GI.1 Norovirus Neutralizing Antibody Levels Are Correlated with GI.1 Histo-blood Group Antigen-Blocking Antibody Levels.

BACKGROUND:The in vitro cultivation of human noroviruses allows a comparison of antibody levels measured in neutralization and histoblood group antigen (HBGA)-blocking assays. METHODS:Serum samples collected during the evaluation of an investigational norovirus vaccine (HIL-214 [formerly TAK-214]) were assayed for neutralizing antibody levels against the vaccine's prototype Norwalk virus/GI.1 (P1) virus strain. Results were compared to those previously determined using HBGA-blocking assays. RESULTS:Neutralizing antibody seroresponses were observed in 83% of 24 vaccinated adults, and antibody levels were highly correlated (r=0.81, P<0.001) with those measured by HBGA-blocking. CONCLUSIONS:GI.1-specific HBGA-blocking antibodies are a surrogate for neutralization of GI.1 norovirus.