BINDING SPECIFICITIES OF MONOCLONAL AND POLYCLONAL ANTIBODIES TO THE PROTOZOAN OYSTER PATHOGEN PERKINSUS-MARINUS

In an effort to develop direct detection methods for Perkinsus marinus cells in host tissue and environmental samples, the production of both mono- and polyclonal antibodies specific for this apicomplexan oyster pathogen was attempted. A particulate hypnospore immunogen was isolated from infected oyster hemolymph following incubation in Ray's fluid thioglycollate medium. Polyclonal antisera produced in both mice and rabbits following immunization with this preparation exhibited high antibody titers for pathogen cell epitopes, but not for host oyster tissue epitopes. At least some antibodies to hypnospore antigenic determinants recognized common epitopes on trophozoite cells in infected oyster tissues, as well as on zoospores and other proliferative cells produced by incubation of infected oyster hemolymph in sterile seawater. Polyclonal antibodies also recognized a diffusable, noncellular substance present in host oyster tissues in areas surrounding focal lesions. Rabbit polyclonal antibodies did not recognize 2 Dermocystidium species infecting salmonid fishes or Haplosporidium nelsoni infecting eastern oysters Crassostrea virginica. These antibodies did recognize many, but not all, Perkinsus species infecting selected molluscan hosts worldwide. Monoclonal antibodies produced to date apparently recognize epitopes unique to the hypnospore immunogen.