SAGB RESEARCH PRIORITIES 2004

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SAGB RESEARCH PRIORITIES 2004

• NOSAP- HERITABILITY OF DISEASE RESISTANCE
  FACTORS
• Discussion during the current NOSAP project has
  centred on the practicalities of breeding oysters
  which have a broad range of resistance to
  diseases. The approaches to this will be
  different within and outside of the Approved
  Zones for Bonamia. In the Approved Zones, an
  indirect approach to resistance will need to be
  taken i.e. one which does not involve a Bonamia
  challenge.

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• SILTATION OF SOLENT SEVERAL ORDER GROUNDS
• Commercially farmed grounds in the Solent have
  become subject to siltation from an orange
  coloured sediment. This requires urgent
  investigation to ascertain its nature and source.

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SUMMER MORTALITY OF C.GIGAS/VIRUSES OF COMMERCIAL
BIVALVESSAGB has maintained a careful watch on
the spread of Summer Mortality in Europe. On the
basis of the pattern of spread the distribution
appears to be associated with the relaying of
oysters directly or indirectly linked to France.
This has been compatible with a disease agent,
even though French and UK authorities have been
unable to classify it as a disease because of the
lack of a causative organism associated with most
mortalities. A herpes virus has been suspected
and there are good reasons to account for them
not being routinely isolated. Even though it may
only manifest itself in association with
environmental or handling stress, it does now
appear to be a disease.
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• Studies in France have indicated a genetic
  component to susceptibility and the experience of
  one mortality event in Jersey has suggested that
  UK hatchery stocks are more susceptible than some
  French stocks. Although there has only been one
  mortality in mainland UK with the appearance of
  Summer Mortality, the industry is very exposed to
  risk if there were an outbreak which spread.
• In these circumstances the industry regards more
  detailed work on the disease as a priority. CEFAS
  Weymouth have the expertise to study viruses in
  UK stocks of commercial bivalves. SAGB believes
  this should be utilised to ascertain the
  significance of viruses in a range of
  commercially valuable species.

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• HUMAN-TYPE FRNA BACTERIOPHAGES AS INDICATORS OF
  SOURCES OF SEWAGE POLLUTION
• SAGB has long supported work on Fphages, but now
  believes a clear distinction needs to be made
  between those of animal and human origin if they
  are to have real application to public health
  issues. This has been achieved by CEFAS Weymouth,
  but more needs to be done to enable it to be used
  more routinely in pin-pointing sources of human
  pollution.
• Phages from animal pollution are not
  representative of human health risk provided
  bivalves are purified to remove bacteria
  associated with those sources.

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• SAGB has recently been in discussion with the
  Environment Agency and UKWIR, pointing out that
  this technique has the potential to give a more
  accurate view of sources of pollution and their
  significant for water classification and public
  health risks. The two issues are distinct, as
  water classification can be heavily influenced by
  animal sources, whilst public health is
  predominantly linked to human sources.

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• SAGB is already involved in the REDRISK Pillar of
  SEAFOODplus, a major FP6 study, aimed at risk
  management of human viruses. SAGB believes it
  would greatly add to the value of this work if
  human-type bacteriophage was run in parallel at
  the two selected sites. This cannot be funded
  directly from SEAFOODplus, as it is outside of
  the remit, but SAGB believes funding should be
  provided to continue this work at CEFAS Weymouth.
  In addition a site which is reliant on tertiary
  sewage treatment (UV or micro-filtration) needs
  to be studied.

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• EFFECTIVENESS OF UV TERTIARY TREATMENT IN SEWAGE
  TREATMENT WORKS IN INACTIVATING CULTURABLE
  VIRUSES/PHAGES
• Although much work has been done on PCR and
  real-time PCR, these have an inherent shortcoming
  in being unable to distinguish viable particles
  from fragments post UV treatment.

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• In view of the high reliance now placed on UV
  tertiary treatment in an increasing number of
  estuaries, SAGB believes more work needs to be
  done using culturable species, either Fphage or
  human enteroviruses.
• The Environment Agency uses the latter as the
  most routine of viral measurements and so there
  is already a good case for using these.

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• FOLLOW-UP OF REPORTS OF SHELLFISH-RELATED ILLNESS
• These have been at very low levels in recent
  years, but CDSC appear to have no responsibility
  to track sources. The results are reported as
  being of UK origin, without any proof of this
  being so. The industry is being required to work
  to ever higher standards, even though the
  depuration requirement is much more stringent
  than in the rest of Europe.
• The industry urgently needs to know whether any
  outbreaks in recent years have been of UK origin.