Question
Elusion
Answer
Elution (assuming the intended term, given the context of this Microbiology/Virology paper) refers to the phenomenon by which certain viruses, having first adsorbed onto (agglutinated) red blood cells via a haemagglutinin, subsequently spontaneously detach (elute) from the RBC surface after a period of incubation — most classically described for influenza virus and other orthomyxoviruses/paramyxoviruses.
Mechanism: the viral neuraminidase enzyme, present on the viral envelope alongside haemagglutinin, progressively cleaves the sialic acid receptors on the RBC surface to which the haemagglutinin had bound; once sufficient sialic acid has been removed, the virus can no longer remain attached and is released (eluted) from the cell — the RBCs are then rendered permanently resistant to re-agglutination by the same virus, since their sialic acid receptors have been enzymatically destroyed (though they remain susceptible to a different virus using a different receptor).
Significance: elution demonstrates that viral hemagglutination is a reversible, enzyme-mediated, receptor-destroying process (rather than a fixed, permanent binding), a historically important observation in understanding viral-host cell receptor interactions and receptor-destroying enzyme (RDE) activity; the phenomenon underlies the classical haemagglutination-inhibition (HI) test methodology considerations, and elution kinetics can be used experimentally to help characterize/distinguish different haemagglutinating viruses based on their elution rate and the temperature-dependence of the process.