Table 3.

 Comparison of antibody serum neutralization titers against influenza A virus (A) and influenza B virus (B) obtained using ELVIRA^® Flu A‐luc and Flu B‐Rluc cells and Hemagglutination inhibition

A.
Serum	Neg	1	2	3	4	5	6	7	8
ELVIRA Flu A*	<10	1280	160	1280	80	640	1280	1280	1280
HI**	<10	1280	40	1280	20	320	320	320	1280

B.
Serum	1	5	8	9	10
ELVIRA Flu B***	<10	40	80	80	40
HI†	<10	80	160	80	80

*ELVIRA Flu A‐luc cells were infected with A/Wisconsin/56/2005 (500 infectious units/well) that had been incubated for 2 hours with dilutions (1:10 followed by twofold serial dilutions) of human serum samples from eight individuals with an unknown vaccination history and one sample that was negative (Neg). Twenty‐four hours after incubation, the ELVIRA cells were lysed and the luciferase assay was performed. Dilutions with greater than 99% inhibition of luciferase activity relative to virus‐only wells were considered neutralized.

**For the HI assay 1 15 000 infectious units/well were incubated with the same dilutions of the serum samples and 1% guinea pig RBCs was added to the serum/virus mixture. The results were evaluated after 30 minutes of incubation at room temperature by comparing the formation of hemagglutination in serum + virus samples with that in control wells that contained RBCs only.

***ELVIRA Flu B Rluc cells were infected with B/Malaysia2506/04 (500 infectious units/well) that had been incubated for 2 hours with dilutions (1:10 followed by twofold serial dilutions) of five human serum samples from individuals with an unknown vaccination history.

^†For the HI assay 60 300 infectious units/well were incubated were incubated with the same dilutions of the serum samples and 1% guinea pig RBCs added to the serum/virus mixture. The results were evaluated after 30 minutes of incubation at room temperature by comparing the formation of hemagglutination in serum + virus samples with that in control wells that contained RBCs only.