| Method |
Eighty 11-day embryos were inoculated allantoically with about one
ID50 of BEL. Every third hour from the ninth hour, 0.05 ml of allantoic
fluid was removed from each embryo and stored at -70°. From the
eighteenth hour, a second sample was also taken and tested for the
presence of hemagglutinin. The experiment was arbitrarily terminated
at 48 hours. With the embryos thus classified according to the time of appearance of hemagglutinin, it was possible to go back to the earlier
samples and determine growth curves for different times of appearance
of hemagglutinin. |