The first applied use of viral specific DNA technology
in avian disease diagnosis, was marked by the
development of tests for the Psittacine Beak and
Feather Disease (PBFD) and avian polyoma (APV) viruses
(Psittacine Research Group, University of Georgia).
Research Associates Laboratory (RAL) has commercially
offered these tests since 1992 and is both the oldest
and largest molecular biology based laboratory serving
the veterinary community.
RAL's DNA based diagnostics, use viral specific
nucleic acid probes, to identify the unique DNA
sequence making up the desired viral genome. These
sequences are detected in DNA extracts from submitted
blood and tissue swab samples. DNA amplification
techniques coupled with internal sequence probes allow
for diagnostic tests of extreme specificity and
sensitivity.
The performance of RAL's diagnostic tests has been
evaluated both in-house and by an independent
biotechnology laboratory. Test sensitivity, which is
how accurate the test is in reporting a positive
infected bird, as positive, is 99.7% for PBFD and
98.2% for APV.(2) The accuracy of the tests in
reporting a negative infected bird as negative was
100% for both tests.
Aviculturalists and veterinarians should be keenly
aware of the intense capabilities of these diagnostic
methods. The presence of contaminating virus in areas
of high avian traffic (hospitals, stores, aviaries etc
... ) should not be underestimated. Prudent sample
collection and handling is necessary to prevent
environmental contaminants from producing a positive
test result. The levels of test specificity
demonstrated above show that the incidence of
"false-positive" test results is virtually
non-existent in these tests.
PLEASE NOTE
** Aviculturalists should also keep in mind that
infection does not always equal disease.**
The majority of birds exposed to these viruses will
remain clinically normal and mount an effective immune
response which eliminates the virus. These birds are
in essence "naturally vaccinated" and test positive
only throughout the time active virus is present.
Recent advances in RAL test technology allow for a
quantitative (numerical) value to be assigned to the
DNA test results. This valuation of test data helps to
differentiate an active viral infection from
non-progressive viral exposures. Results of this
nature will prove useful in the management of test
positive individuals in the near future.
Who knows perhaps it's all that land clearing up there
that has caused a defiency in the diet?
John A. Gamblin
__________________________________________________
Do You Yahoo!?
Yahoo! Sports - Coverage of the 2002 Olympic Games
http://sports.yahoo.com
Birding-Aus is on the Web at
www.shc.melb.catholic.edu.au/home/birding/index.html
To unsubscribe from this mailing list, send the message
"unsubscribe birding-aus" (no quotes, no Subject line)
to
|
