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217 results on '"Bouyer, Donald H."'

2. Spotted Fever and Typhus Group Rickettsiae in Dogs and Humans, Mexico, 2022

Author

Palacios-Santana, Ricardo, Wei, Lihua, Fernandez-Santos, Nadia A., Rodriguez- Perez, Mario A., Uriegas-Camargo, Sergio, Mendell, Nicole L., Bouyer, Donald H., and Estrada-Franco, Jose Guillermo

Subjects
Reynosa, Mexico -- Health aspects, Dogs -- Health aspects, Disease transmission -- Risk factors, Rickettsia -- Identification and classification -- Distribution, Rickettsial diseases -- Risk factors, Company distribution practices, Health
Abstract

The spotted fever group (SFG) rickettsiae, which are transmitted primarily by tick bite to rodents, dogs, wild animals, and persons, comprise a phylogenetically discrete clade of the family Rickettsiacae, encompassing [...]

Published
2023
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3. Whole-Genome Sequence of Rickettsia parkeri Strain Atlantic Rainforest, Isolated from a Colombian Tick

Author

Londoño, Andrés F, Mendell, Nicole L, Valbuena, Gustavo A, Routh, Andrew L, Wood, Thomas G, Widen, Steven G, Rodas, Juan D, Walker, David H, and Bouyer, Donald H

Subjects
Microbiology, Biological Sciences, Genetics, Vector-Borne Diseases, Biochemistry and Cell Biology
Abstract

Rickettsia parkeri is classified as a member of the alphaproteobacterial microorganisms, genus Rickettsia Here, we report the complete genome sequence of Rickettsia parkeri strain Atlantic Rainforest, which was isolated from an Amblyomma ovale tick collected in the municipality of Necoclí, Colombia.

Published
2019

7. Exchange protein directly activated by cAMP plays a critical role in bacterial invasion during fatal rickettsioses

Author

Gong, Bin, Shelite, Thomas, Mei, Fang C, Ha, Tuha, Hu, Yaohua, Xu, Guang, Chang, Qing, Wakamiya, Maki, Ksiazek, Thomas G, Boor, Paul J, Bouyer, Donald H, Popov, Vsevolod L, Chen, Ju, Walker, David H, and Cheng, Xiaodong

Subjects
Biodefense, Emerging Infectious Diseases, Infectious Diseases, Vaccine Related, Prevention, Rare Diseases, Vector-Borne Diseases, Aetiology, 2.1 Biological and endogenous factors, Infection, Good Health and Well Being, Animals, Bacterial Adhesion, Guanine Nucleotide Exchange Factors, Host-Pathogen Interactions, Human Umbilical Vein Endothelial Cells, Humans, Hydrazones, Immunohistochemistry, Isoxazoles, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Rickettsia Infections, Signal Transduction, rickettsial infection, cyclic AMP, Epac inhibitor, therapeutics, prophylaxis
Abstract

Rickettsiae are responsible for some of the most devastating human infections. A high infectivity and severe illness after inhalation make some rickettsiae bioterrorism threats. We report that deletion of the exchange protein directly activated by cAMP (Epac) gene, Epac1, in mice protects them from an ordinarily lethal dose of rickettsiae. Inhibition of Epac1 suppresses bacterial adhesion and invasion. Most importantly, pharmacological inhibition of Epac1 in vivo using an Epac-specific small-molecule inhibitor, ESI-09, completely recapitulates the Epac1 knockout phenotype. ESI-09 treatment dramatically decreases the morbidity and mortality associated with fatal spotted fever rickettsiosis. Our results demonstrate that Epac1-mediated signaling represents a mechanism for host-pathogen interactions and that Epac1 is a potential target for the prevention and treatment of fatal rickettsioses.

Published
2013

14. Reemergence of murine typhus in Galveston, Texas, USA, 2013

Author

Blanton, Lucas S., Vohra, Rahat F., Bouyer, Donald H., and Walker, David H.

Subjects
Typhus -- Diagnosis -- Causes of -- Distribution -- Genetic aspects -- Care and treatment -- Research, Disease transmission -- Control, Company distribution practices, Health
Abstract

Murine typhus, caused by Rickettsia typhi, is typically transmitted to humans by Xenopsylla cheopis, a flea that infests rats. The disease is endemic to tropical and subtropical seaboard regions throughout [...]

Published
2015
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17. Acute spotted fever rickettsiosis among febrile patients, Cameroon

Author

Ndip, Lucy M., Bouyer, Donald H., Da Rosa, Amelia P.A. Travassos, Titanji, V.P.K., Tesh, Robert B., and Walker, David H.

Subjects
Rickettsia -- Research
Abstract

Although potential arthropod vectors are abundant in Cameroon, acute febrile illnesses are rarely evaluated for arboviral or rickettsial infections. Serum samples from 234 acutely febrile patients at clinics in Tiko [...]

Published
2004

18. Polarized lung inflammation and Tie2/angiopoietin-mediated endothelial dysfunction during severe Orientia tsutsugamushi infection

Author

Trent, Brandon, primary, Liang, Yuejin, additional, Xing, Yan, additional, Esqueda, Marisol, additional, Wei, Yang, additional, Cho, Nam-Hyuk, additional, Kim, Hong-Il, additional, Kim, Yeon-Sook, additional, Shelite, Thomas R., additional, Cai, Jiyang, additional, Sun, Jiaren, additional, Bouyer, Donald H., additional, Liu, Jinjun, additional, and Soong, Lynn, additional

Published
2020
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19. Detection of Rickettsiae, Borreliae, and Ehrlichiae in Ticks Collected from Walker County, Texas, 2017–2018

Author

Mendell, Nicole L., primary, Reynolds, Erin S., additional, Blanton, Lucas S., additional, Hermance, Meghan E., additional, Londoño, Andres F., additional, Hart, Charles E., additional, Quade, Bethany R., additional, Esterly, Allen T., additional, Hendrix, C’Brionne B., additional, Teel, Pete D., additional, Bouyer, Donald H., additional, and Thangamani, Saravanan, additional

Published
2019
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21. Polarized Lung Inflammation and Tie2/Angiopoietin-Mediated Endothelial Dysfunction during Severe Orientia tsutsugamushi Infection

Author

Trent, Brandon, primary, Liang, Yuejin, additional, Xing, Yan, additional, Esqueda, Marisol, additional, Wei, Yang, additional, Cho, Nam-Hyuk, additional, Kim, Hong-Il, additional, Kim, Yeon-Sook, additional, Shelite, Thomas R., additional, Cai, Jiyang, additional, Sun, Jiaren, additional, Bouyer, Donald H., additional, Liu, Jinjun, additional, and Soong, Lynn, additional

Published
2019
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25. Amblyomma imitator ticks as vectors of Rickettsia rickettsii, Mexico

Author

Oliveira, Karla A., Pinter, Adriano, Medina-Sanchez, Aaron, Boppana, Venkata D., Wikel, Stephen K., Saito, Tais B., Popov, Vsevolod, Teel, Pete D., Walker, David H., Galvao, Marcio A.M., Mafra, Claudio, and Bouyer, Donald H.

Subjects
Rickettsia -- Health aspects -- Research -- Usage, Polymerase chain reaction -- Usage -- Health aspects -- Research, Health
Abstract

Rickettsia rickettsii is a gram-negative, obligate, intracellular bacterium and the cause of Rocky Mountain spotted fever (RMSF). In Mexico, its transmission has been attributed to Rhipicephalus sanguineus and Amblyomma cajennense [...]

Published
2010
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30. Type 1-skewed neuroinflammation and vascular damage associated with Orientia tsutsugamushi infection in mice

Author

Soong, Lynn, primary, Shelite, Thomas R., additional, Xing, Yan, additional, Kodakandla, Harica, additional, Liang, Yuejin, additional, Trent, Brandon J., additional, Horton, Paulina, additional, Smith, Kathryn C., additional, Zhao, Zhenyang, additional, Sun, Jiaren, additional, Bouyer, Donald H., additional, and Cai, Jiyang, additional

Published
2017
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34. An Intradermal Inoculation Mouse Model for Immunological Investigations of Acute Scrub Typhus and Persistent Infection

Author

Soong, Lynn, primary, Mendell, Nicole L., additional, Olano, Juan P., additional, Rockx-Brouwer, Dedeke, additional, Xu, Guang, additional, Goez-Rivillas, Yenny, additional, Drom, Claire, additional, Shelite, Thomas R., additional, Valbuena, Gustavo, additional, Walker, David H., additional, and Bouyer, Donald H., additional

Published
2016
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36. Quantitative study of Rickettsia massiliae in Rhipicephalus sanguineus organs

Author

Vilhena, Maria Manuela Clemente, Milhano, Natacha, Popov, Vsevolod, Jost, Cristine, de Sousa, Rita, Walker, David H., and Bouyer, Donald H.

Subjects
PARASITOLOGY, TICKS
Abstract

Rickettsia massiliae, belonging to the spotted fever group of Rickettsia, is a human pathogen causing a similar course of disease to that caused by R. conorii, the originally recognized etiologic agent of Mediterranean spotted fever. In view of this similarity, we performed an ultrastructural study of R. massiliae in organs of Rhipicephalus sanguineus ticks, in order to advance knowledge of the complex dynamics at the tick-pathogen interface in rickettsioses. Adult R. massiliae-infected Rh. sanguineus ticks were fed on uninfected Hartley strain guinea pigs, and five females were collected daily throughout their feeding period up to day 6, and analyzed by quantitative real-time PCR and electron microscopy. An increase in rickettsial content was observed in the salivary glands, particularly in the first two days of feeding, and a plateau was observed between days 3 and 6. Rickettsial organisms were observed in all tick organs analyzed, in higher numbers in the fed state, and statistically significant differences were observed in measurements of the periplasmic layer of R. massiliae in salivary glands of fed and unfed Rh. sanguineus ticks, with increased thickness in the former case. This study provides insight into the interface between R. massiliae and Rh. sanguineus ticks, highlighting the need for analysis of R. massiliae to fully ascertain its place as an important pathogenic agent of a spotted fever rickettsiosis.

Published
2014

44. Comparative OmpA gene analysis of Rickettsia felis-like bacteria detected in Haemaphysalis sulcata ticks and isolated in mosquito C6/36 cell line

Author

Duh, Darja, Avšič-Županc, Tatjana, Punda-Polić, Volga, Dolinšek, Jan, Gračner, Maja, Castro-Zavala, Jorge E, Bouyer, Donald H, Walker, David H, Bradarić, Nikola, Raoult, Didier, and Brouqui, philippe

Subjects
bacteria, Rickettsiae, OmpA gene, Haemaphsalis sulcata, bacterial infections and mycoses
Abstract

Objectives: The immunodominant OmpA protein of SFG Rickettsia plays a role in cell invasion and contains a domain of different number of tandem repeats, which dictates the genetic diversity of SFG Rickettsia. This protein is therefore used for the diagnosis of rickettsioses, species characterization and is considered as a potential vaccine candidate. The focus of our present study is the molecular characterization of the ompA gene amplified from a Rickettsia felis-like bacterium previously detected in Haemaphysalis sulcata ticks and from the same bacterium grown in mosquito C6/36 cells. Methods: DNA was extracted from 4 H. sulcata ticks and from the third passage of the isolate. Amplicons of complete ompA were obtained with two PCRs producing overlapping fragments named A and B. Primer sets were designed based on the alignment of rickettsial ompA sequences and using genome walking. Distinctive ompA amplicons were also cloned. In addition, RNA was extracted from stored halves of the ticks. It was transcribed and amplified by one step RT-PCR. Seven A and B amplicons were sequenced. Eighteen primers were needed to sequence fragment A. Sequencing of fragment B, which contains tandem repeats, is in process. Sequences were assembled, aligned and examined for sequence similarity. The phylogenetic trees were drawn with Treecon. Results: The ompA gene was successfully amplified from both H. sulcata ticks and from the bacteria isolated and cultured in C6/36 cells. Amplified fragments A and B were approximately 3000 and 4000 bp long, respectively. Fragment A sequences were compared between those obtained (i) directly from tick DNA and from the respective clone ; (ii) directly from tick DNA and from the isolate ; (iii) directly from tick DNA, but ticks were collected in different locations. Two, 16 and 45 nucleotide changes were noted in first, second and third sources of DNA, respectively. Changes in all samples were point mutations with the exception of insertions seen only in the second DNA source. RT-PCR of complete ompA resulted in an approximately 6500 bp long product. Phylogenetic analysis of Rickettsia felis-like bacteria based on partial ompA showed a maximum of 90.9 % identity with other SFG Rickettsia. Conclusions: Results of analysis of ompA sequences from fragment A demonstrated the presence of a unique species of Rickettsia. Given the substantial genetic divergence of the new Rickettsia, establishment of the isolate in C6/36 cells and TEM evidence of Rickettsia in internal organs of infected ticks, we propose the name of a new SFG species Rickettsia croatica, strain Kastelanii.

Published
2008

45. CD8+ T cells provide immune protection against murine disseminated endotheliotropic Orientia tsutsugamushi infection.

Author

Xu, Guang, Mendell, Nicole L., Liang, Yuejin, Shelite, Thomas R., Goez-Rivillas, Yenny, Soong, Lynn, Bouyer, Donald H., and Walker, David H.

Subjects
T cells, SCURFIN (Protein), LYMPHOCYTES, TSUTSUGAMUSHI disease, MESSENGER RNA
Abstract

Scrub typhus, caused by a Gram-negative obligately intracellular coccobacillus, Orientia tsutsugamushi, is a long neglected but important tropical disease. Orientia tsutsugamushi causes illness in one million people each year, and 1 billion people are at risk. Without appropriate diagnosis and treatment, the disease can cause severe multiorgan failure with a case fatality rate of 7–15%. The current gaps in knowledge of immunity include the unknown mechanisms of host immunity to O. tsutsugamushi. Using an intravenous (i.v.) disseminated infection mouse model, we observed that more CD8+ T cells than CD4+ T cells were present in the spleen of infected mice at 12 dpi. We also determined that Treg cells and the proportion of T cells producing IL-10 were significantly increased from 6 dpi, which correlated with the onset of illness, body weight loss, and increased bacterial loads. We further studied CD8-/-, MHC I-/- and wild type control (WT) C57BL/6J mice to determine the importance of CD8+ T cells and MHC I molecules. After infection with an ordinarily sub-lethal dose of O. tsutsugamushi, all CD8-/- and MHC I-/- mice were moribund between 12 and 15 dpi, whereas all WT mice survived. Bacterial loads in the lung, kidney, liver and spleen of CD8-/- and MHC I-/- mice were significantly greater than those in WT mice. Interferon-γ (IFN-γ) and granzyme B mRNA levels in the liver of CD8-/- and MHC I-/- mice were significantly greater than in WT mice. In addition, more severe histopathologic lesions were observed in CD8-/- mice. Finally, adoptive transfer confirmed a major role of immune CD8+ T cells as well as a less effective contribution by immune CD8 T cell-depleted splenocytes in protection against O. tsutsugamushi infection. These studies demonstrated the critical importance of CD8+ T cells in the host immune response during O. tsutsugamushi infection. [ABSTRACT FROM AUTHOR]

Published
2017
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