Biolayer interferometry is insufficiently sensitive for direct measurement of IgM quantity and avidity in Atlantic salmon (Salmo salar) serum.

Quantification of specific antibodies underpins the assessment of adaptive immunity in response to vaccination or infection and is performed by enzyme-linked immunosorbent assay (ELISA). A biolayer interferometry (BLI) assay was recently developed that simultaneously quantifies IgM antibodies and their avidity in giant grouper (Epinephelus lanceolatus) sera and proved to be a robust, repeatable and more high-throughput alternative to ELISA [1]. Here we attempted to optimise a similar single-step BLI assay using an Octet HTX instrument to quantify IgM specific to the hapten 2,4-dinitrophenol (DNP) in serum from Atlantic salmon (Salmo salar) primed and boosted with DNP conjugated to keyhole limpet hemocyanin.