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Quality Assurance Unit - Scheme Details

Antibody Detection
PT Number
PT0138
Scheme title
Bluetongue Virus (BTV)
Suitable testing methods
ELISA
Reporting format
cELISA - Test value (% inhibition, S/N% or other) and Interpretation (+ve / -ve / inconclusive). ELISA - Test value (% inhibition, S/N% or other) and Interpretation (+ve / -ve / inconclusive). Authorised report will be published electronically. These will show intended result, origin of sample and results from all participants.
Results to be returned within
21 days
Number of samples in each distribution
5
Sample Type
0.25ml liquid serum (heat treated and PCR not detected)
Samples are bovine or ovine serum taken from animals either vaccinated or naturally or experimentally infected with different BTV serotypes
Packaging and transport details
Non-infectious substance. Normal post or courier. Courier delivery will incur additional costs. Please contact the QA unit for details.
Number of distributions per year
2
Accreditation status
ISO/IEC 17043: 2010 Conformity assessment General requirements for proficiency testing.
Date scheme started
2009
Additional information

Vetqas use samples from a range of sources for PT schemes. Some samples are from experimentally infected animals, some from confirmed field infections and some from vaccinated animals.

We try to use samples that are negative, strongly positive, mid-range and low positive, without going too close to the cut-off point for routinely used tests.  This is to replicate the situation with real samples submitted to diagnostic laboratories. For real samples infection or vaccination may have been recent resulting in a rising antibody (or antigen) concentration, or late where they are high or falling. The samples used help our customers assure the quality of their testing over the full range of clinical samples. 

It is recognised that in some testing situations (e.g. monitoring of poultry flocks post vaccination) low antibody concentrations are very rarely seen and here the sensitivity of the test methodology is not of primary importance. It is also recognised that some testing methodologies are inherently less sensitive than others. Where tests of lower sensitivity are used there are occasions when customers report a negative result for samples with an intended low positive result. When this happens customers are advised to evaluate if this result has significance for the test method they are using and the reason for testing.  In some cases the false negative finding will have no impact on the quality of the routine results issued by the laboratory and at other times the customer should undertake a full investigation as to why a low positive sample was categorised as negative.

The samples provided in the PT schemes should not be considered as reference samples.  The analytical performance of a serological test will, in some cases, depend upon the individual serum tested.  Therefore it is not possible to evaluate the diagnostic sensitivity or specificity of a method or kit based on the limited range of samples in proficiency testing panels.

For any particular analysis Vetqas customers use test kits from a wide range of sources. These may be in-house developed methods or commercial kits. Also customers use a range of methodologies for testing (e.g. ELISA, CFT, AGIDT etc). It is not possible for Vetqas to check all samples using all kits and methodologies available.  Vetqas reports inform customers of the kits used to confirm the status and conformity of the samples. This should be taken into account when customers are investigating a non-intended result.

Notes
For price and detail of distribution months please see price list or contact: vetqas@apha.gsi.gov.uk
Back to PT Schemes Prices & Timetable | Print scheme details | Version 5. February 2018