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Canine antibody response to Blastomyces dermatitidis WI-1 antigen

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  • 1 Departments of Internal Medicine, Medical Microbiology and Immunology, University of Wisconsin Medical School, Madison, WI 53792.
  • | 2 Department of Pediatrics, University of Wisconsin Medical School, Madison, WI 53792.
  • | 3 Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
  • | 4 Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
  • | 5 Department of Pediatrics, University of Wisconsin Medical School, Madison, WI 53792.
  • | 6 Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996.

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)