Protection against Multiple Subtypes of Influenza Viruses by Virus-Like Particle Vaccines Based on a Hemagglutinin Conserved Epitope

Table 1

Protection against a lethal PR8 virus challenge in mice by intranasal (i.n.) administration of various doses of LAH-HBc with or without .

Group	Immunogen	Immunization route	Dosage (μg)	Protection against PR8 virus challenge
				Lung virus titers (log10TCID50/mL)	Survival mice/tested mice
A	LAH-HBc + CTB^*	i.n.	25	5.92 ± 0.52^b	10/10
B	LAH-HBc	i.n.	25	6.03 ± 0.38^b	10/10
C	LAH-HBc + CTB^*	i.n.	5	6.33 ± 0.35	8/10
D	LAH-HBc	i.n.	5	6.47 ± 0.79	5/10
E	LAH-HBc + CTB^*	i.n.	1	6.88 ± 1.45	5/10
F	LAH-HBc	i.n.	1	7.35 ± 1.22	0/10
G	CTB^*	i.n.	—	7.87 ± 0.79	0/10
H	Control	i.n.	—	7.60 ± 0.52	0/10

BALB/c mice were randomly divided into eight groups. Six groups of mice were immunized intranasally with various doses of LAH-HBc vaccine alone or in combination with CTB^*. The CTB^* alone group was used as an adjuvant control, and the unimmunized group served as a negative control. Three weeks after the last immunization, mice were challenged with a lethal dose (5 × LD₅₀) of influenza virus (A/PR/8/34 (H1N1)). Bronchoalveolar washes were collected 3 days after infection for titration of lung virus. The survival rate of mice 21 days after infection was determined.
^bSignificant difference compared to the mice in the control group ().