Molecular Heterogeneity of
            <i>Ehrlichia chaffeensis</i>
            Isolates Determined by Sequence Analysis of the 28-Kilodalton Outer Membrane Protein Genes and Other Regions of the Genome

Cheng, Chuanmin; Paddock, Christopher D.; Ganta, Roman R.

doi:10.1128/iai.71.1.187-195.2003

Cited by 45 publications

(50 citation statements)

References 37 publications

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“…The three-and six-repeat types of the VLPT gene were the least common variants observed in this study; these variants have been found in infected humans on five occasions and one occasion, respectively. The three-repeat VLPT type has been found in humans only in Georgia, Tennessee, and Nebraska (1,12); however, in the present study this genetic variant was found in WTD from Kansas, thereby extending the geographic distribution of this genetic type. Similarly, the six-repeat VLPT profile has been found only once, in a human from Wakulla Co., Fla. (16).…”

contrasting

confidence: 52%

Molecular Variation in the Variable-Length PCR Target and 120-Kilodalton Antigen Genes ofEhrlichia chaffeensisfrom White-Tailed Deer (Odocoileus virginianus)

Yabsley

Little²,

Sims³

et al. 2003

J Clin Microbiol

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Genes encoding two surface-expressed antigens of Ehrlichia chaffeensis, the variable-length PCR target (VLPT) and the 120-kDa antigen, which contain variable numbers of tandem repeats, were characterized for E. chaffeensis from white-tailed deer (Odocoileus virginianus). Both genes from infected deer contained numbers of repeats similar to those reported in genes from humans and ticks, although a new variant of the 120-kDa antigen gene containing five repeat units and coinfection with multiple VLPT and 120-kDa antigen gene genetic types were detected. Sequence analysis of both genes revealed more nucleotide variation than previously reported for E. chaffeensis from infected humans or ticks. This is the most extensive study of E. chaffeensis VLPT and 120-kDa antigen gene genetic variation to date and is the first to examine genetic variation in E. chaffeensis from a nonhuman vertebrate host.

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contrasting

confidence: 52%

Molecular Variation in the Variable-Length PCR Target and 120-Kilodalton Antigen Genes ofEhrlichia chaffeensisfrom White-Tailed Deer (Odocoileus virginianus)

Yabsley

Little²,

Sims³

et al. 2003

J Clin Microbiol

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“…It was reported that transcripts of all the p28 omp genes were detected from an infected dog except for the p28-2 gene (22). However, other studies have detected transcripts for fewer p28 genes in cell culture (5,19,22). Differences in the detection of p28 omp gene transcripts by reverse transcription-PCR could be due to experimental variables, such as RNA template quantity and quality, or primer specificity.…”

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confidence: 76%

Expression of Members of the 28-Kilodalton Major Outer Membrane Protein Family ofEhrlichia chaffeensisduring Persistent Infection

et al. 2004

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The 28-kDa immunodominant outer membrane proteins (P28 OMPs) of Ehrlichia chaffeensis are encoded by a multigene family. As an indirect measure of the in vivo expression of the members of the p28 multigene family of E. chaffeensis, sera from two beagle dogs experimentally infected with E. chaffeensis were evaluated for the presence of specific antibodies to P28 OMPs by enzyme-linked immunosorbent assay. Antigenic peptides unique to each of the P28s were identified within the first hypervariable region of each P28 OMP. Serological responses to peptides derived from all P28 OMPs were detected from day 30 postinoculation to day 468 and from day 46 until day 159 in the two beagles. Although antibody titers to the peptides fluctuated, the peak response to all of the peptides appeared simultaneously in each dog. The antibody responses to another outer membrane protein of E. chaffeensis (GP120) showed similar temporal and quantitative changes. These data suggest that the P28 OMPs are expressed concurrently during persistent Ehrlichia infection.

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“…As the map1-2 gene is present in the Welgevonden and Senegal isolate and could also be amplified from other isolates (data not shown), we assume that the gene is deleted from CTVM Gardel. Cheng et al (9) showed that molecular heterogeneity of E. chaffeensis isolates occurred in the ␣-repetitive region of the cluster, giving rise to three genetic groups containing either 22 (group I and III) or 21 genes (group II). Two locations were identified where insertions and/or deletions occurred (9).…”

Section: Discussionmentioning

confidence: 99%

Transcription Analysis of the Major Antigenic Protein 1 Multigene Family of Three In Vitro-Cultured Ehrlichia ruminantium Isolates

et al. 2005

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Ehrlichia ruminantium, an obligate intracellular bacterium transmitted by ticks of the genus Amblyomma, causes heartwater disease in ruminants. The gene coding for the major antigenic protein MAP1 is part of a multigene family consisting of a cluster containing 16 paralogs. In the search for differentially regulated genes between E. ruminantium grown in endothelial and tick cell lines that could be used in vaccine development and to determine if differences in the map1 gene cluster exist between different isolates of E. ruminantium, we analyzed the map1 gene cluster of the Senegal and Gardel isolates of E. ruminantium. Both isolates contained the same number of genes, and the same organization as found in the genome sequence of the Welgevonden isolate (H. Van Heerden, N. E. Collins, K. A. Brayton, C. Rademeyer, and B. A. Allsopp, Gene 330:159-168, 2004). However, comparison of two subpopulations of the Gardel isolate maintained in different laboratories demonstrated that recombination between map1-3 and map1-2 had occurred in one subpopulation with deletion of one entire gene. Reverse transcription-PCR on E. ruminantium derived mRNA from infected cells using gene-specific primers revealed that all 16 map1 paralogs were transcribed in endothelial cells. In one vector (Amblyomma variegatum) and several nonvector tick cell lines infected with E. ruminantium, transcripts were found for between 4 and 11 paralogs. In all these cases the transcript for the map1-1 gene was detected and was predominant. Our results indicate that the map1 gene cluster is relatively conserved but can be subject to recombination, and differences in the transcription of map1 multigenes in host and vector cell environments exist.Ehrlichia ruminantium (formerly Cowdria ruminantium [12]) is the causative agent of heartwater, a rickettsial disease transmitted by ticks of the genus Amblyomma which causes major economic losses in wild and domestic ruminants. The disease is endemic in sub-Saharan Africa and also is present on some Caribbean islands (33), where it poses a risk of spreading to the American mainland. Feeding ticks transmit E. ruminantium to vertebrate hosts in their saliva and/or by gut regurgitation (8,19). Phylogenetic studies have revealed a close relationship between E. ruminantium, Ehrlichia canis, and Ehrlichia chaffeensis (30,39).In infections with these ehrlichial agents, the serological response is mainly directed against outer-membrane proteins of approximately 30 kDa. The genes coding for these proteins have been designated the major antigenic protein 1 (map1) in E. ruminantium (32,40), the outer membrane protein p28 (omp-1) in E. chaffeensis, and the p30 outer membrane protein (p30) in E. canis (27,28,30,35,36,42,43). The OMP-1 and P30 protein families are each encoded by a multigene family consisting of 22 genes arranged in a cluster between a hypothetical transcriptional regulator (upstream) and the secA gene (downstream). The 5Ј end of the cluster contains paralogs with short intergenic spaces, whereas the paralogs at t...

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Molecular Heterogeneity of Ehrlichia chaffeensis Isolates Determined by Sequence Analysis of the 28-Kilodalton Outer Membrane Protein Genes and Other Regions of the Genome

Cited by 45 publications

References 37 publications

Molecular Variation in the Variable-Length PCR Target and 120-Kilodalton Antigen Genes ofEhrlichia chaffeensisfrom White-Tailed Deer (Odocoileus virginianus)

Molecular Variation in the Variable-Length PCR Target and 120-Kilodalton Antigen Genes ofEhrlichia chaffeensisfrom White-Tailed Deer (Odocoileus virginianus)

Expression of Members of the 28-Kilodalton Major Outer Membrane Protein Family ofEhrlichia chaffeensisduring Persistent Infection

Transcription Analysis of the Major Antigenic Protein 1 Multigene Family of Three In Vitro-Cultured Ehrlichia ruminantium Isolates

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