Further Observations on the Cultivation of Strains of Poliomyelitis Virus in Developing Eggs. ∗

Summary

Further observations on the cultivation of the murine SK strain of poliomyelitis virus in fertile eggs are reported. This strain has now been carried through 30 passages in eggs. The virus has been found to be widely distributed in the infected embryo. It is easily transmitted from egg to egg by different routes. Embryos from 5 to about 14 days of age seem to serve equally well for the propagation of the virus, but those above 16 days of age fail to support its growth.

The murine MM strain was carried through 10 egg passages; a Stanford mouse passage strain, believed to be a high titer variant of the Lansing strain, tentatively labeled C(M) virus, was carried through 15 egg passages. The GD VII strain of Theilers mouse encephalomyelitis virus was carried through 10 passages. It caused the lowest incidence of embryo deaths of the three viruses cultivated. Five strains of poliomyelitis virus failed to show growth in eggs.