Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 2/8/2005
Publication Date: 7/17/2005
Citation: King, D.J., Kapczynski, D.R., Afonso, C.L., Piacenti, A. 2005. Contrasting results from molecular and biological pathogenicity assays of newcastle disease virus isolate Iowa 1519 [abstract]. American Association of Avian Pathologists, p.33. Interpretive Summary:
Technical Abstract: A Newcastle disease outbreak in turkeys in Iowa during the early 1970s was the source of an isolate identified as Iowa 1519. The isolate was classified as a neurotropic velogen based on an intracerebral pathogenicity index of 1.93, an intravenous pathogenicity index of 2.64, and neurotropic clinical disease and mortality following intracloacal inoculation of SPF chickens. However, nucleotide sequence analysis of the RT-PCR amplified product from the tested isolate stock revealed the fusion protein cleavage site amino acid sequence was typical of a low virulence Newcastle disease virus, the first isolate yielding contrasting results with different pathogenicity assays. Additional testing has revealed that the virus stock is a mixed population of low and high virulence components and demonstrates the potential risk of virus classification based on a single test. Testing of virus isolates from turkeys infected with the mixed population virus stock is being completed.