. We have shown that Ehrlichia activate host cellular
pathways (Wnt and Notch) using short liner motifs (SLiMs) to subvert
innate host defenses of the mononuclear phagocyte.
Wang JY, Zhu B, Patterson LL, Rogan MR, Kibler CE and McBride JW.
Ehrlichia chaffeensis TRP120 mediated ubiquitination and proteasomal
degradation of tumor suppressor FBW7 increases oncoprotein stability and
promotes infection. 2020; PLoS Pathogens 16: e1008541 PMCID:
- b. Luo T, Dunphy PS, Lina TT, McBride JW. Ehrlichia
chaffeensis exploits canonical and noncanonical host Wnt signaling
pathways to stimulate phagocytosis and promote intracellular survival.
Infect. Immun. 2016; 84:686-700. PMCID: PMC4771358 (Selected by the
editors as an article of significant interest-“Spotlight” p.611).
- c. Lina TT, Dunphy PS, Luo T, McBride JW. Ehrlichia chaffeensis TRP120 activates canonical
- Notch signaling to downregulate TLR2/4 expression and promote intracellular survival. mBio 2016; 7: e00672-16 PMCID: PMC4958247
Lina T, Lou T, Velayutham T, McBride JW. Ehrlichia activation of
Wnt-PI3K-mTOR signaling inhibits autolysosome generation and autophagic
destruction by the mononuclear phagocyte. Infect. Immun. 2017 Oct 9.
pii: IAI.00690-17. doi: 10.1128/IAI.00690-17. PMCID: PMC 5695117.