Induction of cross-protection against influenza A virus by DNA prime-intranasal protein boost strategy based on nucleoprotein

Table 1 Protection against lethal PR8 virus challenge in mice by DNA prime intranasal protein boost strategy based on NP

Group	Immunization		Lung virus titer (log₁₀TCID₅₀/ml)^a			Survival rate (No. of survivors/no. tested)
Group	DNA prime	rNP boost	3 days	5 days	7 days	Survival rate (No. of survivors/no. tested)
D1	once	-	7.24±0.25	6.39±0.08	5.02±0.45	0/10
D2	twice	-	7.14±0.43	5.63±0.32	4.35±0.14 ^b	1/10
P1	-	once	6.94±0.42	5.78±0.42	5.24±0.25	1/10
D1P1	once	once	6.41±0.16^b	4.68±0.39^b	1.16±0.29^b	8/10^b
D2P1	twice	once	6.13±0.43^b	4.89±0.44^b	0.33±0.58^b	10/10^b
Control	-	-	7.19±0.17	5.89±0.16	5.28±0.25	0/10

Mice were immunized as described in section of methods. 3 weeks after the last immunization, mice were challenged with a lethal dose (5×LD₅₀) of influenza PR8 virus. Bronchoalveolar washes from three mice in each group were collected 3 days, 5 days and 7 days post-infection for titration of lung virus respectively. The survival rate of mice 21 days post-infection was determined.
^a Results are expressed as mean ± SD of tested mice in each group.
^b Displays significant difference compared with mouse in control groups (P<0.05).

ISSN: 1743-422X