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F.A.Q.

TESTING AND RESULTS

What do my test results mean?
The reference control is out of range, what does this mean?
What should I do when a low number of samples test positive when expecting 100% negative results?
Is there a difference between serum and plasma in ELISA testing?
Why should I run a reference control? The kit already has 2 controls

SAMPLING

What is the number of samples I should take of a flock or herd?
How long can I store serum samples?
What quantity of blood should I take?
Sample looks different, what should I do?
Can I pool samples?
How can I collect serum from blood samples?
What effect do poor quality samples have on results? Or why can't we use poor quality samples?

REAGENTS

What’s the difference between the green & yellow sample diluent? Can they be shared?
Can I use poultry kit sample diluent for a swine test?
What reagents of poultry & swine kits can be shared?
If I dilute samples using Idexx diluent, can I run them on the BioChek ELISA and vice versa?
What happens if I use the wrong BioChek diluent?
How long does the wash buffer last after mixing?
What will happen if I use another wash reagent or just DI water?
Will the BioChek wash in my system mess up results from Idexx or Synbiotics assays?
If so, what is recommended regarding cleaning procedure to clear out the wash when changing systems?

GENERAL

Can I send samples to BioChek for routine testing?
What kind of information is available with the BioChek ELISA kits?
Can I use the BioChek reference control for an Idexx kit?
I have my own internal reference controls, can I use those? If so, why do I need to use the BioChek reference controls?




TESTING AND RESULTS

Q: What do my test results mean?
A: There are 3 conditions for interpretation of test results:
1. The test results must be valid and accurate. This can be done by running a sample with a known value together with the new (your) samples. BioChek laboratories usually do so. The name of the known sample has the prefix RF or RS. Please check with the laboratory

2. A statistically valid number of samples should be tested ( interpretation manual 2012 vs 3 page 6)

3. One should know what result to expect prior to sending out samples for testing (interpretation manual page 18 and further)


Q: The reference control is out of range, what does this mean?
A: This means something went wrong when running the test. Please make sure you’re using the correct range corresponding to the reference control sample used. Contact BioChek for more help


Q: What should I do when a low number of samples test positive when expecting 100% negative results?
A: Re-run the positive samples. Make a fresh dilution and test again. If still positive, use an alternative test for confirmation. Only run the positive samples!


Q: Is there a difference between serum and plasma in ELISA testing?
A: No, not for ELISA purposes. (The term serum relates to blood plasma without clotting factors like fibrinogen).


Q: Why should I run a reference control? The kit already has 2 controls
A: The kit controls only show the kit differentiates between positive and negative samples. The reference control will confirm quantitative accuracy. Think about it like this: a straight line is defined by two points, however to fix the angle of the line one needs a third point.


SAMPLING

Q: What is the number of samples I should take of a flock or herd?
A: For poultry, common practice is to take 18 to 23 samples per house (airspace). (Interpretation manual 2012 vs 3 page 6)
For swine, common practice is to take about 6 – 8 samples per type


Q: How long can I store serum samples?
A: Frozen in an airtight tube, one can store samples for years. However, at least 40% of the tube should be filled with serum. In a refrigerator, between 3 – 8 days


Q: What quantity of blood should I take?
A: About 1-2 ML will do in general for ELISA. However, if confirmatory testing has to be done then more is recommended


Q: Sample looks different, what should I do?
A: Samples should be clear and should not smell. Differences in colour can be normal. Discard obviously spoiled samples


Q: Can I pool samples?
A: The reason for testing can be to confirm success of a vaccination or to screen flocks for positive samples.
Confirmation of the success of vaccination is determined by the mean titer and the %CV. The %CV is a measure for uniformity. You lose true %CV when pooling samples.

When screening for positive samples, pooling might dilute a weak positive sample in negative samples. The test result of the pooled sampled might be negative while in fact one of the samples is positive.


Q: How can I collect serum from blood samples?
A: Let the sample clot in air. Let the tube with blood stand at an angle allowing for the maximal surface of blood to be in contact with air. Let it stand until enough serum is visible. Certrifugation: spin at 15000 RPM for about 15 minutes


Q: What effect do poor quality samples have on results? Or why can't we use poor quality samples?
A: Difficult to say. However proteins and thus antibodies might get metabolized in poor quality serum samples. Another factor is fat; this might cause false positive reactors


REAGENTS

Q: What’s the difference between the green & yellow sample diluent? Can they be shared?
A: Green diluent is the standard diluent. The yellow diluent of BioChek helps avoiding non specific binding. (For more information, refer to BioChek Plate Dilution Procedure 5ul 2008


Q: Can I use poultry kit sample diluent for a swine test?
A: No you cannot, in principle always use homogenous reagents


Q: What reagents of poultry & swine kits can be shared?
A: All reagents have a product code and a batch number. These may only be interchanged provided the batch numbers are the same.


Q: If I dilute samples using Idexx diluent, can I run them on the BioChek ELISA and vice versa?
A: The chemical composition of the two diluents is different. It is so different that one cannot use one on the other kit.


Q: What happens if I use the wrong BioChek diluent?
A: The green diluent might give slightly higher titers than the yellow diluent


Q: How long does the wash buffer last after mixing?
A: Up to a few weeks or longer. Make sure the container is shaken (not stirred!) prior to use


Q: What will happen if I use another wash reagent or just DI water?
A: These may cause incorrect results. Do not do this. Contact your supplier for spare wash solution


Q: Will the BioChek wash in my system mess up results from Idexx or Synbiotics assays? If so, what is recommended regarding cleaning procedure to clear out the wash when changing systems?
A: After using BioChek wash solution make sure you rinse the system. This must be done in all cases after completing the washing for the day with BioChek or when switching to another wash solution.


GENERAL

Q: Can I send samples to BioChek for routine testing?
A: BioChek doesn’t provide that service. We can recommend laboratories in your region


Q: What kind of information is available with the BioChek ELISA kits?
A: We have information on validation, applications and interpretation of the kit, and we have technical laboratory personnel run our assays.


Q: Can I use the BioChek reference control for an Idexx kit?
A: As the BioChek reference control is diluted in BioChek diluent it cannot be run on any other kit. Only use it on BioChek products.


Q: I have my own internal reference controls, can I use those? If so, why do I need to use the BioChek reference controls?
A: There is no specific need to only use BioChek reference controls. The advantage however of running the BioChek reference control is that we have the same controls in house, so we can compare results.