Publications by authors named "R Martin Roop"

92 Publications

Uncovering the Hidden Credentials of Virulence.

Microbiol Mol Biol Rev 2021 02 10;85(1). Epub 2021 Feb 10.

Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.

Bacteria in the genus are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.
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http://dx.doi.org/10.1128/MMBR.00021-19DOI Listing
February 2021

Characterizing the transport and utilization of the neurotransmitter GABA in the bacterial pathogen Brucella abortus.

PLoS One 2020 26;15(8):e0237371. Epub 2020 Aug 26.

Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia, United States of America.

The neurotransmitter gamma-aminobutyric acid (GABA) is the most abundant inhibitory neurotransmitter in the human brain; however, it is becoming more evident that this non-proteinogenic amino acid plays multiple physiological roles in biology. In the present study, the transport and function of GABA is studied in the highly infectious intracellular bacterium Brucella abortus. The data show that 3H-GABA is imported by B. abortus under nutrient limiting conditions and that the small RNAs AbcR1 and AbcR2 negatively regulate this transport. A specific transport system, gts, is responsible for the transport of GABA as determined by measuring 3H-GABA transport in isogenic deletion strains of known AbcR1/2 regulatory targets; however, this locus is unnecessary for Brucella infection in BALB/c mice. Similar assays revealed that 3H-GABA transport is uninhibited by the 20 standard proteinogenic amino acids, representing preference for the transport of 3H-GABA. Metabolic studies did not show any potential metabolic utilization of GABA by B. abortus as a carbon or nitrogen source, and RNA sequencing analysis revealed limited transcriptional differences between B. abortus 2308 with or without exposure to GABA. While this study provides evidence for GABA transport by B. abortus, questions remain as to why and when this transport is utilized during Brucella pathogenesis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237371PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449393PMC
October 2020

Effect Of Leaf Extract On Platelet Count In Chronic Immune Thrombocytopenic Purpura: A Case Series.

Integr Med (Encinitas) 2019 Oct;18(5):30-35

Kalispell Regional Medical Center, Kalispell, Montana, USA.

The leaves of have been used to treat thrombocytopenia in Dengue fever in areas where the virus is endemic. This case series describes the use of leaf liquid extract (CPLE) as an adjunctive therapy for four patients receiving standard-of-care treatment for chronic immune thrombocytopenic purpura (ITP). The cases presented here indicate that CPLE may prove beneficial in the management of chronic ITP for patients interested in alternative therapy before progressing to second-line treatments. A larger clinical trial is warranted to evaluate CPLE as an adjunctive therapy in chronic ITP.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7219447PMC
October 2019

The Cation Diffusion Facilitator Family Protein EmfA Confers Resistance to Manganese Toxicity in Brucella abortus 2308 and Is an Essential Virulence Determinant in Mice.

J Bacteriol 2019 12 6;202(1). Epub 2019 Dec 6.

Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA

The gene designated in the 2308 genome encodes an ortholog of the cation diffusion facilitator family protein EmfA which has been linked to resistance to Mn toxicity in A null mutant derived from strain 2308 displays increased sensitivity to elevated levels of Mn in the growth medium compared to that of the parent strain but wild-type resistance to Fe, Mg, Zn, Cu, Co, and Ni. Inductively coupled plasma mass spectroscopy also indicates that the mutant retains significantly higher levels of cellular Mn after exposure to this metal than the parent strain, which is consistent with the proposed role of EmfA as a Mn exporter. Phenotypic analysis of mutants indicates that EmfA plays a much more important role in maintaining Mn homeostasis and preventing the toxicity of this metal in than does the Mn-responsive transcriptional regulator Mur. EmfA is also an essential virulence determinant for 2308 in C57BL/6 and C57BL/6 mice, which suggests that avoiding Mn toxicity plays a critical role in pathogenesis. Mn nutrition is essential for the basic physiology and virulence of strains. The results of the study presented here demonstrate that the cation diffusion facilitator (CDF)-type metal exporter EmfA plays critical roles in maintaining Mn homeostasis and preventing Mn toxicity in and is an essential virulence determinant for these bacteria. EmfA and other cellular components involved in Mn homeostasis represent attractive targets for the development of improved vaccines and chemotherapeutic strategies for preventing and treating brucellosis in humans and animals.
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http://dx.doi.org/10.1128/JB.00357-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6932235PMC
December 2019

That's the Way You Do It.

Authors:
R Martin Roop

J Bacteriol 2019 Jun 22;201(12). Epub 2019 May 22.

Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.

About one-third of the proteins encoded by the bacterial genomes that have been sequenced to date are proteins of "unknown function." Studies aimed at defining the biological functions of these proteins represent an important frontier in prokaryotic biology. The study presented by J. Herrou et al. (J Bacteriol 201:e00134-19, 2019) in this issue of the provides an excellent example of how to pursue such studies and define a new virulence determinant for an important zoonotic pathogen.
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http://dx.doi.org/10.1128/JB.00216-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531615PMC
June 2019
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