Introduction:  Novel compositions are disclosed for use in the treatment or diagnosis of bovine pasteurellosis, commonly referred to as Shipping Fever.  Cell-free Pasteurella haemolytica supernatants are employed to provide individual antigen compositions, identified through reaction with sera from naturally-infected or convalescent cattle.  In particular, at least seven individual P. haemolytica antigen groups were recognized in cell-free culture supernatants. Purified P. haemolytica supernatant, formulated in a suitable pharmaceutical vaccine composition is shown to elicit a specific immune response, in both cows and rabbits, directed against the individual immunoreactive P. haemolytica polypeptides identified.  Also disclosed are novel recombinant cells, plasmids and bacteriophage which include transcriptionally active P. haemolytica antigen genes.  Recombinant clones are similarly selected to be reactive with naturally-infected antisera. Examples, and further disclosure, are also provided which demonstrate the utility of a presently disclosed antibody and antigen compositions in immuno-detection of both antigens and antibodies in various biological samples.