Simultaneous alteration of residues 279 and 284 of the VP2 major capsid protein of a very virulent Infectious Bursal Disease Virus (vvIBDV) strain did not lead to attenuation in chickens

Table 2 Pathogenicity of the rescued P2 and P2/PO7 molecularly engineered IBDV viruses in SPF chicken

Virus	Group^a	Score^b	B/BW ratio^c	S/BW ratio^d	Dead^e
P2/PO7	1	3	2.936	1.834	9/10
P2	2	0	4.788	1.959	0/10
-	Control	0	7.024	2.041	0/10

^aGroups of 10 SPF chickens each were inoculated at the age of 3 weeks with either P2 virus or P2/PO7 mutant virus collected from the supernatant of transfected CEF cells. Chickens in the control group were inoculated with PBS.
^bScore 0: no damage; score 1: mild damage; score 2: moderate damage; score 3: severe damage.
^cB/BW: (average bursa in grams·1000)/total body weight in grams. Values show the averages for 10 chickens.
^dS/BW, (average spleen in grams·1000)/total body weight in grams. Values show the averages for 10 chickens.
^eNumber of dead chickens at 3 days post-inoculation.

ISSN: 1743-422X