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F Jongejan - One of the best experts on this subject based on the ideXlab platform.
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amblyomma hebraeum is the predominant tick species on goats in the mnisi community area of mpumalanga province south africa and is co infected with ehrlichia ruminantium and rickettsia africae
Parasites & Vectors, 2020Co-Authors: F Jongejan, Laura Berger, Suzanne Busser, Iris Deetman, Manon Jochems, Tiffany Leenders, Barry De Sitter, Francine Van Der Steen, Jeanette WentzelAbstract:In sub-Saharan Africa, Amblyomma ticks are vectors of Heartwater Disease in domestic ruminants, caused by the rickettsial pathogen Ehrlichia ruminantium. Immature tick stages often bite humans, whereby they act as vectors of tick-bite fever caused by Rickettsia africae. Moreover, Amblyomma ticks cause damage to livestock due to their feeding behaviour. In South Africa, we studied the abundance of Amblyomma hebraeum ticks on goats of emerging farmers in Mpumalanga Province. A selected number of A. hebraeum nymphs and adult ticks was tested for co-infection with E. ruminantium and R. africae. A total of 630 indigenous goats, belonging to farmers in the Mnisi Community area, were examined for ticks in 2013 and 2014. All ticks were identified, and a selected number was tested by PCR with reverse line blot hybridisation. In total, 13,132 ticks were collected from goats distributed over 17 different households. Amblyomma hebraeum was the predominant species, followed by R. microplus. Rhipicephalus appendiculatus, R. simus and R. zambeziensis were also identified. Amblyomma hebraeum was present throughout the year, with peak activity of adults in summer (November) and nymphs in winter (July). The ratio between adults and nymphs ranged from 1:2.7 in summer to 1:55.1 in winter. The mean prevalence of infection for E. ruminantium by PCR/RLB in adult ticks was 17.4% (31/178), whereas 15.7% (28/178) were infected with R. africae. In pooled nymphs, 28.4% were infected with E. ruminantium and 38.8% carried R. africae infection. Co-infections of E. ruminantium and R. africae in adult and pooled nymphal ticks were 3.9% (7/178) and 10% (14.9), respectively. Lameness of goats due to predilection of ticks for the interdigital space of their feet was observed in 89% of the households. Goats act as important alternative hosts for cattle ticks, which underscored the necessity to include goats in control programs. It is suggested to use acaricide-impregnated leg-bands as a sustainable method to kill ticks and prevent lameness in goats. The challenge of goats by considerable numbers of E. ruminantium-infected ticks is a major obstacle for upgrading the indigenous goat breeds. Humans may be at risk to contract tick-bite fever in this area.
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Molecular detection of Ehrlichia ruminantium infection in Amblyomma variegatum ticks in The Gambia
Experimental and Applied Acarology, 2007Co-Authors: B. Faburay, M Postigo, A Taoufik, Susanne Munstermann, D. Geysen, F JongejanAbstract:In West Africa, losses due to Heartwater Disease are not known because the incidence/prevalence has not been well studied or documented. To develop a diagnostic tool for molecular epidemiology, three PCR-based diagnostic assays, a nested pCS20 PCR, a nested map 1 PCR and a nested reverse line blot (RLB) hybridization assay, were evaluated to determine their ability to detect infection in vector ticks, by applying them simultaneously to A. variegatum field ticks to detect Ehrlichia ruminantium , the causative agent of Heartwater. The nested pCS20 PCR assay which amplified the pCS20 gene fragment showed the highest detection performance with a detection rate of 16.6%; the nested map 1 PCR, which amplified the gene encoding the major antigenic protein1 ( map 1 gene) showed a detection rate of 11% and the RLB, based on the 16S rDNA sequence of anaplasma and ehrlichial species, detected 6.2%. The RLB, in addition, demonstrated molecular evidence of Ehrlichia ovina , Anaplasma marginale and Anaplasma ovis infections in The Gambia. Subsequently, the pCS20 assay was applied to study the prevalence and distribution of E. ruminantium tick infection rates at different sites in five divisions of The Gambia. The rates of infection in the country ranged from 1.6% to 15.1% with higher prevalences detected at sites in the westerly divisions (Western, Lower River and North Bank; range 8.3–15.1%) than in the easterly divisions (Central River and Upper River; range 1.6–7.5%). This study demonstrated a gradient in the distribution of Heartwater Disease risk for susceptible livestock in The Gambia which factor must be considered in the overall design of future upgrading programmes.
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Transcription Analysis of the Major Antigenic Protein 1 Multigene Family of Three In Vitro-Cultured Ehrlichia ruminantium Isolates
Journal of bacteriology, 2005Co-Authors: Cornelis P. J. Bekker, Dominique Martinez, Conchita Ferraz, Amar Taoufik, Milagros Postigo, Lesley Bell-sakyi, F JongejanAbstract: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.
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phylogenetic position of cowdria ruminantium rickettsiales determined by analysis of amplified 16s ribosomal dna sequences
International Journal of Systematic and Evolutionary Microbiology, 1992Co-Authors: Arnoud H M Van Vliet, F Jongejan, Bernard A M Van Der ZeijstAbstract:The 16S ribosomal DNA sequence of Cowdria ruminantium, the causative agent of Heartwater Disease in ruminants, was determined. An analysis of this sequence showed that C. ruminantium forms a tight phylogenetic cluster with the canine pathogen Ehrlichia canis and the human pathogen Ehrlichia chaffeensis. Although a close relationship between the genus Cowdria and several members of the tribe Ehrlichieae has been suspected previously, the tight phylogenetic cluster with E. canis and E. chaffeensis is surprising in view of known differences in host preference and target cells.
Dominique Martinez - One of the best experts on this subject based on the ideXlab platform.
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Transcription Analysis of the Major Antigenic Protein 1 Multigene Family of Three In Vitro-Cultured Ehrlichia ruminantium Isolates
Journal of bacteriology, 2005Co-Authors: Cornelis P. J. Bekker, Dominique Martinez, Conchita Ferraz, Amar Taoufik, Milagros Postigo, Lesley Bell-sakyi, F JongejanAbstract: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.
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Association studies using random and "candidate" microsatellite loci in two infectious goat Diseases
Genetics Selection Evolution, 2003Co-Authors: Gabriela Obexer-ruff, Dominique Martinez, Ursula Sattler, Jean-charles Maillard, Christophe Chartier, Nasikat Saitbekova, Marie-louise Glowatzki, Claude GaillardAbstract:We established a set of 30 microsatellites of Bovidae origin for use in a biodiversity study in Swiss and Creole goats. Additional microsatellites located within or next to "candidate" genes of interest, such as cytokine genes (IL4, INF-gamma) and MHC class II genes (DRB, DYA) were tested in the caprine species in order to detect possible associations with two infectious caprine Diseases. Microsatellite analysis was undertaken using automated sequencers (ABI373 & 3100). In the first study, a total of 82 unrelated Creole goats, 37 resistant and 45 susceptible to Heartwater Disease (Cowdriosis) were analysed. In this study, the two microsatellite loci DRBP1 (MHCII) and BOBT24 (IL4) were positively associated with Disease susceptibility, demonstrating a corrected $P$-value of 0.002 and 0.005, respectively. In a second investigation, we tested 36 goats, naturally infected with the nematode parasite Trichostrongylus colubriformis. These animals were divided into a "low" and "high" excreting group on the basis of two independently recorded fecal egg counts. For this nematode resistance study, we detected a significant association of one of the alleles of the microsatellite locus SPS113 with "low" excretion (resistance). The MHC class II locus DYA (P19), was weakly associated with susceptibility in both Diseases ($P_{\rm c} = 0.05$). In future experiments, we will extend the sample size in order to verify the described associations.
S M Mahan - One of the best experts on this subject based on the ideXlab platform.
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diversity of ehrlichia ruminantium major antigenic protein 1 2 in field isolates and infected sheep
Infection and Immunity, 2009Co-Authors: Anthony F Barbet, Barbara Byrom, S M MahanAbstract:Proteins expressed from the map1 multigene family of Ehrlichia ruminantium are strongly recognized by immune T and B cells from infected animals or from animals that were infected and have recovered from Heartwater Disease (although still remaining infected carriers). Analogous multigene clusters also encode the immunodominant outer membrane proteins (OMPs) in other ehrlichial species. Recombinant protein analogs of the expressed genes and DNA vaccines based on the multigene clusters have been shown to induce protective immunity, although this was less effective in heterologous challenge situations, where the challenge strain major antigenic protein 1 (MAP1) sequence differed from the vaccine strain MAP1. Recent data for several ehrlichial species show differential expression of the OMPs in mammalian versus tick cell cultures and dominant expression of individual family members in each type of culture system. However, many genes in the clusters appear to be complete and functional and to generate mRNA transcripts. Recent data also suggest that there may be a low level of protein expression from many members of the multigene family, despite primary high-level expression from an individual member. A continuing puzzle, therefore, is the biological roles of the different members of these OMP multigene families. Complete genome sequences are now available for two geographically divergent strains of E. ruminantium (Caribbean and South Africa strains). Comparison of these sequences revealed amino acid sequence diversity in MAP1 (89% identity), which is known to confer protection in a mouse model and to be the multigene family member primarily expressed in mammalian cells. Surprisingly, however, the greatest sequence diversity (79% identity) was in the less-studied map1-2 gene. We investigated here whether this map1-2 diversity was a general feature of E. ruminantium in different cultured African strains and in organisms from infected sheep. Comparison of MAP1-2s revealed amino acid identities of 75 to 100% (mean of 86%), compared to 84 to 100% (mean of 89%) for MAP1s. Interestingly, MAP1-2s varied independently of MAP1s such that E. ruminantium strains with similar MAP1s had diverse MAP1-2s and vice versa. Different MAP1-2s were found in individual infected sheep. Different regions of a protein may be subjected to different evolutionary forces because of recombination and/or selection, which results in those regions not agreeing with a phylogeny deduced from the whole molecule. This appears to be true for both MAP1 and MAP1-2, where statistical likelihood methods detect heterogeneous evolutionary rates for segments of both molecules. Sera from infected cattle recognized a MAP1-2 variable-region peptide in enzyme-linked immunosorbent assay, but less strongly and consistently than a MAP1 peptide (MAP1B). Heterologous protective immunity may depend on recognition of a complex set of varying OMP epitopes.
Jeanette Wentzel - One of the best experts on this subject based on the ideXlab platform.
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amblyomma hebraeum is the predominant tick species on goats in the mnisi community area of mpumalanga province south africa and is co infected with ehrlichia ruminantium and rickettsia africae
Parasites & Vectors, 2020Co-Authors: F Jongejan, Laura Berger, Suzanne Busser, Iris Deetman, Manon Jochems, Tiffany Leenders, Barry De Sitter, Francine Van Der Steen, Jeanette WentzelAbstract:In sub-Saharan Africa, Amblyomma ticks are vectors of Heartwater Disease in domestic ruminants, caused by the rickettsial pathogen Ehrlichia ruminantium. Immature tick stages often bite humans, whereby they act as vectors of tick-bite fever caused by Rickettsia africae. Moreover, Amblyomma ticks cause damage to livestock due to their feeding behaviour. In South Africa, we studied the abundance of Amblyomma hebraeum ticks on goats of emerging farmers in Mpumalanga Province. A selected number of A. hebraeum nymphs and adult ticks was tested for co-infection with E. ruminantium and R. africae. A total of 630 indigenous goats, belonging to farmers in the Mnisi Community area, were examined for ticks in 2013 and 2014. All ticks were identified, and a selected number was tested by PCR with reverse line blot hybridisation. In total, 13,132 ticks were collected from goats distributed over 17 different households. Amblyomma hebraeum was the predominant species, followed by R. microplus. Rhipicephalus appendiculatus, R. simus and R. zambeziensis were also identified. Amblyomma hebraeum was present throughout the year, with peak activity of adults in summer (November) and nymphs in winter (July). The ratio between adults and nymphs ranged from 1:2.7 in summer to 1:55.1 in winter. The mean prevalence of infection for E. ruminantium by PCR/RLB in adult ticks was 17.4% (31/178), whereas 15.7% (28/178) were infected with R. africae. In pooled nymphs, 28.4% were infected with E. ruminantium and 38.8% carried R. africae infection. Co-infections of E. ruminantium and R. africae in adult and pooled nymphal ticks were 3.9% (7/178) and 10% (14.9), respectively. Lameness of goats due to predilection of ticks for the interdigital space of their feet was observed in 89% of the households. Goats act as important alternative hosts for cattle ticks, which underscored the necessity to include goats in control programs. It is suggested to use acaricide-impregnated leg-bands as a sustainable method to kill ticks and prevent lameness in goats. The challenge of goats by considerable numbers of E. ruminantium-infected ticks is a major obstacle for upgrading the indigenous goat breeds. Humans may be at risk to contract tick-bite fever in this area.
Claude Gaillard - One of the best experts on this subject based on the ideXlab platform.
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Association studies using random and "candidate" microsatellite loci in two infectious goat Diseases
Genetics Selection Evolution, 2003Co-Authors: Gabriela Obexer-ruff, Dominique Martinez, Ursula Sattler, Jean-charles Maillard, Christophe Chartier, Nasikat Saitbekova, Marie-louise Glowatzki, Claude GaillardAbstract:We established a set of 30 microsatellites of Bovidae origin for use in a biodiversity study in Swiss and Creole goats. Additional microsatellites located within or next to "candidate" genes of interest, such as cytokine genes (IL4, INF-gamma) and MHC class II genes (DRB, DYA) were tested in the caprine species in order to detect possible associations with two infectious caprine Diseases. Microsatellite analysis was undertaken using automated sequencers (ABI373 & 3100). In the first study, a total of 82 unrelated Creole goats, 37 resistant and 45 susceptible to Heartwater Disease (Cowdriosis) were analysed. In this study, the two microsatellite loci DRBP1 (MHCII) and BOBT24 (IL4) were positively associated with Disease susceptibility, demonstrating a corrected $P$-value of 0.002 and 0.005, respectively. In a second investigation, we tested 36 goats, naturally infected with the nematode parasite Trichostrongylus colubriformis. These animals were divided into a "low" and "high" excreting group on the basis of two independently recorded fecal egg counts. For this nematode resistance study, we detected a significant association of one of the alleles of the microsatellite locus SPS113 with "low" excretion (resistance). The MHC class II locus DYA (P19), was weakly associated with susceptibility in both Diseases ($P_{\rm c} = 0.05$). In future experiments, we will extend the sample size in order to verify the described associations.
