Biotechnology and Disease Resistance in Fish2

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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
    • 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 aquaculture.
    • 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 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 on 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.
   • Its efficiency exists for a longer duration with
     one or more treatments.
   • No toxic side effects and healthy fish have
     better growth performance.
   • No accumulation of toxic residues.
   • Pathogen will not develop resistance.
   • No environmental impact.
VACCINES                    SPECIES              DISEASE

Yersinia ruckeri Bacterin   Salmonids            red-mouth disease)

Vibrio                      Salmonids            Vibriosis
salmonicida Bacterin

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

Edwardsiella                Catfish              Enteric septicaemia
ictaluri Bacterin

Spring viraemia of carp     Common carp          Spring viraemia of carp

Biofilm and free-cell       Indian major carps   Dropsy
vaccines ofAeromonas
Vaccine delivery system
   • There are three methods of vaccination in
   • 1. Injection delivery system.
   • 2. Immersion delivery system.
   • 3. Oral delivery system.
    • 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.
    • Does the problem actually have a bacterial
    • Are the bacteria involved sensitive to the
      antibiotic chosen?
    • Are the proper dosage and treatment
      intervals being used?
    • Have other contributing stresses been
      removed or reduced?
Major Routes of Administration

   • Injection

   • Mixed in food

   • Bath treatments
List of Antibiotics
    • Erythromycin is most effective against
      gram-positive bacteria.
    • penicillin, amoxicillin, and ampicillin, are
      most effective against gram-positive bacteria.
    • 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.
   • Transgenesis may be defined as the introduction of
     exogenous gene / DNA into host genome resulting in
     its stable maintenance, transmission and expression.
   • The technology offers an excellent opportunity for
     modifying or improving the genetic traits of
     commercially important fishes.
   • The first transgenic fish was produced Zhu (1985) in
   • To realize the full potential of the transgenic fish
     technology in aquaculture, several important
     scientific break through are required.
   • include
   • more efficient technologies for mass gene transfer
   • targeted gene transfer technologies such as
     embryonic stem cell gene transfer
   • suitable promoters to direct the expression of
     transgenes at optimal levels during the desired
     developmental stages
   • identified genes of desireable traits for aquaculture
     and other applications
   • 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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