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Detection of virulent strains of Newcastle disease virus in chickens previously infected with Australian strains of the virus
By H.A.Westbury
Australian Animal Health Laboratory
August 2004
RIRDC Publication No 04/022 RIRDC Project No CSA-1J
The test also detected NDV in the tissues of immune and non-immune chickens that were infected with virulent virus, though certain tissues, bone marrow and spleen, were better targets for testing than others. However, the vELISA was not as sensitive at detecting the virus as VI or PCR. Indeed in terms of sensitivity PCR was better than VI, which was better than vELISA. The vELISA was only about 50% as sensitive as VI, and about 44% as sensitive as PCR. The vELISA, in fact, failed to detect NDV in some infected chickens and therefore was not considered to be suitable as an individual bird test.
Independent assessment of the value of the test as a virulent ND (vND) diagnostic test was undertaken by the Australian Animal Health Laboratory (AAHL) diagnostic team. They took advantage of specimens collected during the outbreaks of vND in NSW from 1998-2000 and their experience during that outbreak. Their assessment was that the test worked, albeit less sensitively than alternatives, but that it failed to provide critical information about the pathogenicity of the virus detected. Such information was considered to be vital given the very complex situation that existed with NDV in Australia. They therefore felt that the vELISA provided only marginal benefits, at best, and that their efforts were better directed at developing rapid tests based on the real-time PCR platform as this would provide information concerning both the detection of NDV plus vital data on it’s virulence, in a shorter timeframe than the vELISA could be performed.
 
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