Hello all --- this is our experience with ELISA for detecting viruses in
Phalaenopsis mother plants used for cloning stock --
1) ELISA is not a very reliable test, giving negative results when the
virus titer is low and below "detection".
2) ORSV and CyMV are very virulent in Phalaenopsis and the slightest
mistake may infect what were once clean mother plants.
ELISA is an antibody reaction, where antibodies that are "color coded"
bind to the virus particles on the sample, thus more intense color means
more virus particles and that is a positive result for that particular
virus. When the virus titer is low, the result may be a color reaction
that is so light that it might be wrongly interpreted as a negative
result.
PCR (Polymerase Chain Reaction) is a DNA test, where the virus RNA is
identified and artificially multiplied thousands of times. The sample
is then run on an electrophoresis gel and we look for the "bands" that
identify that particular RNA. In essence, even if one viral particle is
present we can multiply it thousands of times to make it more detectable
by the test.
PCR is expensive, a lot more expensive than ELISA, therefore the testing
of the stock has to be done gradually. Now, how does that affect the
plants that we currently have in the lab? Initially not by much,
because we have just finished developing the protocols for such PCR
test. But for the future (2-3 years) we will have a lot more security
in saying that the plants will be virtually free of CyMV and ORSV
infections. But the task is a big one, since all of the mother stock
has to be re-tested using PCR and the ultimate goal is to only introduce
stock that has been PCR tested.
The above information came from one of the owners of our primary cloning
lab. The task is very complicated because they had been using the
unreliable ELISA tests and have been cloning and randomly retesting the
clones using ELISA - there are hundreds of different Phalaenopsis mother
plants being cloned at present from several different nurseries, all
having different standards of cleanliness.
Terry A. Glancy
Pine Ridge Orchids, Inc.
21100 SW 300 Street
Homestead, FL 33030-7812
ph (305) 247-4839
(305) 247-3086
fx (305) 247-8853
Website = http://www.PineRidgeOrchids.com
Email = [EMAIL PROTECTED]
Cc Email = [EMAIL PROTECTED]
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