DNA restriction endonuclease cleavage pattern and protein antigen profile of Ehrlichia risticii

Dutta, S.; Shankarappa, Basavaraju; Thaker, Subhashchandra R.; Mattingly-Napier, Bonnie L.

doi:10.1016/0378-1135(90)90090-i

Cited by 14 publications

(13 citation statements)

References 16 publications

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“…Surface labeling with 125 I suggested that P50/SSA from N. risticii strain 25-D is a surface antigen (83). Furthermore, P50/SSA has been determined to be a protective antigen of N. risticii against homologous challenge; however, the length and number of repeats varied within SSAs of each strain, which is suggested to contribute to vaccine failure (15,82).…”

Section: Resultsmentioning

confidence: 99%

Analysis of complete genome sequence of Neorickettsia risticii: causative agent of Potomac horse fever

Lin

Zhang

Gibson

et al. 2009

Nucleic Acids Research

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Neorickettsia risticii is an obligate intracellular bacterium of the trematodes and mammals. Horses develop Potomac horse fever (PHF) when they ingest aquatic insects containing encysted N. risticii-infected trematodes. The complete genome sequence of N. risticii Illinois consists of a single circular chromosome of 879 977 bp and encodes 38 RNA species and 898 proteins. Although N. risticii has limited ability to synthesize amino acids and lacks many metabolic pathways, it is capable of making major vitamins, cofactors and nucleotides. Comparison with its closely related human pathogen N. sennetsu showed that 758 (88.2%) of protein-coding genes are conserved between N. risticii and N. sennetsu. Four-way comparison of genes among N. risticii and other Anaplasmataceae showed that most genes are either shared among Anaplasmataceae (525 orthologs that generally associated with housekeeping functions), or specific to each genome (>200 genes that are mostly hypothetical proteins). Genes potentially involved in the pathogenesis of N. risticii were identified, including those encoding putative outer membrane proteins, two-component systems and a type IV secretion system (T4SS). The bipolar localization of T4SS pilus protein VirB2 on the bacterial surface was demonstrated for the first time in obligate intracellular bacteria. These data provide insights toward genomic potential of N. risticii and intracellular parasitism, and facilitate our understanding of PHF pathogenesis.

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Section: Resultsmentioning

confidence: 99%

Analysis of complete genome sequence of Neorickettsia risticii: causative agent of Potomac horse fever

Lin

Zhang

Gibson

et al. 2009

Nucleic Acids Research

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“…Variation in antigenic proteins is a widespread and common characteristic of many bacteria, including E. risticii (8,12,13,41). For example, there are strains of E. risticii which have been described that differ in their antigenic components but exhibit identity at the 16S rRNA gene level (41).…”

Section: Discussionmentioning

confidence: 99%

“…Segments of two additional ehrlichia genes were amplified by PCR. Sets of nested primers were designed to detect portions of the E. risticii homolog of the Escherichia coli groESL heat shock operon (39) and the E. risticii 51-kDa major antigen gene (12,13,41). The following primer sequences were used to amplify the heat shock operon: 5Ј-ACCAGGCTACCTCACAGGC-3Ј and 5Ј-TTGACC CTCGCATCAATG-3Ј (outer primers); and 5Ј-CACAAGTTGGTTCAATTTC TGC-3Ј and 5Ј-CCGAGATCTTCAACAGTAAGGC-3Ј (inner primers).…”

Section: Snail Collectionmentioning

confidence: 99%

Detection ofEhrlichia risticii, the Agent of Potomac Horse Fever, in Freshwater Stream Snails (Pleuroceridae:Jugaspp.) from Northern California

Barlough¹,

Reubel²,

Madigan³

et al. 1998

Appl Environ Microbiol

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Ehrlichia DNA was identified by nested PCR in operculate snails (Pleuroceridae: Juga spp.) collected from stream water in a northern California pasture in which Potomac horse fever (PHF) is enzootic. Sequencing of PCR-amplified DNA from a suite of genes (the 16S rRNA, groESL heat shock operon, 51-kDa major antigen genes) indicated that the source organism closely resembledEhrlichia risticii, the causative agent of PHF. The minimum percentage of Juga spp. harboring the organism in the population studied was 3.5% (2 of 57 snails). No ehrlichia DNA was found in tissues of 123 lymnaeid, physid, and planorbid snails collected at the same site. These data suggest that pleurocerid stream snails may play a role in the life cycle of E. risticii in northern California.

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“…Southern blotting was done with the genomic DNA of both the strains and the probes made from the inserts of ZAP clones expressing the 85-, 55-, and 51-kDa antigens of the 90-12 strain by the previously described procedure (11). The DNA of each strain was extracted from the Renografinpurified organisms as described earlier (12). The probes were prepared by randomly labelling the inserts in the presence of [ 32 P]dCTP.…”

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confidence: 99%

Pathogenic, immunologic, and molecular differences between two Ehrlichia risticii strains

1995

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Ehrlichia risticii is the causative agent of Potomac horse fever (PHF), an acute infectious disease of horses. In the last few years, there have been several reports of PHF cases occurring even in vaccinated horses. We isolated a new strain of E. risticii (90-12 strain) from a vaccinated horse suffering from clinical PHF. The major pathogenic, immunologic, and molecular differences between the 90-12 strain and the 25-D strain, which was originally isolated during the outbreaks in 1984, were studied. The 90-12 strain was more pathogenic for mice and horses compared with the 25-D strain. In enzyme-linked immunosorbent assay and immunofluorescence assay with mouse and horse antisera of both the strains, two-to fourfold differences were observed between homologous and heterologous antigens. The differences in antigen profiles were demonstrated by Western blot (immunoblot) with mouse and horse antisera and also with the recombinant clone-specific antibodies. Though several antigens were similar in both the strains, there were significant differences between them in the 110-, 85-, 70-, 51-, and 33-kDa antigens. The 85-kDa antigen was present only in the 90-12 strain but cross-reacted with a 50-kDa antigen of the 25-D strain. The 51-kDa antigens of both strains had different migration patterns. Southern blot hybridization of the genome from both the strains with DNA probes made from the 51-, 55-, and 85-kDa recombinant clones of the 90-12 strain showed a similar pattern with probes of the 51-and 55-kDa clones for both the strains, whereas the probe of the 85-kDa clone showed a completely different pattern. The 16S rRNA gene sequences from the two strains were identical. Neither strain replicated in gamma interferontreated mouse peritoneal macrophages. In in vitro neutralization assay, sera from the 25-D strain-infected horse neutralized the homologous strain but did not neutralize the 90-12 strain, whereas sera from the 90-12 strain-infected horse neutralized both the strains. In mouse protection experiments, there was complete homologous protection. But in cross-protection, mice immunized with the 25-D strain were only partially protected against challenge with the 90-12 strain, whereas mice immunized with the 90-12 strain were completely protected against the 25-D strain challenge. These results clearly indicate that there are major differences between the 90-12 and 25-D strains which may have implications regarding the vaccine failure for PHF and the development of an efficient vaccine.

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DNA restriction endonuclease cleavage pattern and protein antigen profile of Ehrlichia risticii

Cited by 14 publications

References 16 publications

Analysis of complete genome sequence of Neorickettsia risticii: causative agent of Potomac horse fever

Analysis of complete genome sequence of Neorickettsia risticii: causative agent of Potomac horse fever

Detection ofEhrlichia risticii, the Agent of Potomac Horse Fever, in Freshwater Stream Snails (Pleuroceridae:Jugaspp.) from Northern California

Pathogenic, immunologic, and molecular differences between two Ehrlichia risticii strains

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