» Articles » PMID: 8253974

An Immunoblotting Diagnostic Assay for Heartwater Based on the Immunodominant 32-kilodalton Protein of Cowdria Ruminantium Detects False Positives in Field Sera

Overview
Specialty Microbiology
Date 1993 Oct 1
PMID 8253974
Citations 22
Authors
Affiliations
Soon will be listed here.
Abstract

Heartwater, a major constraint to improved livestock production in Zimbabwe, threatens to invade areas which have been previously unaffected. To monitor its spread in Zimbabwe, an immunoblotting diagnostic assay based on the responses of animals to the immunodominant, conserved 32-kDa protein of Cowdria ruminantium was evaluated. In this assay, no false reactions were detected with sera known to be positive and negative, but sera from some cattle, sheep, and goats from heartwater-free areas of Zimbabwe reacted strongly with the 32-kDa protein, suggesting that either these animals had previous exposure to heartwater or they were false positives. To investigate the possibility of previous exposure to heartwater, 11 immunoblot-positive and 6 immunoblot-negative sheep from heartwater-free areas of Zimbabwe were compared regarding their susceptibilities to challenge with C. ruminantium. Prior to challenge, C. ruminantium could not be detected in any sheep by transmission to Amblyomma hebraeum ticks or by the polymerase chain reaction (PCR) conducted with plasma samples. All sheep were equally susceptible to the challenge, and infection was confirmed by brain biopsy, necropsy, PCR, and transmission of C. ruminantium to ticks. Our data suggest that the immunoblot-positive reactions of sera from heartwater-free areas were due not to previous C. ruminantium infection but rather to antigenic cross-reactivity between C. ruminantium and another agent(s) such as Ehrlichia species. In conclusion, the immunodominant 32-kDa protein is not antigenically specific to C. ruminantium and its use in serological diagnosis of heartwater requires reevaluation.

Citing Articles

Progress and obstacles in vaccine development for the ehrlichioses.

McBride J, Walker D Expert Rev Vaccines. 2010; 9(9):1071-82.

PMID: 20822349 PMC: 2951016. DOI: 10.1586/erv.10.93.


Longitudinal monitoring of Ehrlichia ruminantium infection in Gambian lambs and kids by pCS20 PCR and MAP1-B ELISA.

Faburay B, Geysen D, Munstermann S, Bell-Sakyi L, Jongejan F BMC Infect Dis. 2007; 7:85.

PMID: 17662144 PMC: 1949406. DOI: 10.1186/1471-2334-7-85.


Detection by two enzyme-linked immunosorbent assays of antibodies to Ehrlichia ruminantium in field sera collected from sheep and cattle in Ghana.

Bell-Sakyi L, Koney E, Dogbey O, Sumption K, Walker A, Bath A Clin Diagn Lab Immunol. 2003; 10(5):917-25.

PMID: 12965927 PMC: 193896. DOI: 10.1128/cdli.10.5.917-925.2003.


Development of a polyclonal competitive enzyme-linked immunosorbent assay for detection of antibodies to Ehrlichia ruminantium.

Sumption K, Paxton E, Bell-Sakyi L Clin Diagn Lab Immunol. 2003; 10(5):910-6.

PMID: 12965926 PMC: 193895. DOI: 10.1128/cdli.10.5.910-916.2003.


Population-based evaluation of the Ehrlichia ruminantium MAP 1B indirect ELISA.

Peter T, OCallaghan C, Medley G, Perry B, Semu S, Maha S Exp Appl Acarol. 2002; 25(10-11):881-97.

PMID: 12455878 DOI: 10.1023/a:1020424718957.


References
1.
Norval R . Tick infestations and tick-borne diseases in Zimbabwe Rhodesia. J S Afr Vet Assoc. 1979; 50(4):289-92. View

2.
Jongejan F, Thielemans M, de Groot M, van Kooten P, van der Zeijst B . Competitive enzyme-linked immunosorbent assay for heartwater using monoclonal antibodies to a Cowdria ruminantium-specific 32-kilodalton protein. Vet Microbiol. 1991; 28(2):199-211. DOI: 10.1016/0378-1135(91)90093-u. View

3.
van Winkelhoff A, Uilenberg G . Heartwater: cross-immunity studies with strains of Cowdria ruminantium isolated in West and South Africa. Trop Anim Health Prod. 1981; 13(3):160-4. DOI: 10.1007/BF02237914. View

4.
Uilenberg G . Heartwater (Cowdria ruminantium infection): current status. Adv Vet Sci Comp Med. 1983; 27:427-80. View

5.
Waghela S, Rurangirwa F, Mahan S, YUNKER C, Crawford T, Barbet A . A cloned DNA probe identifies Cowdria ruminantium in Amblyomma variegatum ticks. J Clin Microbiol. 1991; 29(11):2571-7. PMC: 270375. DOI: 10.1128/jcm.29.11.2571-2577.1991. View