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Monoclonal antibody in the identification of Haemophilus somnus
M S Thomson1, L H Lauerman, G R Wilt
1Department of Pathobiology, College of Veterinary Medicine, Auburn University, AL 36849.
Abstract:
Electrophoretic comparisons of outer membrane proteins of Haemophilus somnus isolates revealed 2 major protein bands (46 and 14 kilodaltons [kD]) common to all isolates tested. A monoclonal antibody raised against H. somnus reacted to the 46-kD band. Coagglutination tests were performed using a monoclonal antibody coagglutination assay. The monoclonal reagent was produced by incubating Cowan strain Staphylococcus aureus suspension, used as a source of crude protein A, with mouse ascitic fluid monoclonal antibody or goat anti-H. somnus hyperimmune serum. Bacteria to be tested were suspended at a concentration of 4.5 x 10(9) cells/ml. The coagglutination test was performed by the addition of 50 microliters of the monoclonal reagent to 50 microliters of the bacterial suspension on a glass plate and manual rotation for 2-3 minutes. The coagglutination assay using Cowan strain Staphylococcus aureus protein A, coupled with the monoclonal antibody, agglutinated 10 different H. somnus isolates. The antibody reagent did not coagglutinate with Actinobacillus suis, A. equuli, Pasteurella haemolytica, P. multocida, or P. pneumotropica under similar test conditions.
Insights
A new coagglutination test using a monoclonal antibody effectively identified Haemophilus somnus (H. somnus) isolates. This diagnostic method targets a specific 46-kD outer membrane protein, showing high specificity against related bacteria.
Area of Science:
- Veterinary Microbiology
- Immunodiagnostics
- Bacterial Pathogenesis
Background:
- Haemophilus somnus is a significant pathogen in livestock, causing various diseases.
- Accurate and rapid identification of H. somnus is crucial for effective disease management.
- Current diagnostic methods may lack specificity or require extensive laboratory procedures.
Purpose of the Study:
- To develop and evaluate a monoclonal antibody-based coagglutination assay for the rapid identification of Haemophilus somnus.
- To characterize the outer membrane proteins of H. somnus isolates.
- To assess the specificity of the developed assay against other bacterial species.
Main Methods:
- Outer membrane proteins of H. somnus isolates were analyzed using electrophoretic techniques.
- A monoclonal antibody was generated against H. somnus, specifically targeting a 46-kilodalton (kD) protein.
- A coagglutination assay was developed by coupling the monoclonal antibody with Staphylococcus aureus (Cowan strain) protein A.
Main Results:
- Electrophoresis revealed two common outer membrane protein bands (46-kD and 14-kD) in all H. somnus isolates.
- The monoclonal antibody specifically reacted with the 46-kD protein band.
- The developed coagglutination assay successfully agglutinated 10 different H. somnus isolates.
- The assay demonstrated high specificity, showing no agglutination with tested species including Actinobacillus suis, Actinobacillus equuli, Pasteurella haemolytica, Pasteurella multocida, and Pasteurella pneumotropica.
Conclusions:
- A monoclonal antibody targeting a 46-kD outer membrane protein of H. somnus is effective for bacterial identification.
- The monoclonal antibody coagglutination assay provides a rapid, specific, and potentially valuable diagnostic tool for H. somnus.
- This assay offers a promising alternative for the timely diagnosis of H. somnus infections in veterinary settings.