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Khan A, Khanzada MH, Khan K, Jalal K, Uddin R. Integrating core subtractive proteomics and reverse vaccinology for multi-epitope vaccine design against Rickettsia prowazekii endemic typhus. Immunol Res 2024; 72:82-95. [PMID: 37608125 DOI: 10.1007/s12026-023-09415-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/13/2023] [Indexed: 08/24/2023]
Abstract
Rickettsia prowazekii is an intracellular, obligate, gram-negative coccobacillus responsible for epidemic typhus. Usually, the infected body louse or its excrement when rubbed into the skin abrasions transmits the disease. The infection with R. prowazekii causes the highest death rate (> 20% without antibiotic treatment and now 1-7%), followed by epidemic typhus, which often manifests in unsanitary conditions (up to 15-30%). Conventionally, vaccine design has required pathogen growth and both assays (in vivo and in vitro), which are costly and time-consuming. However, advancements in bioinformatics and computational biology have accelerated the development of effective vaccine designs, reducing the need for traditional, time-consuming laboratory experiments. Subtractive genomics and reverse vaccinology have become prominent computational methods for vaccine model construction. Therefore, the RefSeq sequence of Rickettsia prowazekii (strain Madrid E) (Proteome ID: UP000002480) was subjected to subtractive genomic analysis, including factors such as non-similarity to host proteome, essentiality, subcellular localization, antigenicity, non-allergenicity, and stability. Based on these parameters, the vaccine design process selected specific proteins such as outer membrane protein R (O05971_RICPR PETR; OmpR). Eventually, the OmpR was subjected to a reverse vaccinology approach that included molecular docking, immunological simulation, and the discovery of B-cell epitopes and MHC-I and MHC-II epitopes. Consequently, a chimeric or multi-epitope-based vaccine was proposed by selecting the V11 vaccine and its 3D structure modeling along with molecular docking against TLR and HLA protein, in silico simulation, and vector designing. The obtained results from this investigation resulted in a new perception of inhibitory ways against Rickettsia prowazekii by instigating novel immunogenic targets. To further assess the efficacy and protective ability of the newly designed V11 vaccine against Rickettsia prowazekii infections, additional evaluation such as in vitro or in vivo immunoassays is recommended.
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Affiliation(s)
- Ariba Khan
- Department of Biotechnology, University of Karachi, Karachi, Pakistan
- Lab 103, PCMD ext. Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Muhammad Hassan Khanzada
- Department of Biotechnology, University of Karachi, Karachi, Pakistan
- Lab 103, PCMD ext. Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Kanwal Khan
- Lab 103, PCMD ext. Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Khurshid Jalal
- HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Reaz Uddin
- Lab 103, PCMD ext. Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan.
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Alabbas AB. Identification of promising methionine aminopeptidase enzyme inhibitors: A combine study of comprehensive virtual screening and dynamics simulation study. Saudi Pharm J 2023; 31:101745. [PMID: 37638221 PMCID: PMC10448168 DOI: 10.1016/j.jsps.2023.101745] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 08/05/2023] [Indexed: 08/29/2023] Open
Abstract
Methionine aminopeptidase (MetAP) enzymes play a critical role in bacterial cell survival by cleaving formyl-methionine initiators at N-terminal of nascent protein, a process which is vital in proper protein folding. This makes MetAP an attractive and novel antibacterial target to unveil promising antibiotics. In this study, the crystal structure of R. prowazekii MetAP was used in structure-based virtual screening of drug libraries such as Asinex antibacterial library and Comprehensive Marine Natural Products Database (CMNPD) to identify promising lead molecules against the enzyme. This shortlisted three drug molecules; BDE-25098678, BDE-30686468 and BDD_25351157 as most potent leads that showed strong binding to the MetAP enzyme. The static docked conformation of the compounds to the MetAP was reevaluated in molecular dynamics simulation studies. The analysis observed the docked complexes as stable structure with no major local or global deviations noticed. These findings suggest the formation of strong intermolecular docked complexes, which showed stable dynamics and atomic level interactions network. The binding free energy analysis predicted net MMGBSA energy of complexes as: BDE-25098678 (-73.41 kcal/mol), BDE-30686468 (-59.93 kcal/mol), and BDD_25351157 (-75.39 kcal/mol). In case of MMPBSA, the complexes net binding energy was as; BDE-25098678 (-77.47 kcal/mol), BDE-30686468 (-69.47 kcal/mol), and BDD_25351157 (-75.6 kcal/mol). Further, the compounds were predicted to follow the famous Lipinski rule of five and have non-toxic, non-carcinogenic and non-mutagenic profile. The screened compounds might be used in experimental test to highlight the real anti- R. prowazekii MetAP activity.
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Affiliation(s)
- Alhumaidi B. Alabbas
- Department of Pharmaceutical Chemistry, College of Pharmacy, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
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Newton PN, Fournier PE, Tappe D, Richards AL. Renewed Risk for Epidemic Typhus Related to War and Massive Population Displacement, Ukraine. Emerg Infect Dis 2022; 28:2125-2126. [PMID: 36007931 PMCID: PMC9514335 DOI: 10.3201/eid2810.220776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Epidemic typhus, caused by Rickettsia prowazekii bacteria and transmitted through body lice (Pediculus humanus corporis), was a major public health threat in Eastern Europe as a consequence of World War II. In 2022, war and the resulting population displacement in Ukraine risks the return of this serious disease.
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Chekanova T, Shpynov S. Avidity of IgG to Rickettsia prowazekii and the presence of specific IgM in blood sera for retrospective analysis of the 1998 epidemic typhus outbreak in Russia. J Microbiol Methods 2020; 176:106034. [PMID: 32805367 DOI: 10.1016/j.mimet.2020.106034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/08/2020] [Accepted: 08/12/2020] [Indexed: 11/18/2022]
Abstract
The authors applied a new methodological approach based not only on the study of IgM/IgG to Rickettsia prowazekii in sera, but also on the estimation of the avidity index of specific IgG. The data allowed the authors to draw new conclusions about the 1998 epidemic typhus outbreak in Russia.
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Affiliation(s)
- Tatiana Chekanova
- Laboratory for Epidemiology of Natural Focal Infections, Central Research Institute of Epidemiology, 111123 Moscow, Russia.
| | - Stanislav Shpynov
- Omsk Research Institute of Natural Focal Infections, 644080 Omsk, Russia
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Cherry CC, Binder AM. Trends in clinical diagnoses of typhus group rickettsioses among a large U.S. insurance claims database. Zoonoses Public Health 2020; 67:291-299. [PMID: 31984654 DOI: 10.1111/zph.12687] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/23/2019] [Indexed: 01/03/2023]
Abstract
Typhus group rickettsioses (TGRs) are vector-borne diseases that include murine typhus (Rickettsia typhi) and epidemic typhus (R. prowazekii). Twentieth-century public health interventions led to dramatic decreases in incidence; little is known about the contemporary TGR prevalence because neither disease is nationally notifiable. We summarized administrative claims data in a commercially insured population to examine trends in TGR medical encounters. We analysed data from 2003 to 2016 IBM® MarketScan® Commercial Databases to identify persons with inpatient or outpatient visits with an International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification TGR-specific code. We summarized epidemiologic characteristics associated with incident diagnosis. We identified 1,799 patients diagnosed with a TGR. Patients resided in 46 states, and most were female (n = 1,019/1,799; 56.6%); the median age was 42 years (range: 0-64 years). Epidemic typhus (n = 931/1,799; 51.8%) was the most common TGRs, followed by murine typhus (n = 722/1,799; 40.1%). The majority of TGR patients were diagnosed in an outpatient setting (n = 1,725/1,799; 95.9%); among hospitalized patients, the majority received a murine typhus diagnosis (n = 67/74; 90.5%). TGRs are rarely diagnosed diseases. More patients were diagnosed with epidemic than murine typhus, even though R. prowazekii transmission requires body louse or flying squirrel exposure. Patients from all geographic regions were diagnosed with murine and epidemic typhus, despite historically recognized ranges for these diseases. The epidemiologic misalignment of insurance claims data versus historic TGRs data highlights the challenges of finding appropriate alternative data sources to serve as a proxy when national surveillance data do not exist.
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Affiliation(s)
- Cara C Cherry
- Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Alison M Binder
- Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
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Abstract
Rickettsia are small, obligately intracellular, gram-negative bacilli. They are distributed among a variety of hematophagous arthropod vectors and cause illness throughout the world. Rickettsioses present as an acute undifferentiated febrile illness and are often accompanied by headache, myalgias, and malaise. Cutaneous manifestations include rash and eschar, which both occur at varying incidence depending on the infecting species. Serology is the mainstay of diagnosis, and the indirect immunofluorescence assay is the test of choice. Reactive antibodies are seldom present during early illness, so testing should be performed on both acute-phase and convalescent-phase sera. Doxycycline is the treatment of choice.
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Affiliation(s)
- Lucas S Blanton
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0435, USA.
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Rauch J, Muntau B, Eggert P, Tappe D. Rickettsia typhi as Cause of Fatal Encephalitic Typhus in Hospitalized Patients, Hamburg, Germany, 1940-1944. Emerg Infect Dis 2019; 24:1982-1987. [PMID: 30334722 PMCID: PMC6200005 DOI: 10.3201/eid2411.171373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We evaluated formalin-fixed paraffin-embedded tissue specimens from 7 patients who died with encephalitic typhus in Hamburg, Germany, during World War II. The archived specimens included only central nervous system tissues >70 years old that had been stored at room temperature. We demonstrated successful detection of Rickettsia typhi DNA by a nested qPCR specific to prsA in 2 patients. These results indicate that R. typhi infections contributed to typhus outbreaks during World War II. Immunohistochemical analyses of brain tissue specimens of R. typhi DNA-positive and -negative specimens showed perivascular B-cell accumulation. Around blood vessels, nodular cell accumulations consisted of CD4-positive and CD8-positive T cells and CD68-positive microglia and macrophages; neutrophils were found rarely. These findings are similar to those of previously reported R. prowazekii tissue specimen testing. Because R. typhi and R. prowazekii infections can be clinically and histopathologically similar, molecular analyses should be performed to distinguish the 2 pathogens.
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Abstract
Typhus group rickettsiosis is caused by the vectorborne bacteria Rickettsia typhi and R. prowazekii. R. typhi, which causes murine typhus, the less severe endemic form of typhus, is transmitted by fleas; R. prowazekii, which causes the severe epidemic form of typhus, is transmitted by body lice. To examine the immunology of human infection with typhus group rickettsiae, we retrospectively reviewed clinical signs and symptoms, laboratory changes, and travel destinations of 28 patients who had typhus group rickettsiosis diagnosed by the German Reference Center for Tropical Pathogens, Hamburg, Germany, during 2010-2017. Immunofluorescence assays of follow-up serum samples indicated simultaneous seroconversion of IgM, IgA, and IgG or concurrence in the first serum sample. Cytokine levels peaked during the second week of infection, coinciding with organ dysfunction and seroconversion. For 3 patients, R. typhi was detected by species-specific nested quantitative PCR. For all 28 patients, R. typhi was the most likely causative pathogen.
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Ulutasdemir N, Eroglu F, Tanrıverdi M, Dagli EI, Koltas IS. The epidemic typhus and trench fever are risk for public health due to increased migration in southeast of Turkey. Acta Trop 2018; 178:115-118. [PMID: 29126839 DOI: 10.1016/j.actatropica.2017.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 10/11/2017] [Accepted: 11/03/2017] [Indexed: 11/28/2022]
Abstract
Pediculus humanus capitis is a small ectoparasitic insect that has lived and feds on human beings for thousands of years. Molecular techniques have been used for Pediculus species identification and evolutionary, phylogenic, and ecological studies. A total of 23 adults of P. h. capitis were collected in Gaziantep, located in southeast Turkey, and DNA was isolated from all P. h. capitis using DNA extraction kit. All DNA samples were screened for investigate of Ricettsia prowazekii, Bartonella quintana and Borrelia recurrentis with real-time polymerase chain reaction. In addition, we investigated genetic variation in DNA samples of Pediculus humanus capitis using the cytochrome oxidase I genetic DNA sequence. We found 4 (17.4%) Ricettsia prowazekii and 3 (13.1%) Bartonella quintana in DNA samples of Pediculus humanus capitis, while we did not find any Bartonella recurrentis in any of the DNA samples. We demonstrated 1.8% genetic variations in DNA samples of Pediculus humanus capitis with Bartonella quintana. The phylogenetic tree based on the cytochrome oxidase I gene revealed that P. h. capitis in southeast Turkey are classified into two clades (clade A, clade B) and Bartonella quintana was found in only clade B. However, we did not find any genetic variations in other DNA samples in this region. The genetic variations may be related to P. h.capitis vector of Bartonella quintana has found in this study. In addition, this study was shown that P. h. capitis do transmit Rickettsia prowazekii and Bartonella quintana to people, epidemic typhus and trench fever may emergence in Gaziantep southeast of Turkey in the future.
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Affiliation(s)
| | - Fadime Eroglu
- FaBiyosit Microbiology-Biotechnology R&D co., Adana, Turkey; Cukurova Universtiy, Biotechnology Department, Adana, Turkey.
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Schroeder CLC, Narra HP, Sahni A, Khanipov K, Patel J, Fofanov Y, Sahni SK. Transcriptional profiling of Rickettsia prowazekii coding and non-coding transcripts during in vitro host-pathogen and vector-pathogen interactions. Ticks Tick Borne Dis 2017; 8:827-836. [PMID: 28709615 DOI: 10.1016/j.ttbdis.2017.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/13/2017] [Accepted: 06/15/2017] [Indexed: 01/09/2023]
Abstract
Natural pathogen transmission of Rickettsia prowazekii, the etiologic agent of epidemic typhus, to humans is associated with arthropods, including human body lice, ticks, and ectoparasites of eastern flying squirrel. Recently, we have documented the presence of small RNAs in Rickettsia species and expression of R. prowazekii sRNAs during infection of cultured human microvascular endothelial cells (HMECs), which represent the primary target cells during human infections. Bacterial noncoding transcripts are now well established as critical post-transcriptional regulators of virulence and adaptation mechanisms in varying host environments. Despite their importance, little is known about the expression profile and regulatory activities of R. prowazekii sRNAs (Rp_sRs) in different host cells encountered as part of the natural life-cycle. To investigate the sRNA expression profile of R. prowazekii during infection of arthropod host cells, we employed an approach combining in vitro infection, bioinformatics, RNA sequencing, and PCR-based quantitation. Global analysis of R. prowazekii transcriptome by strand-specific RNA sequencing enabled us to identify 67 cis-acting (antisense) and 26 trans-acting (intergenic) Rp_sRs expressed during the infection of Amblyomma americanum (AAE2) cells. Comparative evaluation of expression during R. prowazekii infection of HMECs and AAE2 cells by quantitative RT-PCR demonstrated significantly higher expression of four selected Rp_sRs in tick AAE2 cells. Examination of the coding transcriptome revealed differential up-regulation of >150 rickettsial genes in either HMECs or AAE2 cells and yielded evidence for host cell-dependent utilization of alternative transcription start sites by 18 rickettsial genes. Our results thus suggest noticeable differences in the expression of both Rp_sRs as well as the coding transcriptome and the exploitation of multiple transcription initiation sites for select genes during the infection of human endothelium and tick vector cells as the host and yield new insights into rickettsial virulence and transmission mechanisms.
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Affiliation(s)
- Casey L C Schroeder
- Department of Pathology, University of Texas Medical Branch, 301 University Boulevard Galveston, TX 77555, USA.
| | - Hema P Narra
- Department of Pathology, University of Texas Medical Branch, 301 University Boulevard Galveston, TX 77555, USA.
| | - Abha Sahni
- Department of Pathology, University of Texas Medical Branch, 301 University Boulevard Galveston, TX 77555, USA.
| | - Kamil Khanipov
- Department of Pharmacology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
| | - Jignesh Patel
- Department of Pathology, University of Texas Medical Branch, 301 University Boulevard Galveston, TX 77555, USA.
| | - Yuriy Fofanov
- Department of Pharmacology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
| | - Sanjeev K Sahni
- Department of Pathology, University of Texas Medical Branch, 301 University Boulevard Galveston, TX 77555, USA.
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Helgren TR, Chen C, Wangtrakuldee P, Edwards TE, Staker BL, Abendroth J, Sankaran B, Housley NA, Myler PJ, Audia JP, Horn JR, Hagen TJ. Rickettsia prowazekii methionine aminopeptidase as a promising target for the development of antibacterial agents. Bioorg Med Chem 2016; 25:813-824. [PMID: 28089350 DOI: 10.1016/j.bmc.2016.11.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/06/2016] [Accepted: 11/08/2016] [Indexed: 01/07/2023]
Abstract
Methionine aminopeptidase (MetAP) is a class of ubiquitous enzymes essential for the survival of numerous bacterial species. These enzymes are responsible for the cleavage of N-terminal formyl-methionine initiators from nascent proteins to initiate post-translational modifications that are often essential to proper protein function. Thus, inhibition of MetAP activity has been implicated as a novel antibacterial target. We tested this idea in the present study by targeting the MetAP enzyme in the obligate intracellular pathogen Rickettsia prowazekii. We first identified potent RpMetAP inhibitory species by employing an in vitro enzymatic activity assay. The molecular docking program AutoDock was then utilized to compare published crystal structures of inhibited MetAP species to docked poses of RpMetAP. Based on these in silico and in vitro screens, a subset of 17 compounds was tested for inhibition of R. prowazekii growth in a pulmonary vascular endothelial cell (EC) culture infection model system. All compounds were tested over concentration ranges that were determined to be non-toxic to the ECs and 8 of the 17 compounds displayed substantial inhibition of R. prowazekii growth. These data highlight the therapeutic potential for inhibiting RpMetAP as a novel antimicrobial strategy and set the stage for future studies in pre-clinical animal models of infection.
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Affiliation(s)
- Travis R Helgren
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Congling Chen
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Phumvadee Wangtrakuldee
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Thomas E Edwards
- Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Bart L Staker
- Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Avenue N., Seattle, WA 98109, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Jan Abendroth
- Beryllium Discovery Corp., 7869 NE Day Road West, Bainbridge Island, WA 98110, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA
| | - Banumathi Sankaran
- Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Nicole A Housley
- Department of Microbiology and Immunology and The Center for Lung Biology, University of South Alabama College of Medicine, Laboratory of Infectious Diseases, 307 North University Blvd, Mobile, AL 36688, USA
| | - Peter J Myler
- Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Avenue N., Seattle, WA 98109, USA; Seattle Structural Genomics Center for Infectious Disease (SSGCID), Seattle, WA, USA; Department of Global Health and Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, WA 98195, USA
| | - Jonathon P Audia
- Department of Microbiology and Immunology and The Center for Lung Biology, University of South Alabama College of Medicine, Laboratory of Infectious Diseases, 307 North University Blvd, Mobile, AL 36688, USA
| | - James R Horn
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
| | - Timothy J Hagen
- Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA.
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Schroeder CLC, Narra HP, Sahni A, Rojas M, Khanipov K, Patel J, Shah R, Fofanov Y, Sahni SK. Identification and Characterization of Novel Small RNAs in Rickettsia prowazekii. Front Microbiol 2016; 7:859. [PMID: 27375581 PMCID: PMC4896933 DOI: 10.3389/fmicb.2016.00859] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 05/23/2016] [Indexed: 12/12/2022] Open
Abstract
Emerging evidence implicates a critically important role for bacterial small RNAs (sRNAs) as post-transcriptional regulators of physiology, metabolism, stress/adaptive responses, and virulence, but the roles of sRNAs in pathogenic Rickettsia species remain poorly understood. Here, we report on the identification of both novel and well-known bacterial sRNAs in Rickettsia prowazekii, known to cause epidemic typhus in humans. RNA sequencing of human microvascular endothelial cells (HMECs), the preferred targets during human rickettsioses, infected with R. prowazekii revealed the presence of 35 trans-acting and 23 cis-acting sRNAs, respectively. Of these, expression of two trans-acting (Rp_sR17 and Rp_sR60) and one cis-acting (Rp_sR47) novel sRNAs and four well-characterized bacterial sRNAs (RNaseP_bact_a, α-tmRNA, 4.5S RNA, 6S RNA) was further confirmed by Northern blot or RT-PCR analyses. The transcriptional start sites of five novel rickettsial sRNAs and 6S RNA were next determined using 5′ RLM-RACE yielding evidence for their independent biogenesis in R. prowazekii. Finally, computational approaches were employed to determine the secondary structures and potential mRNA targets of novel sRNAs. Together, these results establish the presence and expression of sRNAs in R. prowazekii during host cell infection and suggest potential functional roles for these important post-transcriptional regulators in rickettsial biology and pathogenesis.
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Affiliation(s)
- Casey L C Schroeder
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Hema P Narra
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Abha Sahni
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Mark Rojas
- Department of Pharmacology, University of Texas Medical Branch Galveston, TX, USA
| | - Kamil Khanipov
- Department of Pharmacology, University of Texas Medical Branch Galveston, TX, USA
| | - Jignesh Patel
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Riya Shah
- Department of Neuroscience, University of Texas at Dallas Dallas, TX, USA
| | - Yuriy Fofanov
- Department of Pharmacology, University of Texas Medical Branch Galveston, TX, USA
| | - Sanjeev K Sahni
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
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13
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Abstract
Epidemic typhus is an infectious disease caused by the bacterium Rickettsia prowazekii and transmitted by body lice (Pediculus humanus corporis). This disease occurs where conditions are crowded and unsanitary. This disease accompanied war, famine, and poverty for centuries. Historical and proxy climate data indicate that drought was a major factor in the development of typhus epidemics in Mexico during 1655–1918. Evidence was found for 22 large typhus epidemics in central Mexico, and tree-ring chronologies were used to reconstruct moisture levels over central Mexico for the past 500 years. Below-average tree growth, reconstructed drought, and low crop yields occurred during 19 of these 22 typhus epidemics. Historical documents describe how drought created large numbers of environmental refugees that fled the famine-stricken countryside for food relief in towns. These refugees often ended up in improvised shelters in which crowding encouraged conditions necessary for spread of typhus.
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