378
Addressing the question of the interval necessary for the onset and duration of
immunity to develop, Johnson et al. ( 1982a ) reported that a 5 s immersion in a vaccine suspension was suffi cient to induce protection within 5 days at 18 °C, or 10
days at 10 °C. The minimum size of salmonids necessary for maximal protection
was estimated to be in the range of 1.0–2.5 g. In fact, these authors concluded that
protection was correlated with size of the fi sh, and not their age. Thus with 1.0, 2.0
and 4.0 g fi sh, immunity lasted for approximately 4, 6 and 12 months, respectively
(Johnson and Amend 1983b ). However, the water temperature was important, with
15 °C being completely effective but not so 5 or 25 °C (Raida and Buchmann 2008 ).
There was some variation in results between species, with coho salmon and sockeye
salmon retaining immunity for longer than pink salmon. Lamers and Muiswinkel
( 1984 ) concluded that a secondary immune response occurred as long as 7 months
after primary contact with the antigen, indicating the presence of a fairly long-lived
memory. Cossarini-Dunier ( 1986 ) found protection lasted for 445 days after intraperitoneal injection of a formalised culture which was suspended in saline or oily
adjuvant. Thus, after challenge, 88.5 % of the controls died but only a few vaccinates. Interestingly, booster vaccination using 1: 100, 1: 1000 and 1: 2000 dilutions
of inactivated whole cell vaccine with 1 h or 2 h exposure resulted in higher and
longer protection although the typical 30 s in a 1:10 dilution was better (Chettri
et al. 2015 ).
The commercial immersion vaccines were less successful at controlling the new
biogroup (RPS = 47 % compared to 95 % for the Hagerman strain). This prompted
an approach to supplement a current commercial vaccine with formalised whole
cells of the new biogroup (RPS = 56 % compared to 97 % for the Hagerman strain)
or by using an autologous vaccine comprised exclusively of formalin-inactivated
cells of the new biogroup (RPS = 76 % compared to 58 % for the Hagerman strain)
(Austin et al. 2005 ). A parallel situation occurred with Atlantic salmon culture in
Tasmania whereby the standard ERM vaccine lost effectiveness, and led to an
improved product involving the trypsinisation of the component culture to expose
the O-antigen and thereby improving antigenicity. The end result was improved
protection [the RPS increased from 37 % to 55.6 %] (Costa et al. 2011 ). A new commercial vaccine, which contains antigens of the Hagerman strain and the new biogroup, has been marketed, and its use documented to protect rainbow trout against
biogroup 1 and 2 (Deshmukh et al. 2012 ). A comparison of commercial vaccines,
one of which contained biogroup 1 and the second that was formulated with both
biogroups, revealed better protection for rainbow trout with the latter 4 and 6-months
after the standard 30 s immersion (Deshmukh et al. 2012 ).
Use of non-adjuvanted fl agellin as a sub-unit vaccine in the native and recombinant form resulted in protection from challenge with biotype 1 and biotype 2 cultures of Y. ruckeri . Moreover, there was evidence of protection against pathogens,
e.g. Aer. salmonicida (Scott et al. 2013 ).
Immunostimulants/Dietary Supplements Vigneulle and Gérard ( 1986 ) reported
that 48 000 IU/kg, 8 650 mg/kg and 500 mg/kg of vitamin A, C and E for 5 days
respectively enhanced resistance to ERM.
6 Enterobacteriaceae Representatives
Addressing the question of the interval necessary for the onset and duration of
immunity to develop, Johnson et al. ( 1982a ) reported that a 5 s immersion in a vaccine suspension was suffi cient to induce protection within 5 days at 18 °C, or 10
days at 10 °C. The minimum size of salmonids necessary for maximal protection
was estimated to be in the range of 1.0–2.5 g. In fact, these authors concluded that
protection was correlated with size of the fi sh, and not their age. Thus with 1.0, 2.0
and 4.0 g fi sh, immunity lasted for approximately 4, 6 and 12 months, respectively
(Johnson and Amend 1983b ). However, the water temperature was important, with
15 °C being completely effective but not so 5 or 25 °C (Raida and Buchmann 2008 ).
There was some variation in results between species, with coho salmon and sockeye
salmon retaining immunity for longer than pink salmon. Lamers and Muiswinkel
( 1984 ) concluded that a secondary immune response occurred as long as 7 months
after primary contact with the antigen, indicating the presence of a fairly long-lived
memory. Cossarini-Dunier ( 1986 ) found protection lasted for 445 days after intraperitoneal injection of a formalised culture which was suspended in saline or oily
adjuvant. Thus, after challenge, 88.5 % of the controls died but only a few vaccinates. Interestingly, booster vaccination using 1: 100, 1: 1000 and 1: 2000 dilutions
of inactivated whole cell vaccine with 1 h or 2 h exposure resulted in higher and
longer protection although the typical 30 s in a 1:10 dilution was better (Chettri
et al. 2015 ).
The commercial immersion vaccines were less successful at controlling the new
biogroup (RPS = 47 % compared to 95 % for the Hagerman strain). This prompted
an approach to supplement a current commercial vaccine with formalised whole
cells of the new biogroup (RPS = 56 % compared to 97 % for the Hagerman strain)
or by using an autologous vaccine comprised exclusively of formalin-inactivated
cells of the new biogroup (RPS = 76 % compared to 58 % for the Hagerman strain)
(Austin et al. 2005 ). A parallel situation occurred with Atlantic salmon culture in
Tasmania whereby the standard ERM vaccine lost effectiveness, and led to an
improved product involving the trypsinisation of the component culture to expose
the O-antigen and thereby improving antigenicity. The end result was improved
protection [the RPS increased from 37 % to 55.6 %] (Costa et al. 2011 ). A new commercial vaccine, which contains antigens of the Hagerman strain and the new biogroup, has been marketed, and its use documented to protect rainbow trout against
biogroup 1 and 2 (Deshmukh et al. 2012 ). A comparison of commercial vaccines,
one of which contained biogroup 1 and the second that was formulated with both
biogroups, revealed better protection for rainbow trout with the latter 4 and 6-months
after the standard 30 s immersion (Deshmukh et al. 2012 ).
Use of non-adjuvanted fl agellin as a sub-unit vaccine in the native and recombinant form resulted in protection from challenge with biotype 1 and biotype 2 cultures of Y. ruckeri . Moreover, there was evidence of protection against pathogens,
e.g. Aer. salmonicida (Scott et al. 2013 ).
Immunostimulants/Dietary Supplements Vigneulle and Gérard ( 1986 ) reported
that 48 000 IU/kg, 8 650 mg/kg and 500 mg/kg of vitamin A, C and E for 5 days
respectively enhanced resistance to ERM.
6 Enterobacteriaceae Representatives