Method for screening influenza neutralizing antibodies in crude human plasma and its derivatives using SPR

We applied Surface Plasmon Resonance (SPR) technology to develop a method for potency screening and quantification of anti-influenza antibodies in minimally processed human plasma samples and intravenous immunoglobulin (IGIV) products. We found that specific antibodies in human plasma or IGIV capable of inhibiting binding of influenza hemagglutinin to receptor -analogous glycans do so in concentration-dependent manner. We ranked the inhibitory activity of plasma samples from multiple donors and found a good correlation (r = 0.87) of SPR assay measurements and conventional hemagglutination inhibition (HAI) assay results. This method was also applied to screen for specific anti-influenza antibodies in IGIV lots manufactured pre -and post-2009 H1N1 pandemic. The SPR method was also applied to study binding inhibition of the intact A/California/04/2009 H1N1 and B/Victoria/504/2000 influenza viruses to & alpha;2,6 or & alpha;2,3-linked synthetic glycans. In contrast to recombinant H1 hemagglutinin, which was found to interact primarily with & alpha;2,6-linked terminal sialic acids, intact H1N1 or influenza B virus recognized both types of receptor analogs with different observed dissociation rates and the inhibitory activity of plasma antibodies was dependent on the type of sialic acid link. The SPR method can provide a high-throughput, time-saving and semi-automated alternative to conven-tional assays such as HAI or microneutralization in situations where screening of large numbers of plasma donations to identify high titer units is needed to product highly potent immunoglobulins.

Automated summary

We developed a method using Surface Plasmon Resonance (SPR) technology for screening and quantifying anti-influenza antibodies. The method showed a concentration-dependent inhibition of influenza hemagglutinin binding by specific antibodies in human plasma or intravenous immunoglobulin (IGIV) products. The SPR assay results correlated well with the conventional hemagglutination inhibition (HAI) assay results. This method can be used to identify high titer units in a high-throughput and time-saving manner.