540
This compares with the work of Horne et al. ( 1982 ), who reported mortalities of:
unvaccinated controls 100 %
oral-vaccinated fi sh 94 %
immersion vaccinated group 53 %
group vaccinated by injection 7 %
In a detailed examination of the effects of oral administration of formalininactivated vaccines in chinook salmon, Fryer et al. ( 1978 ) noted that maximal protection followed the feeding of 2 mg of dried vaccine/g of food for 15 days at
temperatures even as low as 3.9 °C. An important corollary was the observation that
longer feeding regimes did not result in enhanced protection. This should be considered if prolonged durations of vaccination, via the oral route, are advocated. The
reason for the apparently discouraging results with oral vaccination regimes may
refl ect the breakdown of vaccine inside the digestive tract (Johnson and Amend
1983 ). To resolve this problem, Johnson and Amend ( 1983 ) incorporated a vaccine
into gelatin, and applied it orally and anally in attempts to overcome digestion in the
stomach and intestine. Encouraging results were obtained, particularly in regard to
anal application, in which mortalities following challenge were:
unvaccinated controls 97 %
vaccine (minus gelatin) applied orally 35 %
vaccine (with gelatin) applied orally 69 %
vaccine (minus gelatin) applied anally 37 %
vaccine (with gelatin) applied anally 7 %
Similar encouraging data were published by Dec et al. ( 1990 ). These workers
used a commercial vaccine (produced by Rhône-Merieux), which was administered
orally to turbot and sea bass. Following challenge 28 days later, the following mortalities were reported:
oral-vaccinated sea bass 11.3 %
unvaccinated sea bass 40.9 %
oral vaccinated turbot 19.2 %
unvaccinated turbot 65.4 %
Incorporation of vaccine with natural food, i.e. plankton, has shown promise
with ayu (Kawai et al. 1989 ). Thus in one set of experiments, 7.6 % of the vaccinates
died, compared to 35.8 % of the controls.
Noting that a pJM1-plasmid-free culture was comparatively attenuated, Shao
et al. ( 2005 ) used a plasmid-free culture, coined MVAV6201, as a live vaccine to
deliver two recombinant proteins, GFP-HlyAs [HlyA = Esch. coli α-haemolysin]
and AngE-HlyAs, which were fused with the α-haemolysin secretion signal and
expressed from the secretion vector pMOhlyl. Almost 70 % and ~300 μg/l of GFPHlyAs and AngE-HlyAs were secreted into the culture supernatant, respectively
(Shao et al. 2005 ).
10 Vibrios
This compares with the work of Horne et al. ( 1982 ), who reported mortalities of:
unvaccinated controls 100 %
oral-vaccinated fi sh 94 %
immersion vaccinated group 53 %
group vaccinated by injection 7 %
In a detailed examination of the effects of oral administration of formalininactivated vaccines in chinook salmon, Fryer et al. ( 1978 ) noted that maximal protection followed the feeding of 2 mg of dried vaccine/g of food for 15 days at
temperatures even as low as 3.9 °C. An important corollary was the observation that
longer feeding regimes did not result in enhanced protection. This should be considered if prolonged durations of vaccination, via the oral route, are advocated. The
reason for the apparently discouraging results with oral vaccination regimes may
refl ect the breakdown of vaccine inside the digestive tract (Johnson and Amend
1983 ). To resolve this problem, Johnson and Amend ( 1983 ) incorporated a vaccine
into gelatin, and applied it orally and anally in attempts to overcome digestion in the
stomach and intestine. Encouraging results were obtained, particularly in regard to
anal application, in which mortalities following challenge were:
unvaccinated controls 97 %
vaccine (minus gelatin) applied orally 35 %
vaccine (with gelatin) applied orally 69 %
vaccine (minus gelatin) applied anally 37 %
vaccine (with gelatin) applied anally 7 %
Similar encouraging data were published by Dec et al. ( 1990 ). These workers
used a commercial vaccine (produced by Rhône-Merieux), which was administered
orally to turbot and sea bass. Following challenge 28 days later, the following mortalities were reported:
oral-vaccinated sea bass 11.3 %
unvaccinated sea bass 40.9 %
oral vaccinated turbot 19.2 %
unvaccinated turbot 65.4 %
Incorporation of vaccine with natural food, i.e. plankton, has shown promise
with ayu (Kawai et al. 1989 ). Thus in one set of experiments, 7.6 % of the vaccinates
died, compared to 35.8 % of the controls.
Noting that a pJM1-plasmid-free culture was comparatively attenuated, Shao
et al. ( 2005 ) used a plasmid-free culture, coined MVAV6201, as a live vaccine to
deliver two recombinant proteins, GFP-HlyAs [HlyA = Esch. coli α-haemolysin]
and AngE-HlyAs, which were fused with the α-haemolysin secretion signal and
expressed from the secretion vector pMOhlyl. Almost 70 % and ~300 μg/l of GFPHlyAs and AngE-HlyAs were secreted into the culture supernatant, respectively
(Shao et al. 2005 ).
10 Vibrios