Table 2. DAS181 inhibits pandemic IFV A(H1N1): Viral Yield in MDCK culture (log10 infectious particles per 100 µl).

Virus	PBS	DAS181 0.04 µM	DAS181 0.16 µM	DAS181 0.63 µM	DAS181 2.5 µM	DAS181 10 µM
A/Mexico/4604/2009	5.4±0.4	4.4±0.4	<1	<1	<1	<1
A/California/04/2009	3.5±02	3.1±0.3	2.8±0.7	2.0±0.7	<1	<1
A/Hawaii/31/2007	5.4±0.4	3.2±1.1	2.5±1.2	<1	<1	<1
A/Hawaii/21/2007 (H274Y)	5.3±0.3	<1	2.3±2.4	<1	<1	<1

MDCK cells were pretreated with DAS181 for 2 hours (at indicated concentrations) before infection with A/Mexico/4604/2009, A/California/04/2009, or seasonal influenzas A/Hawaii/31/2007 or A/Hawaii/21/2007 (oseltamivir-resistant H274Y mutant) at M.O.I. ranging from 0.001 to 0.005 MOI. At 24 hrs p.i. the cells were immunostained to detect NP viral antigen (Table 1). Simultaneously the viral yield in the culture supernatants (media above the cell monolayers) collected from individual well was determined and expressed as log10 infectious particles per well (“Viral Yield”), a measure of released infectious viral progeny. Limit of detection in viral yield assay is 10 infectious particles per 100 µl and all values below this are marked as <1. Values represent mean±SD of quadruplicate experiments.