Immunoassay Comparison of Haplosporidan Spores from Teredo navalis and Haplosporidium nelsoni Spores from Crassostrea virginica

Spores of a haplosporidan infecting Teredo navalis Linnaeus have been described as morphologically indistinguishable from spores of Haplosporidium nelsoni . To test the hypothesis that these organisms are conspecific, a colloidal gold immunoassay was used to compare antigenic characteristics of the spores from both hosts. Rabbit antibody to formalin-fixed spores from T. navalis was tested against paraffin sections of Crassostrea virginica infected with spores of H. nelsoni and against paraffin sections of infected 7". navalis . Application of primary antibody was followed by addition of affinity purified goat anti-rabbit IgG coaled on 5-nm colloidal gold particles. The reaction was enhanced by precipitation of metallic silver; a positive reaction appeared as a dark brown to black signal at the site of each antigen-antibody complex. Haplosporidium nelsoni spores did not react when assayed with the antibody made to spores from T. navalis . Spores from infected T. navalis tissue reacted positively with rabbit antibody. This result indicates that the spores from the 2 hosts are antigenicaliy distinct and suggests that they are different species.