Table 1 Pathogenicity of wild-type and HN-mutated viruses in SPF embryonated chicken eggs and chickens.
Virus |
|
| IVPI§ |
|---|---|---|---|
rG7- wt | 44 | 1.7 | 2.4 |
rG7- P93A | 56 | 1.56 | 0.76 |
rG7- L94A | 60 | 1.18 | 0.58 |
Mean death time (MDT) pathotype definition: virulent strains, <60 h; moderately virulent strains, 60 to 90 h; avirulent strains, >90 h.
Intracerebral pathogenicity index (ICPI) is the criterion to classify the virulence of NDV isolates as recommended by the OIE. Pathotype definition: virulent strains, 1.5 to 2.0; moderately virulent strains, 0.7 to 1.5; avirulent strains, 0.0 to 0.7.- §Intravenous pathogenicity index (IVPI): velogenic strains yield values greater than 2.0, while avirulent strains approach 0.0.
Mean death time (MDT) pathotype definition: virulent strains, <60 h; moderately virulent strains, 60 to 90 h; avirulent strains, >90 h.
Intracerebral pathogenicity index (ICPI) is the criterion to classify the virulence of NDV isolates as recommended by the OIE. Pathotype definition: virulent strains, 1.5 to 2.0; moderately virulent strains, 0.7 to 1.5; avirulent strains, 0.0 to 0.7.