NEWCASTLE-DISEASE VIRUS - DETECTION AND CHARACTERIZATION BY PCR OF RECENT GERMAN ISOLATES DIFFERING IN PATHOGENICITY

The fusion (F) protein plays an important role in determining the viru lence of Newcastle disease virus (NDV) strains. A reverse transcriptas e-polymerase chain reaction (RT-PCR) is described which amplifies a 36 2 bp fragment encompassing the region of the F protein most important for pathogenicity. A specific PCR product was obtained independent of strain, pathogenicity and host of origin. Sequencing of the region spe cifying the F protein cleavage site confirmed the correlation between deduced amino acid sequence and pathogenicity. Oligonucleotides corres ponding to the sequence of the pathospecific region were designed for recent German NDV isolates and labelled with digoxigenin. Hybridizatio n of PCR fragments of different isolates with pathotype-specific oligo nucleotides allowed an estimation of the pathogenicity of most isolate s. Results were in good agreement with experimentally determined ICPI values.