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Collins M, Ngetich C, Owido M, Getange D, Harris R, Bargul JL, Bodha B, Njoroge D, Muloi D, Martins DJ, Villinger J, Githaka N, Baylis M, Fèvre EM, Kanduma E, Younan M, Bell-Sakyi L. Detection of Antibodies to Ehrlichia spp. in Dromedary Camels and Co-Grazing Sheep in Northern Kenya Using an Ehrlichia ruminantium Polyclonal Competitive ELISA. Microorganisms 2022; 10:microorganisms10050916. [PMID: 35630361 PMCID: PMC9144424 DOI: 10.3390/microorganisms10050916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 04/22/2022] [Accepted: 04/26/2022] [Indexed: 12/13/2022] Open
Abstract
A disease with clinical and post-mortem presentation similar to those seen in heartwater, a tick-borne disease of domestic and wild ruminants caused by the intracellular bacterium Ehrlichia ruminantium, was first reported in dromedary camels in Kenya in 2016; investigations carried out at the time to determine the cause were inconclusive. In the present study, we screened sera from Kenyan camels collected before (2015) and after (2020) the 2016 disease outbreak for antibodies to Ehrlichia spp. using an E. ruminantium polyclonal competitive ELISA (PC-ELISA). Median antibody levels were significantly higher (p < 0.0001) amongst camels originating from areas where the heartwater-like disease was reported than from disease-free areas, for animals sampled in both 2015 and 2020. Overall median seropositivity was higher in camels sampled in 2015 than in 2020, which could have been due to higher mean age in the former group. Camels that were PCR-positive for Candidatus Ehrlichia regneryi had significantly lower (p = 0.03) median antibody levels than PCR-negative camels. Our results indicate that Kenyan camels are frequently exposed to E. ruminantium from an early age, E. ruminantium was unlikely to have been the sole cause of the outbreak of heartwater-like disease; and Ca. E. regneryi does not appreciably cross-react with E. ruminantium in the PC-ELISA.
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Affiliation(s)
- Marisol Collins
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
| | - Collins Ngetich
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Milton Owido
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Dennis Getange
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya; (D.G.); (J.L.B.)
| | - Robert Harris
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
| | - Joel L. Bargul
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya; (D.G.); (J.L.B.)
- International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya;
| | - Boku Bodha
- Directorate of Veterinary Services, County Government of Marsabit, Marsabit P.O. Box 384-60500, Kenya;
| | - Daniel Njoroge
- Department of Biochemistry and Molecular Biology, Faculty of Science, Egerton University, Njoro P.O. Box 536-20115, Kenya;
| | - Dishon Muloi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | | | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya;
| | - Naftaly Githaka
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Matthew Baylis
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
| | - Eric M. Fèvre
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Esther Kanduma
- Department of Biochemistry, Faculty of Science and Technology, University of Nairobi, Nairobi P.O. Box 30197-00100, Kenya;
| | - Mario Younan
- Food and Agriculture Organisation of the United Nations (FAO), Programme and Operational Support to Syria Crisis, UN Cross-Border Hub, Gaziantep 27010, Turkey;
| | - Lesley Bell-Sakyi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
- Correspondence:
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Boucher F, Moutroifi Y, Peba B, Ali M, Moindjie Y, Ruget AS, Abdouroihamane S, Madi Kassim A, Soulé M, Charafouddine O, Cêtre-Sossah C, Cardinale E. Tick-borne diseases in the Union of the Comoros are a hindrance to livestock development: Circulation and associated risk factors. Ticks Tick Borne Dis 2019; 11:101283. [PMID: 31519420 DOI: 10.1016/j.ttbdis.2019.101283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 08/20/2019] [Accepted: 08/24/2019] [Indexed: 10/26/2022]
Abstract
Tick-borne diseases (TBD) occur in many temperate countries and are economically important in most tropical and subtropical areas, affecting dairy and beef cattle, as well as small ruminants. Four major tick-borne diseases have been detected in eastern and southern Africa: East Coast fever (ECF) caused by Theileria parva, Theiler 1904, anaplasmosis caused by either Anaplasma marginale, Theiler 1910, Anaplasma centrale, Theiler 1911, or Anaplasma ovis, Bevan 1912, babesiosis caused by Babesia bovis, Babes 1988 and Babesia bigemina, Smith & Kilborne 1893, and heartwater caused by Ehrlichia ruminantium Cowdry 1925. A cross-sectional survey was undertaken to determine the antibody prevalence of these TBDs and to identify the risk factors for TBD infections in the Union of the Comoros. In 2016 and 2017, 903 individual animal serum samples were collected from 429 separate farms, where the farmers answered individual questionnaires. The antibody prevalence of anaplasmosis, babesiosis (B. bigemina) and heartwater was determined by enzyme-linked immunosorbent assays (ELISA) and the antibody prevalence of ECF was assessed using an immunofluorescence antibody test (IFAT). The relationship between TBD seropositivity and livestock-related variables was assessed by multivariate analyses with standard logistic regression models. The results showed that these four TBDs were present in the Union of the Comoros with a global antibody prevalence of 15% (95% CI [12.7%; 17.3%]) for anaplasmosis, 9.2% (95% CI [6.5%, 11.9%]) for B. bigemina babesiosis, 5.3% (95% CI [3.2%, 7.4%]) for ECF and 4.6% (95% CI [3.2%, 6%]) for heartwater. We compared these findings with the abundance and distribution of several tick species known to be TBD vectors and we found a significant correlation between Rhipicephalus appendiculatus and ECF, and between Amblyomma variegatum and heartwater. We also found that two major variables were significantly correlated with B. bigemina antibody prevalence ("island" and "breeding area"), four variables were significantly correlated with anaplasmosis antibody seroprevalence ("island", "number of cattle per farmer", "number of farmers per village" and "breeding area"), two were significantly correlated with ECF antibody prevalence ("number of farmers in village" and "presence of ticks"), and three were significantly correlated with heartwater ("island", "number of cattle per farmer" and "number of farmers in the village"). Our findings confirmed livestock exposure to the four targeted TBDs of major concern for livestock development. Consequently, raising farmers' awareness and setting up a period of quarantine should be considered a priority.
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Affiliation(s)
- F Boucher
- CIRAD, UMR ASTRE, Sainte Clotilde, La Réunion, France; ASTRE, Univ Montpellier (I-MUSE), CIRAD, INRA, Montpellier, France; Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - Y Moutroifi
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - B Peba
- Onderstepoort Veterinary Institute, 100 Old Soutpan Road, Private Bag X5, 0110 Onderstepoort, South Africa
| | - M Ali
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - Y Moindjie
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - A-S Ruget
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - S Abdouroihamane
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - A Madi Kassim
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - M Soulé
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - O Charafouddine
- Direction nationale de l'élevage, Direction nationale des stratégies agricoles et de l'élevage, Vice-présidence en charge du ministère de l'agriculture, de la pêche, de l'environnement de l'aménagement du territoire et de l'urbanisme, Mdé, Bambao, Comoros
| | - C Cêtre-Sossah
- CIRAD, UMR ASTRE, Sainte Clotilde, La Réunion, France; ASTRE, Univ Montpellier (I-MUSE), CIRAD, INRA, Montpellier, France
| | - E Cardinale
- CIRAD, UMR ASTRE, Sainte Clotilde, La Réunion, France; ASTRE, Univ Montpellier (I-MUSE), CIRAD, INRA, Montpellier, France.
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Vachiery N, Maganga G, Lefrançois T, Kandassamy Y, Stachurski F, Adakal H, Ferraz C, Morgat A, Bensaid A, Coissac E, Boyer F, Demaille J, Viari A, Martinez D, Frutos R. Differential strain-specific diagnosis of the heartwater agent: Ehrlichia ruminantium. INFECTION GENETICS AND EVOLUTION 2008; 8:459-66. [PMID: 17644446 DOI: 10.1016/j.meegid.2007.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 06/08/2007] [Accepted: 06/11/2007] [Indexed: 11/28/2022]
Abstract
Ehrlichia ruminantium is the causative agent of heartwater, a major tick-borne disease of livestock in Africa introduced in the Caribbean and threatening to emerge and spread in the American mainland. Complete genome sequencing was done for two isolates of E. ruminantium of differing phenotype, isolates Gardel (Erga) from Guadeloupe Island and Welgevonden (Erwe) originating from South Africa and maintained in Guadeloupe. The type strain of E. ruminantium (Erwo), previously isolated and sequenced in South Africa; is identical to Erwe with respect to target genes. They make the Erwe/Erwo complex. Comparative analysis of the genomes shows the presence of 49 unique CDS and 28 truncated CDS differentiating Erga from Erwe/Erwo. Three regions of accumulated differences (RAD) acting as mutational hot spots were identified in E. ruminantium. Ten CDS, six unique CDS and four truncated CDS corresponding to major genomic changes (deletions or extensive mutations) were considered as targets for differential diagnosis on four isolates of E. ruminantium: Erga, Erwe/Erwo, Senegal and Umpala. Pairs of PCR primers were developed for each target gene. PCR analysis of the target genes generated strain-specific patterns on Erga and Erwe/Erwo as predicted by comparative genomics, but also for isolates Senegal and Umpala. The target genes identified by bacterial comparative genomics are shown to be highly efficient for strain-specific PCR diagnosis of E. ruminantium and further vaccine management tools.
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Affiliation(s)
- Nathalie Vachiery
- CIRAD TA A-15/G, Campus International de Baillarguet, 34398, Montpellier Cedex 05, France
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Longitudinal monitoring of Ehrlichia ruminantium infection in Gambian lambs and kids by pCS20 PCR and MAP1-B ELISA. BMC Infect Dis 2007; 7:85. [PMID: 17662144 PMCID: PMC1949406 DOI: 10.1186/1471-2334-7-85] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 07/27/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The epidemiology of E. ruminantium infection in extensively managed young animals is not adequately understood. Thus in this study, we monitored the onset (age at first infection) and kinetics of E. ruminantium infection and antibody response in extensively managed newborn lambs and kids at three sites in The Gambia. METHODS We used a nested pCS20 PCR and MAP1-B ELISA in a longitudinal study to monitor the onset (age at first infection) and kinetics of E. ruminantium infection and antibody response respectively, in 77 newborn lambs and kids under a traditional husbandry system at three sites (Kerr Seringe, Keneba, Bansang) in The Gambia where heartwater is known to occur. The animals were monitored for field tick infestation and the comparative performance of the two assays in detecting E. ruminantium infection was also assessed. RESULTS The infection rate detected by pCS20 PCR varied between 8.6% and 54.8% over the 162-day study period. Nineteen per cent of the animals in week 1 post-partum tested positive by pCS20 PCR with half of these infections (7/14) detected in the first 3 days after birth, suggesting that transmission other than by tick feeding had played a role. The earliest detectable A. variegatum infestation in the animals occurred in week 16 after birth. Antibodies detected by MAP1-B ELISA also varied, between 11.5% and 90%. Although there is considerable evidence that this assay can detect false positives and due to this and other reasons serology is not a reliable predictor of infection at least for heartwater. In contrast to the pCS20 PCR, the serological assay detected the highest proportion of positive animals in week 1 with a gradual decline in seropositivity with increasing age. The pCS20 PCR detected higher E. ruminantium prevalence in the animals with increasing age and both the Spearman's rank test (rs = -0.1512; P = 0.003) and kappa statistic (-0.091 to 0.223) showed a low degree of agreement between the two assays. CONCLUSION The use of pCS20 PCR supported by transmission studies and clinical data could provide more accurate information on heartwater epidemiology in endemic areas and single-occasion testing of an animal may not reveal its true infection status. The view is supported because both the vector and vertical transmission may play a vital role in the epidemiology of heartwater in young small ruminants; the age range of 4 and 12 weeks corresponds to the period of increased susceptibility to heartwater in traditionally managed small ruminants.
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Frutos R, Viari A, Ferraz C, Bensaid A, Morgat A, Boyer F, Coissac E, Vachiéry N, Demaille J, Martinez D. Comparative genomics of three strains of Ehrlichia ruminantium: a review. Ann N Y Acad Sci 2007; 1081:417-33. [PMID: 17135545 DOI: 10.1196/annals.1373.061] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The tick-borne Rickettsiale Ehrlichia ruminantium (E. ruminantium) is the causative agent of heartwater in Africa and the Caribbean. Heartwater, responsible for major losses on livestock in Africa represents also a threat for the American mainland. Three complete genomes corresponding to two different groups of differing phenotypes, Gardel and Welgevonden, have been recently described. One genome (Erga) represents the Gardel group from Guadeloupe Island and two genomes (Erwo and Erwe) belong to the Welgevonden group. Erwo, isolated in South Africa, is the parental strain of Erwe, which was maintained for 18 years in Guadeloupe under different culture conditions than Erwo. The three strains display genomes of differing sizes with 1,499,920 bp, 1,512,977 bp, and 1,516,355 bp for Erga, Erwe, and Erwo, respectively. Gene sequences and order are highly conserved between the three strains, although several gene truncations could be pinpointed, most of them occurring within three regions of accumulated differences (RAD). E. ruminantium displays a strong leading/lagging compositional bias inducing a strand-specific codon usage. Finally, a striking feature of E. ruminantium is the presence of long intergenic regions containing tandem repeats. These repeats are at the origin of an active process, specific to E. ruminantium, of genome expansion/contraction based on the addition or removal of tandem units.
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Affiliation(s)
- Roger Frutos
- CIRAD, Emvt Department, TA30/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
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Frutos R, Viari A, Ferraz C, Morgat A, Eychenié S, Kandassamy Y, Chantal I, Bensaid A, Coissac E, Vachiery N, Demaille J, Martinez D. Comparative genomic analysis of three strains of Ehrlichia ruminantium reveals an active process of genome size plasticity. J Bacteriol 2006; 188:2533-42. [PMID: 16547041 PMCID: PMC1428390 DOI: 10.1128/jb.188.7.2533-2542.2006] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ehrlichia ruminantium is the causative agent of heartwater, a major tick-borne disease of livestock in Africa that has been introduced in the Caribbean and is threatening to emerge and spread on the American mainland. We sequenced the complete genomes of two strains of E. ruminantium of differing phenotypes, strains Gardel (Erga; 1,499,920 bp), from the island of Guadeloupe, and Welgevonden (Erwe; 1,512,977 bp), originating in South Africa and maintained in Guadeloupe in a different cell environment. Comparative genomic analysis of these two strains was performed with the recently published parent strain of Erwe (Erwo) and other Rickettsiales (Anaplasma, Wolbachia, and Rickettsia spp.). Gene order is highly conserved between the E. ruminantium strains and with A. marginale. In contrast, there is very little conservation of gene order with members of the Rickettsiaceae. However, gene order may be locally conserved, as illustrated by the tuf operons. Eighteen truncated protein-encoding sequences (CDSs) differentiate Erga from Erwe/Erwo, whereas four other truncated CDSs differentiate Erwe from Erwo. Moreover, E. ruminantium displays the lowest coding ratio observed among bacteria due to unusually long intergenic regions. This is related to an active process of genome expansion/contraction targeted at tandem repeats in noncoding regions and based on the addition or removal of ca. 150-bp tandem units. This process seems to be specific to E. ruminantium and is not observed in the other Rickettsiales.
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Affiliation(s)
- Roger Frutos
- CIRAD TA30/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
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Faburay B, Munstermann S, Geysen D, Bell-Sakyi L, Ceesay A, Bodaan C, Jongejan F. Point seroprevalence survey of Ehrlichia ruminantium infection in small ruminants in The Gambia. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 12:508-12. [PMID: 15817758 PMCID: PMC1074385 DOI: 10.1128/cdli.12.4.508-512.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using the MAP1-B enzyme-linked immunosorbent assay, we tested 1,318 serum samples collected from sheep and goats at 28 sites in the five divisions of The Gambia to determine the Ehrlichia ruminantium seroprevalence rates and to assess the risk for heartwater. About half (51.6%) of 639 sheep were positive, with seroprevalence rates per site varying between 6.9% and 100%. The highest seroprevalence was detected in the western part of the country (88.1% in the Western Division and 62.1% in the Lower River Division). Sheep in the two easterly divisions (Central River and Upper River divisions) showed the lowest seroprevalence of 29.3% and 32.4%, respectively, while those in the North Bank Division showed an intermediate prevalence of 40.6%. In goats, less than one-third (30.3%) of 679 animals tested were positive. The highest seroprevalence was detected in goats in the North Bank Division (59%) and Western Division (44.1%). Goats in the Lower River Division showed an intermediate level of 21.9%, whereas the lowest rates were found in the eastern part of the country (4.8% in the Central River Division and 2.3% in the Upper River Division). At nearly all sites, seroprevalence rates were higher in sheep than in goats. The results show a gradient of increasing heartwater risk for susceptible small ruminants from the east to the west of The Gambia. These findings need to be taken into consideration when future livestock-upgrading programs are implemented.
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Affiliation(s)
- Bonto Faburay
- International Trypanotolerance Centre, PMB 14, Banjul, The Gambia.
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Bell-Sakyi L, Koney EBM, Dogbey O, Sumption KJ, Walker AR, Bath A, Jongejan F. Detection by two enzyme-linked immunosorbent assays of antibodies to Ehrlichia ruminantium in field sera collected from sheep and cattle in Ghana. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2003; 10:917-25. [PMID: 12965927 PMCID: PMC193896 DOI: 10.1128/cdli.10.5.917-925.2003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Two serological tests for detection of antibodies to Ehrlichia (previously Cowdria) ruminantium, the causative agent of heartwater, were compared by using field sera collected from sheep and cattle as part of serosurveys in Ghana. Sera selected as either negative or positive by a new polyclonal competitive enzyme-linked immunosorbent assay (PC-ELISA) were tested by the indirect MAP1-B ELISA. Cutoff values of 14 percent positivity (14 PP) for both ruminant species were obtained for the MAP1-B ELISA by using preseroconversion Ghanaian sera and were compared with previously recommended cutoff values of 29 PP for sheep and 38 PP for cattle. With the 14-PP cutoff, of 151 sheep sera which tested negative by PC-ELISA, 89% were also negative by MAP1-B ELISA, while of 419 sheep sera positive by PC-ELISA, 98% were also positive by MAP1-B ELISA. Of 261 bovine sera negative by PC-ELISA, 82% were also negative by MAP1-B ELISA. Of 511 bovine sera positive by PC-ELISA, only 47% were positive by MAP1-B ELISA; these included 168 sera collected from cattle following first seroconversion as detected by both tests, with 125 of these sera positive by PC-ELISA but only 59 and 5 positive by MAP1-B ELISA with the 14- and 38-PP cutoff levels, respectively. These results indicate that both assays are highly sensitive and specific for detection of E. ruminantium exposure in sheep but that the MAP1-B ELISA lacks sensitivity for postseroconversion bovine sera in comparison to the PC-ELISA. Both tests confirm E. ruminantium seroprevalence of at least 70% in Ghanaian sheep; levels of exposure among Amblyomma variegatum-infested Ghanaian cattle are likely to be higher than the seroprevalence value of 66% obtained with the PC-ELISA.
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Affiliation(s)
- Lesley Bell-Sakyi
- Veterinary Services Department, Ministry of Food and Agriculture, Accra, Ghana.
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Sumption KJ, Paxton EA, Bell-Sakyi L. Development of a polyclonal competitive enzyme-linked immunosorbent assay for detection of antibodies to Ehrlichia ruminantium. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2003; 10:910-6. [PMID: 12965926 PMCID: PMC193895 DOI: 10.1128/cdli.10.5.910-916.2003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A polyclonal competitive enzyme-linked immunosorbent assay (PC-ELISA) is described for detection of antibodies to Ehrlichia (Cowdria) ruminantium by using a soluble extract of endothelial cell culture-derived E. ruminantium as the antigen and biotin-labeled polyclonal goat immunoglobulins as the competitor. For goats, the diagnostic sensitivity and specificity were both 100% with a cutoff of 80% inhibition (80 PI), with detection of antibodies for 550 days postinfection. For cattle, diagnostic sensitivity and specificity were 86 and 100%, respectively, with a cutoff of 50 PI and 79 and 100% with a cutoff of 70 PI. Cross-reactions with high-titer experimental or field antisera to other Ehrlichia and Anaplasma species were observed at up to 68 PI in cattle and up to 85 PI in sheep, and therefore to exclude these cross-reactions, cutoffs of 70 PI for bovine serology and 85 PI for small-ruminant serology were selected. Application of the PC-ELISA to bovine field sera from South Africa gave a higher proportion of positive results than application of the murine macrophage immunofluorescent antibody test or indirect ELISA, suggesting a better sensitivity for detection of recovered cattle, and results with bovine field sera from Malawi were consistent with the observed endemic state of heartwater and the level of tick control practiced at the sample sites. Reproducibility was high, with average standard deviations intraplate of 1.2 PI and interplate of 0.6 PI. The test format is simple, and the test is economical to perform and has a level of sensitivity for detection of low-titer positive bovine sera that may prove to be of value in epidemiological studies on heartwater.
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Affiliation(s)
- Keith J Sumption
- Centre for Tropical Veterinary Medicine, University of Edinburgh, Easter Bush, Roslin, Midlothian EH25 9RG, Scotland, United Kingdom
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Semu SM, Peter TF, Mukwedeya D, Barbet AF, Jongejan F, Mahan SM. Antibody responses to MAP 1B and other Cowdria ruminantium antigens are down regulated in cattle challenged with tick-transmitted heartwater. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2001; 8:388-96. [PMID: 11238227 PMCID: PMC96068 DOI: 10.1128/cdli.8.2.388-396.2001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Serological diagnosis of heartwater or Cowdria ruminantium infection has been hampered by severe cross-reactions with antibody responses to related ehrlichial agents. A MAP 1B indirect enzyme-linked immunosorbent assay that has an improved specificity and sensitivity for detection of immunoglobulin G (IgG) antibodies has been developed to overcome this constraint (A. H. M. van Vliet, B. A. M. Van der Zeijst, E. Camus, S. M. Mahan, D. Martinez, and F. Jongejan, J. Clin. Microbiol. 33:2405-2410, 1995). When sera were tested from cattle in areas of endemic heartwater infection in Zimbabwe, only 33% of the samples tested positive in this assay despite a high infection pressure (S. M. Mahan, S. M. Samu, T. F. Peter, and F. Jongejan, Ann. N.Y. Acad. Sci 849:85-87, 1998). To determine underlying causes for this observation, the kinetics of MAP 1B-specific IgG antibodies in cattle after tick-transmitted C. ruminantium infection and following recovery were investigated. Sera collected weekly over a period of 52 weeks from 37 cattle, which were naturally or experimentally infected with C. ruminantium via Amblyomma hebraeum ticks, were analyzed. MAP 1B-specific IgG antibody responses developed with similar kinetics in both field- and laboratory-infected cattle. IgG levels peaked at 4 to 9 weeks after tick infestation and declined to baseline levels between 14 and 33 weeks, despite repeated exposure to infected ticks and the establishment of a carrier state as demonstrated by PCR and xenodiagnosis. Some of the serum samples from laboratory, and field-infected cattle were also analyzed by immunoblotting and an indirect fluorescent-antibody test (IFAT) to determine whether this observed seroreversion was specific to the MAP 1B antigen. Reciprocal IFAT and immunoblot MAP 1-specific antibody titres peaked at 5 to 9 weeks after tick infestation but also declined between 30 and 45 weeks. This suggests that MAP 1B-specific IgG antibody responses and antibody responses to other C. ruminantium antigens are down regulated in cattle despite repeated exposure to C. ruminantium via ticks. Significantly, serological responses to the MAP 1B antigen may not be a reliable indicator of C. ruminantium exposure in cattle in areas of endemic heartwater infection.
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Affiliation(s)
- S M Semu
- University of Florida/USAID/SADC Heartwater Research Project, Box CY-551, Causeway, Harare, Zimbabwe
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Shompole S, Rurangirwa FR, Wambugu A, Sitienei J, Mwangi DM, Musoke AJ, Mahan S, Wells CW, McGuire TC. Monoclonal antibody binding to a surface-exposed epitope on Cowdria ruminantium that is conserved among eight strains. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2000; 7:983-6. [PMID: 11063511 PMCID: PMC95998 DOI: 10.1128/cdli.7.6.983-986.2000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Monoclonal antibodies (MAb) binding to Cowdria ruminantium elementary bodies (EB) were identified by enzyme-linked immunosorbent assay, and surface binding of one MAb (446.15) to intact EB was determined by immunofluorescence, immunogold labeling, and transmission electron microscopy. MAb 446.15 bound an antigen of approximately 43 kDa in immunoblots of eight geographically distinct strains. The MAb did not react with Ehrlichia canis antigens or uninfected bovine endothelial cell lysate and may be useful in diagnostic assays and vaccine development.
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Affiliation(s)
- S Shompole
- Biotechnology and Immunology Laboratory, Kenya Agricultural Research Institute, Kabete, Kenya.
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Mboloi MM, Bekker CP, Kruitwagen C, Greiner M, Jongejan F. Validation of the indirect MAP1-B enzyme-linked immunosorbent assay for diagnosis of experimental Cowdria ruminantium infection in small ruminants. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 1999; 6:66-72. [PMID: 9874666 PMCID: PMC95662 DOI: 10.1128/cdli.6.1.66-72.1999] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The major antigenic protein 1 fragment B (MAP1-B) enzyme-linked immunosorbent assay (ELISA) for the diagnosis of Cowdria ruminantium infections was validated to determine cutoff values and evaluate its diagnostic performance with sheep and goat sera. Cowdria-infected populations consisted of 48 sheep and 44 goats, while the noninfected populations consisted of 64 sheep and 107 goats. Cutoff values were determined by two-graph receiver-operating characteristic (TG-ROC) curves. The cutoff value was set at 31 and 26.6% of the positive control reference samples for sheep and goat sera, respectively. The test's diagnostic performance was evaluated with measurements of the area under the concentration-time curve (AUC) of the ROC curves and by the valid range proportion (VRP). The AUCs were 0.978 for sheep sera and 0.989 for goat sera. The VRP for both sheep and goat sera was approximately 1.0. The intermediate range (IR), which defines results that are neither positive nor negative, was 0 for goat sera and 2.81 for sheep sera. In an ideal test, the AUC and VRP would be 1.0 and the IR would be 0. In this study these parameters were close to those of an ideal test. It is concluded that the MAP1-B ELISA is a useful test for the diagnosis of C. ruminantium infection in small ruminants.
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Affiliation(s)
- M M Mboloi
- Department of Parasitology and Tropical Veterinary Medicine, and Center for Biostatistics, Utrecht University, Utrecht, The Netherlands
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