Mechanisms of the action of povidone-iodine against human and avian influenza A viruses: its effects on hemagglutination and sialidase activities

Table 1 Inhibition by PVP-I of sialidase activity, hemagglutination and infectivity activity of influenza A viruses

Virus subtype	Virus strain	Sialidase inhibition activity IC₅₀^a (μg/ml)	Hemagglutination inhibition activity^b (mg/ml)	Infection inhibitory activity (%)^c
H1N1	A/Bel/42	11 ± 2	1.56	84 ± 1
	A/Texas/36/91	72 ± 4	0.78	68 ± 3
	A/USSR/92/77	47 ± 3	0.78	68 ± 2
	A/PR/8/34	9.5 ± 0.5	0.20	62 ± 2
	A/WS/33	12.5 ± 0.5	0.78	60 ± 4
	A/WSN/33	45 ± 1	0.39	97 ± 1
	A/DK/HK/36/4	21 ± 5	12.50	40 ± 4
H3N2	A/Aichi/2/68	96 ± 2	3.13	82 ± 5
	A/Memphis/1/71	61 ± 4	1.56	66 ± 3
H9N2	A/DK/HK/92/76	212 ± 9	12.50	34 ± 8
H5N3	A/DK/HK/313/78	78 ± 4	12.50	23 ± 1
	A/DK/HK/23/76	124 ± 7	3.13	57 ± 4
	A/DK/HK/677/1	55 ± 1	3.13	50 ± 3

^aIC₅₀values are concentrations inhibiting viral sialidase activity by 50%. Standard error means were calculated from means of two independent experiments, each conducted in duplicate.
^bMinimum concentration that inhibits hemagglutination.
^cPercent viral inhibition (with 1.56 mg/ml of PVP-I) was calculated by comparison with the control without an inhibitor. Each experiment was performed in triplicate.

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