title: Induced resistance to infection of lobsters Homarus americanus by Aerococcus viridans (var.) homari, the bacterium causing gaffkemia.
abstract: A vaccine composed of steam sterilized (autoclaved) cells of a virulent strain of Aerococcus viridans (var.) homari was effective in protecting lobsters Homarus americanus against gaffkemia. At 15 degrees C the heat-killed vaccines (HKV) at concentrations between 1 and 5 x 10(7) particles kg(-1) lobster body wt induced maximal protection in induction periods ranging from 7 to 11 d. Protection was substantial over the course of a 30 d post-induction trial period. Spring-caught lobsters (i.e. those more fully rehabilitated following ecdysis) gained more protection (LD50 = 1.9 x 10(4)) from the vaccination than did those caught in the late fall-early winter period (lobsters that were not yet fully recovered from ecdysis) (LD50 = 3.2 x 10(3)). The protection offered by the HK vaccine was comparable to that induced by a vaccine produced by incubating the pathogen with low concentrations (2 pg ml(-1)) of the antibiotic vancomycin. The bacterins produced by both methods exhibited similar new properties: (1) agglutination at low titres by lobster hemolymph serum, suggesting an impaired capsule layer, and (2) increased permeability to the large Alcian Blue molecule. With both vaccines, the protection may be a direct result of increased exposure to intact bacterial cell structures by the lobster defences, an exposure which otherwise would be prevented by an intact capsule.
authors.affiliation: Science Branch, Department of Fisheries and Oceans, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada. stewartje@mar.dfo-mpo.gc.ca
authors.forename: James E
authors.initials: JE
authors.lastname: Stewart
authors.forename: B
authors.initials: B
authors.lastname: Arie
authors.forename: L J
authors.initials: LJ
authors.lastname: Marks
mesh_terms: D000372:Agglutination Tests; D000423:Alcian Blue; D000818:Animals; D017756:Aquaculture / Q000379:methods; D001428:Bacterial Vaccines / Q000276:immunology*; D007113:Immunity, Innate / Q000276:immunology*; D008121:Nephropidae / Q000276:immunology* / Q000382:microbiology*; D010587:Phagocytosis / Q000276:immunology; D013289:Streptococcaceae / Q000276:immunology*; D013997:Time Factors
chemical_list: D001428:Bacterial Vaccines; D000423:Alcian Blue