Diagnosis of Rhodococcus equi infection in foals by the agar gel diffusion test with protein antigen.
Abstract: A protein antigen that reacted in the agar gel diffusion (AGD) test and which had equi factor(s) activity, was partially purified from the culture supernatant of Rhodococcus equi by successive column chromatography on diethylaminoethyl cellulose and Sepharose 4B. Employing a standard foal serum, the concentration of this antigen was adjusted for the AGD test. Optimal dilutions of the antigen reacted in the AGD test with sera from foals naturally infected with serologically different R. equi. The antigen prepared was considered suitable for use in field surveys of R. equi infection. Accordingly, four groups of sera were tested: those from 18 foals diagnosed as being infected with R. equi, those from 54 control foals with culture-negative R. equi pneumonia, arthritis or cellulitis, those from 46 diseased foals suspected of having R. equi infection and those from 51 clinically normal foals. A positive precipitation reaction was observed with sera from 100% of the first group, 69.5% of the third group and 17.7% of the fourth group. A negative reaction was obtained with sera from 100% of the second group.
Publication Date: 1987-10-01 PubMed ID: 3125665DOI: 10.1016/0378-1135(87)90135-0Google Scholar: Lookup
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- Journal Article
Summary
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The research investigates the use of a protein antigen in the agar gel diffusion test for diagnosing Rhodococcus equi infection in foals. The protein antigen was partially purified from the Rhodococcus equi culture. The AGD test was then employed using this antigen, and results suggested its potential for identifying R. equi infection in field scenario.
Methodology
- The researchers began by partially purifying a protein antigen from the culture supernatant of Rhodococcus equi. This was done by conducting successive column chromatography on diethylaminoethyl cellulose and Sepharose 4B.
- The concentration of protein antigen required for the agar gel diffusion (AGD) test was then adjusted using a standard foal serum.
- Once the antigen was prepared, it was reacted in the AGD test with sera from foals naturally infected with serologically different R. equi. This step was crucial to ensure the effectiveness of the antigen.
Testing Procedure
- Four groups of equine sera were administered the AGD test using the protein antigen. These included sera from 18 foals diagnosed with R. equi infection, 54 control foals with pneumonia, arthritis or cellulitis but no R. equi, 46 diseased foals suspected to have R. equi infection, and 51 clinically normal foals.
- A positive precipitation reaction was expected if the test was successful. This means that the protein antigen reacted with the R. equi bacteria in the serum, causing precipitation.
Outcomes of the Test
- The results showed that sera from 100% of foals diagnosed with R. equi reacted positively in the AGD test, affirming the test’s reliability.
- A positive reaction was seen in 69.5% of sera from diseased foals suspected of R. equi infection and 17.7% of the sera from clinically normal foals. This indicated possible undetected infections.
- Interestingly, no reaction was observed in all sera from the group of control foals. This proves that the protein antigen does not react non-specifically, bolstering the test’s specificity.
Conclusion
- The research thus concluded that the protein antigen could be effectively used for diagnosing Rhodococcus equi infection in foals through the agar gel diffusion test.
- Such tests are critical for field surveys. It can expedite the diagnosis and thus the treatment initiation, securing better health for the foals.
Cite This Article
APA
Nakazawa M, Isayama Y, Kashiwazaki M, Yasui T.
(1987).
Diagnosis of Rhodococcus equi infection in foals by the agar gel diffusion test with protein antigen.
Vet Microbiol, 15(1-2), 105-113.
https://doi.org/10.1016/0378-1135(87)90135-0 Publication
Researcher Affiliations
- National Institute of Animal Health, Ibaraki, Japan.
MeSH Terms
- Actinomycetales Infections / diagnosis
- Actinomycetales Infections / veterinary
- Animals
- Antibodies, Bacterial / analysis
- Antigens, Bacterial / immunology
- Horse Diseases / diagnosis
- Horses
- Immunodiffusion
- Rhodococcus / immunology
Citations
This article has been cited 1 times.- Prescott JF. Rhodococcus equi: an animal and human pathogen.. Clin Microbiol Rev 1991 Jan;4(1):20-34.
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