TABLE 2.

Plaque size on MDBK cells

Virus	Size (mm)a	% Wild type	Pb with respect to:
			PRV Be	PRV 91
PRV Be	1.20 ± 0.11	100	ND	<0.005
PRV 91	0.83 ± 0.06	69	<0.005	ND
PRV 25	0.80 ± 0.07	67	<0.005	0.04
PRV 104	1.11 ± 0.06	93	<0.005	<0.005
PRV 105	1.02 ± 0.08	85	<0.005	<0.005
PRV 106	1.24 ± 0.07	103	0.051	<0.005
PRV 107	0.82 ± 0.05	68	<0.005	0.278
PRV 107R	1.24 ± 0.06	103	0.077	<0.005

^aPlaque size averages were taken from 40 isolated plaques measured from two independent platings of virus. 

^bDetermined by a Student’s t test. Two numbers were considered statistically different if P was <0.005. ND, not determined.