103
Disease Control
Slaughter of Infected Stock Evidence from Iceland has revealed that the culling
of infected Atlantic salmon brood stock led to a reduction in the incidence of BKD
(Gudmundsdóttir et al. 2000 ). At the start of the programme the incidence of infection was reported as ~35 % of the broodstock on two ranch sites, but after a few
years of adopting the programme of culling, the incidence fell to <2 %
(Gudmundsdóttir et al. 2000 ).
Disease Resistant Fish Work has pointed to some strains of fi sh which are resistant to BKD (Suzumoto et al. 1977 ; Winter et al. 1979 ; Withler and Evelyn 1990 )
and selective breeding enhance resistance to ERM and RTFS (Henryon et al. 2005 ).
Studying comparative resistance to BKD in three juvenile coho salmon and steelhead trout strains (transferrin genotypes AA, AC and CC), it was found that the AA
genotype was the most susceptible to BKD, whereas the CC genotype was the most
resistant. Withler and Evelyn ( 1990 ) found a variation in resistance to BKD in two
strains of coho salmon from British Columbia, Canada. In particular, survival was
greater and the time to death was longer in juvenile animals from the Kitimat River
strain than from the Robertson Creek strain.
Vaccine Development There is evidence that under some conditions, renibacteria
elicit a humoral and innate immune response in fi sh (Sanders et al. 1978 ; Young and
Chapman 1978 ; Bruno 1987 ; Jansson and Ljungberg 1998 ; Jansson et al. 2003 ), for
example directed to metalloprotease and haemolysin (Grayson et al. 2001 ).
However, it is apparent that early exposure to the p57 antigen can lead to long term
immunosuppression (Brown et al. 1996 ). Conversely, removal of the p57 antigen
from the surface of renibacterial cells has led to enhanced immunogenicity (Wood
and Kaattari 1996 ). Administration of experimental vaccines prepared in FCA
resulted in the development of humoral antibody (Evelyn 1971 ; Baudin- Laurençin
et al. 1977 ). Evelyn (1971) detected antibodies in immature sockeye salmon at least
16 months after an i.p. injection with a heat-killed suspension in adjuvant. A second
injection after 13 months resulted in a sharp increase in antibody titre from 1:2560
(after the fi rst injection) to 1:10247. The protective ability of vaccines is, however,
questionable (Sakai et al. 1989c , 1993 ). Sakai et al. ( 1993 ) compared formalised
(RPS = 10–23.8 %), heat-killed, pH lysed (RPS = 35–36 %) and UV killed
(RPS = 25 %) cells of Ren. salmoninarum and streptococci, and concluded that protection of rainbow trout did not develop. Also, Baudin-Laurençin et al. ( 1977 ) found
no protective effect after injection of coho salmon with cells contained in
FCA. Paterson et al. ( 1981 ), using a similar vaccine in Atlantic salmon, reported
high agglutination titres and a reduced incidence of BKD lesions after 1 year, but
FAT revealed the same number of bacteria in both vaccinated and unvaccinated
(control) fi sh (Paterson et al. 1981 ). Although McCarthy et al. ( 1984 ) reported optimistically that their vaccine worked in fi sh, close scrutiny of the data suggests success comparable to that of Paterson et al. ( 1981 ). McCarthy and co- workers used a
Renibacterium salmoninarum
Disease Control
Slaughter of Infected Stock Evidence from Iceland has revealed that the culling
of infected Atlantic salmon brood stock led to a reduction in the incidence of BKD
(Gudmundsdóttir et al. 2000 ). At the start of the programme the incidence of infection was reported as ~35 % of the broodstock on two ranch sites, but after a few
years of adopting the programme of culling, the incidence fell to <2 %
(Gudmundsdóttir et al. 2000 ).
Disease Resistant Fish Work has pointed to some strains of fi sh which are resistant to BKD (Suzumoto et al. 1977 ; Winter et al. 1979 ; Withler and Evelyn 1990 )
and selective breeding enhance resistance to ERM and RTFS (Henryon et al. 2005 ).
Studying comparative resistance to BKD in three juvenile coho salmon and steelhead trout strains (transferrin genotypes AA, AC and CC), it was found that the AA
genotype was the most susceptible to BKD, whereas the CC genotype was the most
resistant. Withler and Evelyn ( 1990 ) found a variation in resistance to BKD in two
strains of coho salmon from British Columbia, Canada. In particular, survival was
greater and the time to death was longer in juvenile animals from the Kitimat River
strain than from the Robertson Creek strain.
Vaccine Development There is evidence that under some conditions, renibacteria
elicit a humoral and innate immune response in fi sh (Sanders et al. 1978 ; Young and
Chapman 1978 ; Bruno 1987 ; Jansson and Ljungberg 1998 ; Jansson et al. 2003 ), for
example directed to metalloprotease and haemolysin (Grayson et al. 2001 ).
However, it is apparent that early exposure to the p57 antigen can lead to long term
immunosuppression (Brown et al. 1996 ). Conversely, removal of the p57 antigen
from the surface of renibacterial cells has led to enhanced immunogenicity (Wood
and Kaattari 1996 ). Administration of experimental vaccines prepared in FCA
resulted in the development of humoral antibody (Evelyn 1971 ; Baudin- Laurençin
et al. 1977 ). Evelyn (1971) detected antibodies in immature sockeye salmon at least
16 months after an i.p. injection with a heat-killed suspension in adjuvant. A second
injection after 13 months resulted in a sharp increase in antibody titre from 1:2560
(after the fi rst injection) to 1:10247. The protective ability of vaccines is, however,
questionable (Sakai et al. 1989c , 1993 ). Sakai et al. ( 1993 ) compared formalised
(RPS = 10–23.8 %), heat-killed, pH lysed (RPS = 35–36 %) and UV killed
(RPS = 25 %) cells of Ren. salmoninarum and streptococci, and concluded that protection of rainbow trout did not develop. Also, Baudin-Laurençin et al. ( 1977 ) found
no protective effect after injection of coho salmon with cells contained in
FCA. Paterson et al. ( 1981 ), using a similar vaccine in Atlantic salmon, reported
high agglutination titres and a reduced incidence of BKD lesions after 1 year, but
FAT revealed the same number of bacteria in both vaccinated and unvaccinated
(control) fi sh (Paterson et al. 1981 ). Although McCarthy et al. ( 1984 ) reported optimistically that their vaccine worked in fi sh, close scrutiny of the data suggests success comparable to that of Paterson et al. ( 1981 ). McCarthy and co- workers used a
Renibacterium salmoninarum