title: Resistance to serum killing may contribute to differences in the abilities of capsulate and non-capsulated isolates of lactococcus garvieae to cause disease in rainbow trout (Oncorhynchus mykiss L.).
abstract: Three capsulated and two non-capsulated isolates of Lactococcus garvieae were investigated in terms of their wall proteins, virulence and interactions with rainbow trout immunoglobulin (Ig). All isolates were similar in integral membrane protein profile, and all were able to bind non-immune rainbow trout Ig, although different proteins appeared to be involved in Ig binding. However, whilst capsulated isolates were highly virulent, non-capsulated isolates were avirulent. This appeared to correlate with susceptibility of the non-capsulated isolates to rainbow trout normal serum. In contrast, the capsulated isolates were resistant to both normal and immune serum killing. In spite of this, passive immunisation of rainbow trout with specific anti-serum to L. garvieae was able to protect against challenge by capsulated isolates of L. garvieae. This suggests the antibody may have some other role in protection against disease caused by this important Gram-positive bacterial fish pathogen.
authors.affiliation: The Marine Laboratory, Aberdeen, Scotland, UK. abarnes@aeromonas.demon.co.uk
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Barnes
authors.forename: Céline
authors.initials: C
authors.lastname: Guyot
authors.forename: Bjarne G
authors.initials: BG
authors.lastname: Hanse
authors.forename: Kevin
authors.initials: K
authors.lastname: Mackenzie
authors.forename: Michael T
authors.initials: MT
authors.lastname: Horn
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Ellis
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D016667:Bacterial Capsules / Q000276:immunology* / Q000494:pharmacology; D001770:Blood Bactericidal Activity; D002473:Cell Wall / Q000737:chemistry; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D016908:Gram-Positive Bacterial Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D007106:Immune Sera / Q000276:immunology; D007113:Immunity, Innate; D007116:Immunization, Passive / Q000662:veterinary; D007136:Immunoglobulins / Q000032:analysis / Q000276:immunology; D017045:Lactococcus / Q000737:chemistry / Q000276:immunology / Q000472:pathogenicity*; D017686:Oncorhynchus mykiss; D014774:Virulence
chemical_list: D000907:Antibodies, Bacterial; D007106:Immune Sera; D007136:Immunoglobulins