Characterization of antigen purified from type 3 strains of Pasteurella multocida and its use for an enzyme-linked immunosorbent assay.

Surface antigens were purified from a type 3, 4 rabbit isolate of Pasteurella multocida designated as R11146. Two protein peaks were obtained by gel filtration with Sephadex G-200 from crude saline extract. Major antigenic activity was detected in the first peak. The first peak was absorbed onto DEAE-cellulose and eluted by a linear gradient of NaCl. Four fractions eluted from the column contained a single antigen which was identical to an antigen purified from another type 3 strain, P-1059. Also, they uniformly contained two protein species of molecular weights of 44,000 and 25,500. Six Pasteurella-free rabbits were infected intranasally with R11146 isolate and antibody response was determined by an enzyme-linked immunosorbent assay (ELISA) with the use of an antigen purified from P-1059 strain. Serum samples from the infected rabbits showed ELISA titers at the plateau stage by 21 or 28 days post-inoculation. Highest titers ranged from 1:15,000 to 1:16,000, while all the preinoculation sera had titers lower than 1:10. The high titers generally persisted for longer than 98 days after the infection. These results indicate that ELISA using a purified type 3 antigen is useful to detect P. multocida infection in rabbits by a type 3-related strain.