Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

Mark C. Healey


Mark C. Healey


Reed P. Warren


Bill B. Barnett


Ross A. Smart


The purpose of this study was to characterize phenotypically Actinobacillus and Actinobacillus-like species cultured from ram lambs with epididymitis (lamb epididymitis), so as to better understand the species and strains of Actinobacillus responsible for causing the disease. Two American Type Culture Collection (ATCC) type species of Actinobacillus (A actinomycetemcomitans and A seminis) and 24 field isolates were tested in this study. The field isolates were cultured from either lesions or semen of ram lambs with clinical epididymitis and had been identified as members of the genus Actinobacillus, based on cultural and morphological criteria. When analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), these field isolates could be divided into 4 groups, based on the similarities and differences in the protein profiles.

A panel of 13 MoAbs directed against 3 distinct proteins extracted from 1 field isolate (As8C) were also used in the enzymelinked immunosorbent assay (ELISA), flow cytometry, and bacterial agglutination to screen these field isolates. Specificity of the MoAbs for the 3 proteins was confirmed by the enzyme-linked immunoelectrotransfer blot (EITB) technique.

Bacterial field isolates were also divided into 3 groups by the ELISA results, based on their different reaction intensities. Data generated by the flow cytometry, namely peak channel, mean value, and percent labeled cells, suggested that these field isolates could be divided into 2 groups. However, with the unique reaction pattern for each MoAb, the flow cytometry data suggested the possibility of preparing a bank of figures as a standardized reference to identify additional isolates belonging to the genus of Actinobacillus. Bacterial agglutination of some isolates was noted using hyperimmune mouse serum (HMS), but not using MoAbs. These data suggested that bacterial field isolates cultured from epididymal lesions of affected lambs were considered to be in the same group as the 2 ATCC-type species of Actinobacillus . Further studies will be required in determining whether A seminis or some other species of Actinobacillus is the primary pathogen responsible for lamb epididymitis.