Table 1.

Mean viral gene copies detected in allantoic fluid and mean days of embryonic death by infection with a low concentration (1 EID₅₀) of wild and vaccine strains of TW2575/98

Viruses	Viral gene-detected chicken embryos (n/26)a	Mean of the viral gene copy number (n × 109/µl)	Mean days of embryonic death after DPI
TW2575/98w	13	15.90 ± 16.67b*	6.62 ± 1.39*
TW2575/98vac	13	57.99 ± 53.64*	4.54 ± 2.11*

DPI means day post-inoculation

^*Significant difference between wild and vaccine strains (p < 0.05)

^a26 chicken embryos were inoculated with each virus (TW2575/98w and TW2575/98vac) and incubated for 7 days

^bMean ± SD