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Identification of 19 Polymorphic Major Outer Membrane Protein Genes and Their Immunogenic Peptides in Ehrlichia ewingii for Use in a Serodiagnostic Assay
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| Zeitschriftentitel: | Clinical and Vaccine Immunology |
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| Personen und Körperschaften: | , , , |
| In: | Clinical and Vaccine Immunology, 15, 2008, 3, S. 402-411 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Society for Microbiology
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| Schlagwörter: |
| Zusammenfassung: | <jats:title>ABSTRACT</jats:title> <jats:p> <jats:italic>Ehrlichia ewingii</jats:italic> , a tick-transmitted rickettsia previously known only as a canine pathogen, was recently recognized as a human pathogen. <jats:italic>E. ewingii</jats:italic> has yet to be cultivated, and there is no serologic test available to diagnose <jats:italic>E. ewingii</jats:italic> infection. Previously, a fragment (505 bp) of a single <jats:italic>E. ewingii</jats:italic> gene homologous to 1 of 22 genes encoding <jats:italic>Ehrlichia chaffeensis</jats:italic> immunodominant major outer membrane proteins 1 (OMP-1s)/P28s was identified. The purposes of the present study were to (i) determine the <jats:italic>E. ewingii omp-1</jats:italic> gene family, (ii) determine each OMP-1-specific peptide, and (iii) analyze all OMP-1 synthesized peptides for antigenicity. Using nested touchdown PCR and a primer walking strategy, we found 19 <jats:italic>omp-1</jats:italic> paralogs in <jats:italic>E. ewingii</jats:italic> . These genes are arranged in tandem downstream of <jats:italic>tr1</jats:italic> and upstream of <jats:italic>secA</jats:italic> in a 24-kb genomic region. Predicted molecular masses of the 19 mature <jats:italic>E. ewingii</jats:italic> OMP-1s range from 25.1 to 31.3 kDa, with isoelectric points of 5.03 to 9.80. Based on comparative sequence analyses among OMP-1s from <jats:italic>E. ewingii</jats:italic> and three other <jats:italic>Ehrlichia</jats:italic> spp., each <jats:italic>E. ewingii</jats:italic> OMP-1 oligopeptide that was predicted to be antigenic, bacterial surface exposed, unique in comparison to the other <jats:italic>E. ewingii</jats:italic> OMP-1s, and distinct from those of other <jats:italic>Ehrlichia</jats:italic> spp. was synthesized for use in an enzyme-linked immunosorbent assay. Plasmas from experimentally <jats:italic>E. ewingii</jats:italic> -infected dogs reacted significantly with most of the OMP-1-specific peptides, indicating that multiple OMP-1s were expressed and immunogenic in infected dogs. The results support the utility of the tailored OMP-1 peptides as <jats:italic>E. ewingii</jats:italic> serologic test antigens. </jats:p> |
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| Umfang: | 402-411 |
| ISSN: |
1556-6811
1556-679X |
| DOI: | 10.1128/cvi.00366-07 |