Biotechnologically produced fucosylated oligosaccharides inhibit the binding of human noroviruses to their natural receptors.

Norovirus infections cause severe gastroenteritis in millions of people every year. Infection requires the recognition of histo-blood group antigens (HBGAs), but such interactions can be inhibited by human milk oligosaccharides (HMOs), which act as structurally-similar decoys. HMO supplements could help to prevent norovirus infections, but the industrial production of complex HMOs is challenging. Here we describe a large-scale fermentation process that yields several kilograms of lacto-N-fucopentaose I (LNFP I). The product was synthesized in Escherichia coli BL21(DE3) cells expressing a recombinant N-acetylglucosaminyltransferase, β(1,3)galactosyltransferase and α(1,2)fucosyltransferase. Subsequent in vitro enzymatic conversion produced HBGA types A1 and B1 for norovirus inhibition assays. These carbohydrates inhibited the binding of GII.17 virus-like particles (VLPs) to type A1 and B1 trisaccharides more efficiently than simpler fucosylated HMOs, which were in turn more effective than any non-fucosylated structures. However, we found that the simpler fucosylated HMOs were more effective than complex molecules such as LNFP I when inhibiting the binding of GII.17 and GII.4 VLPs to human gastric mucins and mucins from human amniotic fluid. Our results show that complex fucosylated HMOs can be produced by large-scale fermentation and that a combination of simple and complex fucosylated structures is more likely to prevent norovirus infections.