biotechnology and disease resistance in fish

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					   Biotechnology and
Disease Resistance in Fish

         Waqas Ali
• Fish in culture are susceptible to a wide
  range of bacterial, viral, parasitic and
  fungal infections
• Biotechnology can have a direct positive
  impact on many of the main elements of
  fish health management
• Biotechnology provides powerful tools for
  the sustainable development of
• Genetic modification and biotechnology
  also holds potential to improve the quality
  and quantity of fish reared in aquaculture.
  The impact of biotechnology in
     fish health management
While considerable progress has been made in fish biotechnology
in Asia, the following aspects need to be further strengthened
(Guerrero, 1991):
 Genetic improvement of cultured fish for improved
 growth, disease resistance and adaptability to new
 farming systems.(i.e GIFT )
 . Production of vaccines and monoclonal antibodies for
 the prevention and control of bacterial and virus
 Development of drugs and other biotechnological
 products from marine organisms.
• The stress and disease in intensive fish
  culture have led to treatment with
  antibiotics and chemicals.
• regarding the pollution associated with
  chemical treatments, methods such as
  vaccination and the use of
  immunostimulants has developed.
• vaccine must provide long-term protection
  against the disease under the intensive
  rearing conditions
• The primary considerations for any
  successful vaccine for aquaculture are cost-
  effectiveness and safety.

• Most of the commercial vaccines
  presently available consist
  inactivated (killed) disease agents
• The majority of commercial vaccines
  are multivalent and target salmon
  and trout but there are expanding
  opportunities in the temperate and
  warm-water species found in the
  Asia–Pacific region.
   Importance of vaccination
• Vaccines are used to prevent a specific
  disease outbreak from occurring and are not
  a therapy.
• á Its efficiency exists for a longer
  duration with one or more treatments.
• á No toxic side effects and healthy fish
  have better growth performance.
• á No accumulation of toxic residues
• á Pathogen will not develop resistance.
• á Theoretically it can control any
  bacterial and viral disease.
• á No environmental impact.
VACCINES                         SPECIES              DISEASE

Yersinia ruckeri Bacterin        Salmonids            red-mouth disease)

Vibrio salmonicida Bacterin      Salmonids            Vibriosis

Koi herpes virus (KHV)           Koi carp             Koi herpes virus (KHV) disease

Edwardsiella ictaluri Bacterin   Catfish              Enteric septicaemia

Spring viraemia of carp virus    Common carp          Spring viraemia of carp

Biofilm and free-cell vaccines   Indian major carps   Dropsy
ofAeromonas hydrophila
        Use of Antibiotics

• Antibiotics are very useful additions
  to any fish-health manager's toolbox,
  but they are only tools and not
  'magic bullets.‘
• The ability of antibiotics to help
  eliminate a fish disease depends on a
  number of factor
• Antibiotics merely control the
  population growth of bacteria in a
  fish long enough for its immune
  system to eliminate them.
• 1) Does the problem actually have a
  bacterial component?
• 2) Are the bacteria involved sensitive
  to the antibiotic chosen?
• 3) Are the proper dosage and
  treatment intervals being used?
• 4) Have other contributing stresses
  been removed or reduced?
         Major Routes of
          of Antibiotics
• Injection
• Mixed in food
• Bath treatments
          List of Antibiotics
• Erythromycin is most effective against
  gram-positive bacteria
• including penicillin, amoxicillin, and
  ampicillin, are most effective against gram-
• Oxytetracycline and related antibiotics are
  considered broad-spectrum antibiotics
• Terramycin
• gentamicin, neomycin, kanamycin are very
  effective against gram-negative bacteria
• The sulfa drugs are also considered to be
  broad-spectrum antibiotics.
            Transgenic Fish

transgenics may be defined as the introduction of
exogenous gene / DNA into host genome resulting
   in its stable maintenance, transmission and
The technology offers an excellent opportunity for
   modifying or improving the genetic traits of
           commercially important fishers
 The first transgenic fish was produced Zhu et al.
                   (1985) in China,
 To realize the full potential of the transgenic fish
  technology in aquaculture, several important
      scientific break Ð through are required.
• There include
• more efficient technologies for mass gene
  transfer (ii) targeted gene transfer
  technologies such as embryonic stem cell
  gene transfer (iii) suitable promoters to
  direct the expression of transgenes at
  optimal levels during the desired
  developmental stages (iv) identified genes
  of desireable traits for aquaculture and
  other applications (v) informations on the
  physiological, nutritional, immunological
  and environmental factors that maximize
  the performance of the transgenics of the
  transgenics and (vi) safety and
  environmental impacts of transgenic fish.
• Biotechnological research and
  development are growing at a very
  fast rate. The biotechnology has
  assumed greatest importance in
  recent years in the development of
  fisheries, agriculture and human
  health.The application of
  biotechnology in the fisheries sector
  is a relatively recent practice.
  Neverthless,it is a promising area to
  enhance fish production.

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