Antigenic relationships among the rickettsiae of the spotted fever and typhus groups

Vishwanath, Suryanarayanan

doi:10.1016/0378-1097(91)90238-6

Cited by 39 publications

(20 citation statements)

References 15 publications

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“…For each analysis, sequences were aligned using MUSCLE v3.6 [1], [2] (default parameters). Phylogenetic trees were estimated in PAUP* v4.0b10 (Altivec) under parsimony [7], implementing 500 random sequence additions with 100 trees saved per replication.…”

Section: Supporting Informationmentioning

confidence: 99%

“…For each analysis, sequences were aligned using MUSCLE v3.6 [1], [2] (default parameters). Alignments were not manually adjusted.…”

Section: Supporting Informationmentioning

confidence: 99%

“…Classically, the members of the genus Rickettsia have been divided into two groups: the tick-transmitted spotted fever group (SFG) and the insect-transmitted typhus group (TG) based on their antigenic and molecular profiles. However, these groups share some antigenic proteins such as outer membrane protein B (OmpB) and 17 kDa lipoprotein [2]. The tick-transmitted SFG currently includes over 16 species, several of which are known human pathogens ( R. rickettsii , R. conorii , and R. sibirica ).…”

Section: Introductionmentioning

confidence: 99%

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Surface Proteome Analysis and Characterization of Surface Cell Antigen (Sca) or Autotransporter Family of Rickettsia typhi

et al. 2012

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Surface proteins of the obligate intracellular bacterium Rickettsia typhi, the agent of murine or endemic typhus fever, comprise an important interface for host-pathogen interactions including adherence, invasion and survival in the host cytoplasm. In this report, we present analyses of the surface exposed proteins of R. typhi based on a suite of predictive algorithms complemented by experimental surface-labeling with thiol-cleavable sulfo-NHS-SS-biotin and identification of labeled peptides by LC MS/MS. Further, we focus on proteins belonging to the surface cell antigen (Sca) autotransporter (AT) family which are known to be involved in rickettsial infection of mammalian cells. Each species of Rickettsia has a different complement of sca genes in various states; R. typhi, has genes sca1 thru sca5. In silico analyses indicate divergence of the Sca paralogs across the four Rickettsia groups and concur with previous evidence of positive selection. Transcripts for each sca were detected during infection of L929 cells and four of the five Sca proteins were detected in the surface proteome analysis. We observed that each R. typhi Sca protein is expressed during in vitro infections and selected Sca proteins were expressed during in vivo infections. Using biotin-affinity pull down assays, negative staining electron microscopy, and flow cytometry, we demonstrate that the Sca proteins in R. typhi are localized to the surface of the bacteria. All Scas were detected during infection of L929 cells by immunogold electron microscopy. Immunofluorescence assays demonstrate that Scas 1–3 and 5 are expressed in the spleens of infected Sprague-Dawley rats and Scas 3, 4 and 5 are expressed in cat fleas (Ctenocephalides felis). Sca proteins may be crucial in the recognition and invasion of different host cell types. In short, continuous expression of all Scas may ensure that rickettsiae are primed i) to infect mammalian cells should the flea bite a host, ii) to remain infectious when extracellular and iii) to infect the flea midgut when ingested with a blood meal. Each Sca protein may be important for survival of R. typhi and the lack of host restricted expression may indicate a strategy of preparedness for infection of a new host.

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Section: Supporting Informationmentioning

confidence: 99%

“…For each analysis, sequences were aligned using MUSCLE v3.6 [1], [2] (default parameters). Alignments were not manually adjusted.…”

Section: Supporting Informationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface Proteome Analysis and Characterization of Surface Cell Antigen (Sca) or Autotransporter Family of Rickettsia typhi

et al. 2012

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“…They are divided into two groups, the typhus group (TG) and the spotted fever group (SFG), based on differences in the diseases that they cause and the presence of the outer membrane proteins, rOmpA and rOmpB (Vishwanath, 1991). Members of both groups are historically responsible for severe human diseases (Hackstadt, 1996) and are Category B and C Select Agents as defined by the National Institute of Allergy and Infectious Diseases (NIAID).…”

Section: Introductionmentioning

confidence: 99%

Rickettsial outer-membrane protein B (rOmpB) mediates bacterial invasion through Ku70 in an actin, c-Cbl, clathrin and caveolin 2-dependent manner

Chan

Cardwell

Hermanas

et al. 2009

Cellular Microbiology

143

209

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SummaryRickettsia conorii, an obligate intracellular tickborne pathogen and the causative agent of Mediterranean spotted fever, binds to and invades non-phagocytic mammalian cells. Previous work identified Ku70 as a mammalian receptor involved in the invasion process and identified the rickettsial autotransporter protein, rOmpB, as a ligand; however, little is known about the role of Ku70-rOmpB interactions in the bacterial invasion process. Using an Escherichia coli heterologous expression system, we show here that rOmpB mediates attachment to mammalian cells and entry in a Ku70-dependent process. A purified recombinant peptide corresponding to the rOmpB passenger domain interacts with Ku70 and serves as a competitive inhibitor of adherence. We observe that rOmpB-mediated infection culminates in actin recruitment at the bacterial foci, and that this entry process relies in part on actin polymerization likely imparted through protein tyrosine kinase and phosphoinositide 3-kinase-dependent activities and microtubule stability. Small-interfering RNA studies targeting components of the endocytic pathway reveal that entry by rOmpB is dependent on c-Cbl, clathrin and caveolin-2. Together, these results illustrate that rOmpB is sufficient to mediate Ku70-dependent invasion of mammalian cells and that clathrin-and caveolin-dependent endocytic events likely contribute to the internalization process.

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“…They are divided into 2 main groups: spotted fever group rickettsiae, including the agents of RMSF (R. rickettsii) and boutonneuse fever (R. conorii) among others, and typhus group rickettsiae, including the agents of louseborne epidemic typhus (R. prowazekii) and murine or endemic typhus (R. typhi) [1,8]. The spotted fever group rickettsiae differ from the typhus group rickettsiae in their capacity to stimulate host cell actin polymerization for cell-to-cell movement [24][25][26], a lipopolysaccharide that is specific for each group [27], and the presence of the rickettsial outer membrane protein A [28]. Although their genomes are closely related [15,16], there are differences that support the traditional view that the 2 groups are antigenically distinct [27,29].…”

Section: Discussionmentioning

confidence: 99%

T Cells Mediate Cross‐Protective Immunity between Spotted Fever Group Rickettsiae and Typhus Group Rickettsiae

Valbuena¹,

Jordan²,

Walker³

2004

J INFECT DIS

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Rickettsioses are severe infections caused by obligately intracellular bacteria that preferentially infect the endothelium lining the vasculature. The causative agents, rickettsiae, have been divided according to biological, genetic, and antigenic parameters into 2 main groups: spotted fever and typhus. They have not been thought to stimulate cross-reactive protective immune responses; however, in this study, we show that, in relevant animal models that mimic human rickettsial infections, there is reciprocal immunological cross-protection between spotted fever group and typhus group rickettsiae. Furthermore, we present evidence that T cells are responsible for this cross-immunity and that cross-stimulation of T cells also occurs in humans.

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Antigenic relationships among the rickettsiae of the spotted fever and typhus groups

Cited by 39 publications

References 15 publications

Surface Proteome Analysis and Characterization of Surface Cell Antigen (Sca) or Autotransporter Family of Rickettsia typhi

Surface Proteome Analysis and Characterization of Surface Cell Antigen (Sca) or Autotransporter Family of Rickettsia typhi

Rickettsial outer-membrane protein B (rOmpB) mediates bacterial invasion through Ku70 in an actin, c-Cbl, clathrin and caveolin 2-dependent manner

T Cells Mediate Cross‐Protective Immunity between Spotted Fever Group Rickettsiae and Typhus Group Rickettsiae

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