. 2013 Aug 2;4(6):489–493. doi: 10.4161/viru.25952

Table 2. Characteristics of growth efficiency and virulence, and neuraminidase-inhibitor susceptibility of wild-type and mouse-adapted pandemic H1N1 influenza viruses and their oseltamivir-resistant counterpart.

Virus strain	Virus yield		MLD₅₀	MST	Neuraminidase inhibitors IC₅₀ ± SD, nM (Ratio)^a
	MDCK cells	Eggs	MLD₅₀	MST	Neuraminidase inhibitors IC₅₀ ± SD, nM (Ratio)^a
	(Log₁₀TCID₅₀/ml ± SD)	(Log₁₀EID₅₀/ml ± SD)	(Log₁₀TCID₅₀)	(dpi)	Oseltamivir	Zanamivir	Peramivir
CA/04/09	6.1 ± 0.3	6.7 ± 0.5	>5.5	>12	0.86 ± 0.03 (1)	0.6 ± 0.04 (1)	0.16 ± 0.07 (1)
maCA04	7.8 ± 0.2*	8.9 ± 0.4*	2	8	2.53 ± 0.04 (2.9)	1.99 ± 0.05 (3.3)	0.52 ± 0.04 (3.3)
CA04 _H274Y	6.1 ± 0.3	7.1 ± 0.1	>5.5	>12	107.1 ± 0.07 (124.5)	0.33 ± 0.02 (0.55)	13.56 ± 0.03 (84.8)
maCA04 _H274Y	7.7 ± 0.1*	8.4 ± 0.3*	1.5	6	128.1 ± 0.04 (149)	0.48 ± 0.05 (0.8)	27.11 ± 0.05 (169.4)

^a Compared with that of the wt CA/04/09 virus. *P< 0.05 compared with the value for the respective parental viruses (unpaired t test, two-tailed). SD, standard deviation; MLD, mouse lethal dose; MST, median survival time; wt, wild type; ma, mouse adapted.