Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.3.3.1 (citrate synthase)
4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To confirm the phylogenetic analysis previously inferred by comparison of the citrate synthase and rOmpA gene sequences (gitA and ompA, respectively), the rOmpB gene (ompB) of 24 strains of the genus Rickettsia was amplified and sequenced. rOmpB is an outer-membrane protein of high molecular mass, the presence of which can be demonstrated in most rickettsiae by immunological cross-reactivity in Western blots. No PCR amplification was obtained with Rickettsia bellii or Rickettsia canadensis. For the other rickettsiae, phylogenetic analysis was inferred from the comparison of both the gene and derived protein sequences by using parsimony, maximum-likelihood and neighbour-joining methods which gave the same organization. All nodes were well supported (>86% bootstrap values), except in the cluster including Rickettsia africae strain S and Rickettsia parkeri, and this analysis confirmed the previously established phylogeny obtained from combining results from gltA and ompA. Based on phylogenetic data, the current classification of the genus Rickettsia is inappropriate, specifically its division into two groups, typhus and spotted fever. Integration of phenotypic, genotypic and phylogenetic data will contribute to the definition of a polyphasic taxonomy as has been done for other bacterial genera.
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PMID:Phylogenetic analysis of members of the genus Rickettsia using the gene encoding the outer-membrane protein rOmpB (ompB). 1093 49

In this report, placement of Rickettsia felis in the spotted fever group (SFG) rather than the typhus group (TG) of Rickettsia is proposed. The organism, which was first observed in cat fleas (Ctenocephalides felis) by electron microscopy, has not yet been reported to have been cultivated reproducibly, thereby limiting the standard rickettsial typing by serological means. To overcome this challenge, several genes were selected as targets to be utilized for the classification of R. felis. DNA from cat fleas naturally infected with R. felis was amplified by PCR utilizing primer sets specific for the 190 kDa surface antigen (rOmpA) and 17 kDa antigen genes. The entire 5,513 bp rompA gene was sequenced, characterized and found to have several unique features when compared to the rompA genes of other Rickettsia. Phylogenetic analysis of the partial sequence of the 17 kDa antigen gene indicated that R. felis is less divergent from the SFG rickettsiae than from the TG rickettsiae. The data corroborate results from previous reports that analysed the citrate synthase, 16S rRNA, rompB (135 kDa surface antigen), metK, ftsY, polA and dnaE genes that placed R. felis as a member of the SFG. The organism is passed trans-stadially and transovarially, and infection in the cat flea has been observed in the midgut, tracheal matrix, muscle, hypodermis, ovaries and testes.
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PMID:Rickettsia felis: molecular characterization of a new member of the spotted fever group. 1132 Oct 78

'Gene D' is the PS120-protein-encoding gene, first described in Rickettsia conorii and Rickettsia japonica. Sequence analysis of a 3030 bp fragment of 'gene D' in 24 representatives of the genus Rickettsia was carried out to complete phylogenetic analyses previously inferred by comparison of gene sequences encoding citrate synthase, 17 kDa antigen and rOmpA and rOmpB. The phylogenetic relationships between rickettsiae were inferred from the comparison of both the gene and the derived protein sequences, using the parsimony, neighbour-joining and maximum-likelihood methods. Five distinct groups of rickettsiae were identified. These were: the Rickettsia massiliae group, including R. massiliae, Bar 29, Rickettsia rhipicephali and Rickettsia aeschlimannii; the Rickettsia rickettsii group containing Rickettsia sibirica, 'Rickettsia mongolotimonae', Rickettsia parkeri, strain S, Rickettsia africae, the R. conorii complex, Rickettsia slovaca, Rickettsia honei, R. rickettsii, R. japonica and Rickettsia montanensis; the group currently containing only Rickettsia helvetica; the Rickettsia akari group including Rickettsia australis, R. akari and the ELB agent; Rickettsia prowazekii and Rickettsia typhi clustered in the typhus group. As significant bootstrap values were obtained for most of the nodes, sequence comparison of 'gene D' should be considered as a complementary approach in phylogenetic studies of rickettsiae.
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PMID:Phylogeny of Rickettsia spp. inferred by comparing sequences of 'gene D', which encodes an intracytoplasmic protein. 1149 33

A unique Rickettsia species (Rickettsia thailandii sp. nov.) was identified in an Ixodes granulatus by use of polymerase chain reaction heteroduplex mobility assay by use of segments of the citrate synthase gene. This tick was collected from Rattus rattus from Nakhon Ratchasima province in 1970. Another I. granulatus was infected with Thai tick typhus strain TT-118, Rickettsia honei sp. nov. Stenos, Roux, Walker & Raoult; this tick was removed from a R. rattus collected 4 years later from the same province. Ixodes granulatus is the first tick species in Australasia shown to be infected with R. honei and the unique Rickettsia species.
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PMID:Short report: Thai tick typhus, Rickettsia honei, and a unique rickettsia detected in Ixodes granulatus (Ixodidae: Acari) from Thailand. 1171 10

A highly specific real-time polymerase chain reaction (PCR) assay was developed to detect spotted fever and typhus group rickettsiae using the citrate synthase gene as the target. The assay amplified rickettsial members of the spotted fever and typhus group including Rickettsia akari, R. australis, R. conorii, R. honei, "R. marmionii," R. sibirica, R. rickettsii, R. typhi, and R. prowazekii. The ancestral group rickettsia, R. bellii, did not produce a positive reaction, nor did other members of the order Rickettsiales or any non-rickettsial bacteria. The assay had a sensitivity of one target copy number per reaction as determined by serial dilutions of a plasmid containing a spotted fever group target sequence. This quantitative assay is useful for the enumeration of rickettsiae in clinical specimens and the diagnosis of rickettsial illnesses, when rickettsial numbers are very low.
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PMID:A highly sensitive and specific real-time PCR assay for the detection of spotted fever and typhus group Rickettsiae. 1635 16

Classic murine typhus, caused by Rickettsia typhi, is endemic in the continental United States in areas of Texas and southern California. We conducted an environmental investigation in an urban area of Los Angeles identified as the probable exposure site for a case of murine typhus. Four Rattus norvegicus heavily infested with Xenopsylla cheopis (average 32.5 fleas per animal, range 20-42) were trapped, and fleas, blood, and tissues were collected. DNAs from all specimens were tested for R. typhi and Rickettsia felis using a TaqMan assay targeting the rickettsial citrate synthase gene. Although rickettsiemia was not detected, DNA of R. felis was detected in at least one tissue from each rat. Tissues from 3 rats were also positive for R. typhi DNA. R. typhi and R. felis DNAs were detected in fleas collected from each animal with average minimal infection rates of 10% and 32.3%, respectively. Although R. typhi still circulates in urban Los Angeles in the classic Oriental flea-rat cycle, R. felis is more prevalent, even in this association.
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PMID:Urban focus of Rickettsia typhi and Rickettsia felis in Los Angeles, California. 2114 68

Molecular diagnosis using real-time polymerase chain reaction (PCR) may allow earlier diagnosis of rickettsiosis. We developed a duplex real-time PCR that amplifies (1) DNA of any rickettsial species and (2) DNA of both typhus group rickettsia, that is, Rickettsia prowazekii and Rickettsia typhi. Primers and probes were selected to amplify a segment of the 16S rRNA gene of Rickettsia spp. for the pan-rickettsial PCR and the citrate synthase gene (gltA) for the typhus group rickettsia PCR. Analytical sensitivity was 10 copies of control plasmid DNA per reaction. No cross-amplification was observed when testing human DNA and 22 pathogens or skin commensals. Real-time PCR was applied to 16 clinical samples. Rickettsial DNA was detected in the skin biopsies of three patients. In one patient with severe murine typhus, the typhus group PCR was positive in a skin biopsy from a petechial lesion and seroconversion was later documented. The two other patients with negative typhus group PCR suffered from Mediterranean and African spotted fever, respectively; in both cases, skin biopsy was performed on the eschar. Our duplex real-time PCR showed a good analytical sensitivity and specificity, allowing early diagnosis of rickettsiosis among three patients, and recognition of typhus in one of them.
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PMID:Development of a duplex real-time PCR for the detection of Rickettsia spp. and typhus group rickettsia in clinical samples. 2209 2

A novel Rickettsia was detected in the rotund tick, Ixodes kingi Bishopp, 1911, based on comparative DNA sequence analyses of 4 genes; the rickettsial-specific 17-kDa antigen gene, citrate synthase gene (gltA), the outer surface membrane protein A gene (ompA), and the 16S rRNA gene. The rickettsiae in I. kingi differed in nucleotide sequence from those of other Rickettsia species by 5.8-18.3% for the 17-kDa gene, 0.9-13.9% for gltA, 5.5-22.8% for ompA, and 0.9-1.6% for the 16S rRNA gene. Phylogenetic analyses of the sequence data revealed that this putative new species of Rickettsia, provisionally named Candidatus Rickettsia kingi, does not belong to the spotted fever group or typhus group of rickettsiae, but represents a sister taxon to R. canadensis and Candidatus Rickettsia tarasevichiae. This novel Rickettsia was found in 60 of the 87 (69%) ticks examined, which included all feeding life cycle stages of I. kingi. Although adult I. kingi occasionally parasitize dogs and humans, it remains to be determined if this Rickettsia is pathogenic to these host species.
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PMID:Detection of a novel Rickettsia (Alphaproteobacteria: Rickettsiales) in rotund ticks (Ixodes kingi) from Saskatchewan, Canada. 2341 65

The flea-borne rickettsioses murine typhus (Rickettsia typhi) and flea-borne spotted fever (FBSF) (Rickettsia felis) are febrile diseases distributed among humans worldwide. Murine typhus has been known to be endemic to Kenya since the 1950s, but FBSF was only recently documented in northeastern (2010) and western (2012) Kenya. To characterize the potential exposure of humans in Kenya to flea-borne rickettsioses, a total of 330 fleas (134 pools) including 5 species (Xenopsylla cheopis, Ctenocephalides felis, Ctenocephalides canis, Pulex irritans, and Echidnophaga gallinacea) were collected from domestic and peridomestic animals and from human dwellings within Asembo, western Kenya. DNA was extracted from the 134 pooled flea samples and 89 (66.4%) pools tested positively for rickettsial DNA by 2 genus-specific quantitative real-time PCR (qPCR) assays based upon the citrate synthase (gltA) and 17-kD antigen genes and the Rfelis qPCR assay. Sequences from the 17-kD antigen gene, the outer membrane protein (omp)B, and 2 R. felis plasmid genes (pRF and pRFd) of 12 selected rickettsia-positive samples revealed a unique Rickettsia sp. (n=11) and R. felis (n=1). Depiction of the new rickettsia by multilocus sequence typing (MLST) targeting the 16S rRNA (rrs), 17-kD antigen gene, gltA, ompA, ompB, and surface cell antigen 4 (sca4), shows that it is most closely related to R. felis but genetically dissimilar enough to be considered a separate species provisionally named Candidatus Rickettsia asemboensis. Subsequently, 81 of the 134 (60.4%) flea pools tested positively for Candidatus Rickettsia asemboensis by a newly developed agent-specific qPCR assay, Rasemb. R. felis was identified in 9 of the 134 (6.7%) flea pools, and R. typhi the causative agent of murine typhus was not detected in any of 78 rickettsia-positive pools assessed using a species-specific qPCR assay, Rtyph. Two pools were found to contain both R. felis and Candidatus Rickettsia asemboensis DNA and 1 pool contained an agent, which is potentially new.
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PMID:Molecular detection of Rickettsia felis and Candidatus Rickettsia asemboensis in fleas from human habitats, Asembo, Kenya. 2367 18

A group of 14 persons who live in an area of Australia endemic for the Australian paralysis tick, Ixodes holocyclus, and who were involved in regularly collecting and handling these ticks, was examined for antibodies to tick-transmitted bacterial pathogens. Five (36%) had antibodies to Coxiella burnetii, the causative agent of Q fever and three (21%) had antibodies to spotted fever group (SFG) rickettsiae (Rickettsia spp). None had antibodies to Ehrlichia, Anaplasma, Orientia, or Borrelia (Lymedisease) suggesting that they had not been exposed to these bacteria. A total of 149 I. holocyclus ticks were examined for the citrate synthase (gltA) gene of the SFG rickettsiae and the com1 gene of C. burnetii; 23 (15.4%) ticks were positive for Rickettsia spp. and 8 (5.6%) positive for Coxiella spp. Sequencing of fragments of the gltA gene and the 17 kDa antigen gene from a selection of the ticks showed 99% and 100% homology, respectively, to Rickettsia australis, the bacterium causing Queenslandtick typhus. Thus, it appears that persons bitten by I. holocyclus in NE NSW, Australia have an approximate one in six risk of being infected with R. australis. Risks of Q fever were also high in this region but this may have been due to exposure by aerosol from the environment rather than by tick bite. A subset of 74 I. holocyclus ticks were further examined for DNA from Borrelia spp., Anaplasma spp. and Ehrlichia spp. but none was positive. Some of these recognised human bacterial pathogens associated with ticks may not be present in this Australian tick species from northeastern New South Wales.
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PMID:Ixodes holocyclus Tick-Transmitted Human Pathogens in North-Eastern New South Wales, Australia. 3027 Aug 55


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