179
of cytosolic calcium homeostasis initiating the activation particularly of calpain-2,
which leads to caspase-3 mediated apoptosis (Banerjee et al. 2012 ).
Clearly, the evidence indicates the involvement of both endo- and exo-toxins in
the pathogenesis of Aer hydrophila infections. It still remains for further work to
elucidate the precise mechanism of action.
Evidence from Molecular Analyses
By comparing a virulent and avirulent culture, suppression subtractive hybridization (SSH) was used to identify genetic differences, with the results highlighting 69
genomic regions absent from the latter (Zhang et al. 2000 ). Genes considered to
represent known virulence attributes included haemolysin, histone-like protein, oligoprotease A, OMP and multi-drug resistance protein. Other genes encoded synthesis of O-antigen (Zhang et al. 2000 ).
Quorum Sensing
Quorum sensing has been linked to virulence of Aer. hydrophila in burbot ( Lota
lota ). Using quorum sensing mutants – involving N-(butyryl)-L-homoserine lactone
production and receptor mutants – less mortalities developed compared to use of the
wild type culture. Moreover, virulence was restored in the mutants by the addition
of N-butyryl-L-homoserine lactone. Conversely, the addition of quorum sensing
inhibitors protected the burbot larvae from the virulent organism (Natrah et al.
2012 ).
Disease Control
Disease Resistant Fish
The differential resistance of four strains of common carp to infection by Aer.
hydrophila has been documented with crosses derived from Tata and Szarvas 15
parents being most resistant whereas fi sh from the wild strains Duna and Amur were
the most resistant. (Jeney et al. 2011 ).
Vaccine Development
Some attention has been devoted to developing vaccines, with commercial products
becoming available. Simple preparations of inactivated whole cells, ECPs or OMPs,
which may be administered by immersion, injection or via the oral route, work well
Aeromonas hydrophila
of cytosolic calcium homeostasis initiating the activation particularly of calpain-2,
which leads to caspase-3 mediated apoptosis (Banerjee et al. 2012 ).
Clearly, the evidence indicates the involvement of both endo- and exo-toxins in
the pathogenesis of Aer hydrophila infections. It still remains for further work to
elucidate the precise mechanism of action.
Evidence from Molecular Analyses
By comparing a virulent and avirulent culture, suppression subtractive hybridization (SSH) was used to identify genetic differences, with the results highlighting 69
genomic regions absent from the latter (Zhang et al. 2000 ). Genes considered to
represent known virulence attributes included haemolysin, histone-like protein, oligoprotease A, OMP and multi-drug resistance protein. Other genes encoded synthesis of O-antigen (Zhang et al. 2000 ).
Quorum Sensing
Quorum sensing has been linked to virulence of Aer. hydrophila in burbot ( Lota
lota ). Using quorum sensing mutants – involving N-(butyryl)-L-homoserine lactone
production and receptor mutants – less mortalities developed compared to use of the
wild type culture. Moreover, virulence was restored in the mutants by the addition
of N-butyryl-L-homoserine lactone. Conversely, the addition of quorum sensing
inhibitors protected the burbot larvae from the virulent organism (Natrah et al.
2012 ).
Disease Control
Disease Resistant Fish
The differential resistance of four strains of common carp to infection by Aer.
hydrophila has been documented with crosses derived from Tata and Szarvas 15
parents being most resistant whereas fi sh from the wild strains Duna and Amur were
the most resistant. (Jeney et al. 2011 ).
Vaccine Development
Some attention has been devoted to developing vaccines, with commercial products
becoming available. Simple preparations of inactivated whole cells, ECPs or OMPs,
which may be administered by immersion, injection or via the oral route, work well
Aeromonas hydrophila