Potency of a vaccine prepared from A/swine/Hokkaido/2/1981 (H1N1) against A/Narita/1/2009 (H1N1) pandemic influenza virus strain

Table 2 Neutralizing antibody titers of mice injected once with the vaccine and virus titers in the lungs after challenge

Vaccine			NT titer to		Virus titer in lungs, mean log PFU/g ±Se^a
Strain	Protein, μg	Formulation	Narita/09	Sw/Hok/81
PBS	-	-	<10, <10, <10, <10, <10	<10, <10, <10, <10, <10	5.0±0.17
Narita/09	4	ES	<10, <10, <10, <10, <10	ND	4.6±0.10
	20	ES	<10, 20, 20, 20, 40	ND	4.6±0.12
	100	ES	20, 40, 80, 160, 160	ND	4.1±0.35
Narita/09	4	WV	40, 40, 40, 80, 160	ND	4.2±0.17
	20	WV	40, 80, 160, 160, 320	ND	3.9±0.25*
	100	WV	320, 320, 640, 1280, 1280	ND	2.4±0.50**
Sw/Hok/81	4	ES	<10, <10, <10, <10, <10	<10, <10, <10, 10, 10	4.6±0.04
	20	ES	<10, <10, <10, <10, <10	<10, 10, 10, 20, 80	4.4±0.02
	100	ES	<10, <10, <10, <10, <10	10, 20, 20, 40, 40	4.7±0.02
Sw/Hok/81	4	WV	<10, <10, <10, <10, <10	20, 40, 40, 40, 80	4.5±0.06
	20	WV	<10, <10, <10, <10, <10	20, 40, 80, 80, 80	4.4±0.04
	100	WV	<10, <10, <10, <10, <10	160, 160, 160, 160, 320	4.3±0.09

Mice were injected with each vaccine subcutaneously. Serum samples were collected 3 weeks after injection.
The animals were challenged by intranasal administration of 106.0 PFU of A/Narita/09.
At 3 days after challenge, lungs samples were collected and virus titers were measured. ES: ether split vaccine, WV: whole inactivated vaccine
a: Data are for 5 mice.
*: P<0.05, vs. virus titers in PBS group.
**: P<0.01, vs. virus titers in PBS group.

ISSN: 1743-422X