J Vet Sci.  2004 Jun;5(2):111-117.

Comparative antibody response of five recombinant antigens in related to bacterial shedding levels and development of serological diagnosis based on 35 kDa antigen for Mycobacterium avium subsp. paratuberculosis

Affiliations
  • 1College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. yc42@cornell.edu
  • 2Department of Infectious Diseases, College of Veterinary Medicine and School of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Korea.

Abstract

Eighty-five complex (85A, 85B and 85C), 35-kDa and superoxide dismutase (SOD) were cloned, expressed and purified as antigens in an enzyme-linked immunosorbent assay (ELISA) to compare the serological reactivity of cows with different shedding levels of Mycobacterium avium subsp. paratuberculosis (MPT). Antibody responses to all recombinant antigens positively increased depending on shedding levels. In particular, antibody responses to the 35 kDa were higher than those to the others in all shedder groups. Also, the mean of O. D. values among Ag 85 complex, 85B showed slightly higher response than others with high sensitivity and specificity in all shedder groups. In receiver operating characteristic (ROC) curve analysis, the result of 35 kDa ELISA yielded an area under the curve value of 0.945 (95% confidence interval = 0.895 . 0.996), which indicated that this 35 kDa is more accurate indicator of MPT infection than other antigens. At the cut-off point recommended by the ROC curve analysis, the sensitivity and specificity of 35 kDa ELISA were higher than those of other antigens with 93.3% and 86.4%, respectively. Finally, a commercially available ELISA kit was used to clarify 200 positive and 200 negative sera. We then re-tested these serum samples with our ELISA test using the 35-kDa antigens. 35 kDa ELISA and commercial kit showed almost similar results in ROC curve analysis even though two of positive sera in commercial kit were negative in 35 kDa ELISA. The sera, which showed difference in the comparison with commercial ELISA kit, they also did not react with 35 kDa in Western blot. These results suggest that a 35-kDa based ELISA can be useful for detecting MPT infection.

Keyword

Mycobacteium avium subsp. paratuberculosis; 85 A; 85 B; 85 C; 35-kDa; Superoxide dismutase; Sensitivity; Specificity; ELISA; ROC curve analysis

MeSH Terms

Animals
Antibodies, Bacterial/*immunology
Antibody Formation/immunology
Antibody Specificity/immunology
Antigens, Bacterial/*immunology
Blotting, Western
Cattle
Cloning, Molecular
Electrophoresis, Polyacrylamide Gel
Enzyme-Linked Immunosorbent Assay/veterinary
Molecular Weight
Mycobacterium paratuberculosis/*immunology
Paratuberculosis/*diagnosis/microbiology
Protein Biosynthesis
Recombinant Fusion Proteins/*immunology
Serologic Tests
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