Table 1. Antiviral activity of Spirulina extract against influenza virus strains in vitro.

	EC50 (mg/mL)	CC50 (mg/mL)	SI
A/WSN/33(H1N1)	1.17 ± 0.09	23.80	20.34
A/TW/3446/2002(H3N2)	0.98 ± 0.24	23.80	24.28
B/TW/70555/2005	1.33 ± 0.15	23.80	17.89
A/TW/70058/2009(H1N1)*	1.17 ± 0.08	23.80	20.34
A/TW/147/2009(H1N1)*	0.98 ± 0.10	23.80	24.28
A/TW/126/2009(H1N1)	0.58 ± 0.02	23.80	41.03

EC₅₀: 50% effective concentration, based on the inhibition of viral plaque formation.

CC₅₀: 50% cytotoxic concentration, based on the MTT assay.

SI: selectivity index, a ratio of CC₅₀ to EC₅₀.

^*Oseltamivir-resistant influenza strains.

All data represent mean ± SD for three independent experiments.