- Salmonid alphavirus (SAV; pancreas disease, sleeping disease)
- Reverse transcription polymerase chain reaction (RT-PCR) testing for SAV is available
for:
- Individual serum samples
- Pooled serum samples
- Tissue samples (heart or gill is recommended)
- Broodstock testing
- Ovarian fluids
Test accredited
to UKAS
ISO/IEC 17025:2005
Which
sample
to submit?
- Individual sera. Based on our experience with experimental
and natural infections, SAV may be detected in the serum of individual Atlantic salmon and rainbow trout
for 2-3 weeks following infection. As neutralizing antibodies appear, virus becomes undetectable. Therefore
positive serum results are consistent with active infection in the sampled fish population.
- Pooled sera. We have shown that testing of pooled serum samples can
be used as a cost-effective means of screening populations for evidence of active infection. It is recommended
that no more than 10 sera are pooled and that sera from different groups (e.g. cages, raceways) are
pooled separately to aid interpretation.
- Tissues. We have shown that positive RT-PCR signals can persist in
tissues for many months. In a study of gill, heart, kidney, brain and pancreas, the signal from heart
and gill were most persistent. Therefore heart or gill are the tissues of choice. Given the persistence
of signal following infection, testing of tissues gives an indication of the historical status of the
population under test i.e. exposed or not exposed (similar to the use of serology) but does not necessarily
indicate active infection at the time of sampling (parallel testing of serum by RT-PCR, serology or
histopathological examination of tissues can be of assistance).
SAV
subtype determination by sequence analysis
- This service analyses part of the viral genetic material to determine the
subtype of the virus and its potential relationship to previously examined strains.
- Other assays are also available- please contact us with individual requests:
info@afbini.gov.uk
- RT-PCR
- Serum should be separated and sent on ice. Avoid freezing if possible.
- Tissues should be sent in RNAlater (see below) or a similar preservative which helps preserve
ribonucleic acid (RNA) in tissue samples, preventing false negative results due to RNA degradation during
transport and storage.
- Submission of tissues in RNAlater or similar RNA stabiliser.
- Tissue should be immediately placed in at least 10 volumes of the reagent (or approximately
10μl reagent/mg tissue). To ensure rapid and reliable stabilization of RNA even in the inner parts of
solid tissues, the sample must be cut into slices less than 0.5 cm thick. The slices can be any convenient
size, provided one dimension of the sample is <0.5 cm. Organs smaller than this do not require slicing:
the entire organ can be placed in RNAlater. If possible submit duplicate cubes of tissue, 2.5-3mm3
- RNAlater is available on request from the fish disease unit.
- Note, great care should be taken when sampling to avoid cross contamination of samples
that would result in false positive results. The use of disposable instruments is one approach to this
problem.
Additional RT-PCR tests available
- ISAV
- IPNV
(we have two assays available- one is specific for serotypes Sp and Ab (A2 and A3) while the other is
designed to detect all nine serotype A strains, although with slightly reduced sensitivity.
- Atlantic
salmon paramyxovirus (ASPV)
- Piscichlamydia salmonis
- Neoparamoeba
spp (a generic assay which will detect a range of species)
- Neoparamoeba
perurans (a specific assay to test for this presence of this species which is considered pathogenic
in relation to gill disease)
- Koi herpes virus
- Ostreid herpes virus
1 (screening and confirmation of μ variant)
For more information contact:
Fish Diseases Unit
Veterinary Sciences Division
Stoney
Road
Stormont
Belfast
Download sample submission form
