Antigen recognition by rainbow trout (Oncorhynchus mykiss) of whole cell proteins expressed by Lactococcus garvieae when obtained directly from fish and under iron limited culture conditions.
Infection by Lactococcus garvieae has become a widely recognised problem associated with intensively cultured fish. Long-term control of fish infections may be possible by vaccination providing a suitable and efficacious epitope is expressed during production of cells used for vaccine preparation. The identification of novel vaccine candidates must, therefore, consider how the host species recognises and responds to bacterial cell components. L. garvieae was cultured in iron deficient, limited and haem iron enriched media and the whole cell proteins expressed under these conditions were compared with those expressed in bacteria extracted with Percoll gradients directly from spleen tissue of infected rainbow trout (Oncorhynchus mykiss). SDS-PAGE of the cell proteins showed the existence of several different electropherotypes according to the iron status of the culture media. Only minor differences in cell protein profile were detected in bacteria obtained directly from fish spleens, but when the electropherograms were analysed by Western blots using L. garvieae hyperimmune fish sera, several proteins could be identified that were expressed only when L. garvieae was growing in vivo. Siderophore could be detected in culture supernatant of iron deficient, limited and haem iron enriched media but not in media with higher nutrient concentrations. The siderophore could not be identified as a type of catechol or hydroxymate. Rainbow trout recognise proteins in the range of approximately 50-80 kDa for bacterial cells obtained without subculture from infected fish and culture conditions can influence protein profiles for this pathogen.
Schmidtke
L M
LM
National Wine and Grape Industry Centre, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia. lschmistke@csu.edu.au
Carson
J
J
D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D017756:Aquaculture; D001426:Bacterial Proteins / Q000276:immunology*; D015153:Blotting, Western / Q000662:veterinary; D005393:Fish Diseases / Q000276:immunology / Q000382:microbiology*; D007501:Iron / Q000276:immunology / Q000378:metabolism*; D017045:Lactococcus / Q000276:immunology* / Q000378:metabolism; D017686:Oncorhynchus mykiss / Q000276:immunology*; D017262:Siderophores / Q000276:immunology / Q000378:metabolism; D013154:Spleen / Q000382:microbiology
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D017262:Siderophores; D007501:Iron