Much attention has been given to the factors that influence detection of neutralising titre, such as viral quantification and the use of receptor destroying enzyme (RDE) for serum treatment. Foci counting enabled precise virus quantification and the development of a highly sensitive assay. Pre-treatment of the human sera with RDE significantly reduced the neutralising titres against all strains, with the exception of the seasonal H1N1 (2009/2010) strain. An HI titre of 1:40, which is associated with a 50 % clinical protection against influenza, was equivalent to an AFRNT titre of 1:100-1:200.
In conclusion, the AFRNT is rapid, highly sensitive, and fully automatable; therefore, this test is perfectly suitable for the high-throughput detection of influenza-neutralising antibodies.