Human Milk Contains Elements That Block Binding of Noroviruses to Histo-Blood Group Antigens in Saliva

Abstract

Noroviruses (NORs), previously known as Norwalk-like viruses, belong to one of four genera of caliciviruses. NORs mainly cause epidemics of acute gastroenteritis in humans. We found that NORs recognize human histo-blood group antigens as receptors. Recombinant virus-like particles (VLPs) of the prototype Norwalk virus (NV) specifically bind to human intestinal sections and saliva of secretors but not of nonsecretors (Marionneau et al. 2002). Human volunteer studies showed that nonsecretors who do not express the receptor antigens were naturally resistant to NV challenge (Lindesmith et al. 2002). Extended studies with additional NOR strains showed that different NOR strains recognize different receptors defined by the ABO, Lewis, and secretor types (Huang et al. 2003). Four binding patterns of NORs have been described based on studies of saliva samples. Three patterns bind to saliva of secretors with ABO, AO, and AB types, and one pattern binds to saliva containing Lewis epitopes. The sugar moiety of these antigens are believed to be involved in NOR binding.