TABLE 2.

Genotype and phenotype of the mutant viruses and complementing cell lines as determined by the plating efficiency assay

Virus	Plating efficiency (PFU/ml) of wild-type (KOS) and mutant viruses on:
	Vero cells	C32 cells	31 cells
KOS	8.8 × 109	9.3 × 109	6.8 × 109
K5ΔZ	3 × 105	2.10 × 109	2.29 × 109
K23Z	1 × 105	2.63 × 109	4 × 105
KΔ18-19G	<104	3.8 × 108	<104