Canine antibody response to Blastomyces dermatitidis WI-1 antigen

Bruce S. Klein Departments of Internal Medicine, Medical Microbiology and Immunology, University of Wisconsin Medical School, Madison, WI 53792.
Department of Pediatrics, University of Wisconsin Medical School, Madison, WI 53792.

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Richard A. Squires Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.

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Janice K. Foyer Lloyd Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.

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Daniel R. Ruge Department of Pediatrics, University of Wisconsin Medical School, Madison, WI 53792.

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Alfred M. Legendre Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996.

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Abstract

Objective—To assess whether dogs with blastomycosis produce antibodies against the WI-1 and A-antigens of Blastomyces dermatitidis and whether the antibodies are useful in serodiagnosis.

Sample Population—359 serum samples obtained from 245 dogs.

Procedure—233 samples from 122 dogs with blastomycosis, and 1 sample each from 24 dogs with suspected blastomycosis, 51 control dogs without infection, and 48 healthy dogs from an enzootic region were obtained. Antibodies against WI-1 antigen were detected by radioimmunoassay (RIA). Serum samples were tested in parallel for antibodies against the Aantigen of B dermatitidis by commercial agar-gel immunodiffusion (AGID) in a reference laboratory.

Results—Antibodies were detected in 92% of infected dogs by RIA and in 41% by AGID. For 29 serum samples that were obtained 11 to 1,545 days after diagnosis, antibodies were detected in 92% of samples by RIA and 7% by AGID. For 93 serial serum samples from 29 dogs with blastomycosis, the mean anti-WI-1 titer was 1:18,761 at the time of diagnosis, and decreased to a mean of 1:1,338 by 210 days after treatment was initiated. Of 24 dogs with suspected infection, antibodies were detected in 67% by RIA and 33% by AGID. Control dogs without blastomycosis had no detectable antibodies in either assay. Thus, sensitivity was 92% for RIA and 41% for AGID, and specificity was 100% for both tests.

Conclusions and Clinical Relevance—Anti-WI-1 antibodies are readily detected by RIA in dogs with blastomycosis. Titers become high, decline during treatment, and persist for months. Anti-A antibodies are sometimes detected with AGID, but these decrease quickly. (Am J Vet Res 2000;61:554–558)

Abstract

Objective—To assess whether dogs with blastomycosis produce antibodies against the WI-1 and A-antigens of Blastomyces dermatitidis and whether the antibodies are useful in serodiagnosis.

Sample Population—359 serum samples obtained from 245 dogs.

Procedure—233 samples from 122 dogs with blastomycosis, and 1 sample each from 24 dogs with suspected blastomycosis, 51 control dogs without infection, and 48 healthy dogs from an enzootic region were obtained. Antibodies against WI-1 antigen were detected by radioimmunoassay (RIA). Serum samples were tested in parallel for antibodies against the Aantigen of B dermatitidis by commercial agar-gel immunodiffusion (AGID) in a reference laboratory.

Results—Antibodies were detected in 92% of infected dogs by RIA and in 41% by AGID. For 29 serum samples that were obtained 11 to 1,545 days after diagnosis, antibodies were detected in 92% of samples by RIA and 7% by AGID. For 93 serial serum samples from 29 dogs with blastomycosis, the mean anti-WI-1 titer was 1:18,761 at the time of diagnosis, and decreased to a mean of 1:1,338 by 210 days after treatment was initiated. Of 24 dogs with suspected infection, antibodies were detected in 67% by RIA and 33% by AGID. Control dogs without blastomycosis had no detectable antibodies in either assay. Thus, sensitivity was 92% for RIA and 41% for AGID, and specificity was 100% for both tests.

Conclusions and Clinical Relevance—Anti-WI-1 antibodies are readily detected by RIA in dogs with blastomycosis. Titers become high, decline during treatment, and persist for months. Anti-A antibodies are sometimes detected with AGID, but these decrease quickly. (Am J Vet Res 2000;61:554–558)

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