Table 1. Cleavage site sequence of parental and recombinant APMV-4 viruses and pathogenicity in MDT and ICPI assays.
| Virus | Cleavage site | MDTa | ICPIb | |
| Sequence | Furin motif | |||
| wtAPMV-4 | DIQPR ↓F | - | >168 | 0.00 |
| rAPMV-4 | DIQPR ↓F | - | >168 | 0.00 |
| rAPMV-4/Fc type 3-Q | RPQGR↓F | - | >168 | 0.00 |
| rAPMV-4/Fc type 5-Q | KRQKR↓F | + | >168 | 0.00 |
| rAMPV-4/Fc BC | RRQKR↓F | + | >168 | 0.00 |
| rAMPV-4/Fc LaSota | GRQGR ↓L | - | >168 | 0.00 |
| rAMPV-4/Fc SV | VPQSR↓F | - | >168 | 0.00 |
| rAMPV-4/Fc PIV 1 | NPQTR↓F | - | >168 | 0.00 |
a
Mean embryo death time (MDT): the mean time (h) for the minimum lethal dose of virus to kill all of the inoculated embryos. Pathotype definition: virulent strains, <60 h; intermediate virulent strains, 60 to 90 h; avirulent strains, >90 h.
b
Intracerebral pathogenicity index (ICPI): pathogenicity of NDV in 1-day-old SPF chicks following intracerebral inoculation. Pathotype definition: virulent strains, 1.5–2.0; intermediate virulent strains, 0.7–1.5; and avirulent strains, 0.0–0.7.