Characterization of a porcine enterocyte receptor for group A rotavirus.

We have identified, purified to apparent homogeneity and chemically characterized a biologically-relevant porcine enterocyte receptor for group A porcine rotavirus. Ceramide glycanase digestion followed by acid hydrolysis and monosaccharide compositional analyses indicated the receptor is a family of two GM, gangliosides, one containing N-glycolyl-neuraminic acid and the other N-acetylneuraminic acid. Both gangliosides displayed dose-dependent inhibition of rotavirus binding to, and infectivity of, host cells. Inhibition of infectivity in a focus-forming-unit-reduction assay was achieved with as little as 2 nmols of NeuGcGM3 (50% inhibition with 3.97 nmol) or NeuAcGM3 (50% inhibition with 9.84 nmol) per 10(4) FFU of virus. Preliminary data suggest specific porcine GM3 carbohydrate fine structure or spatial orientation of the sialyloligosaccharide epitopes of the holoGM3 gangliosides may be crucial to enterocyte receptor recognition by rotavirus. We have quantified both NeuGcGM3 and NeuAcGM3 in enterocytes of various-aged pigs from newborn through 16 weeks and have found with increasing age the amount of both GM3 derivatives, especially NeuGcGM3 per gram (dry weight) intestinal brush border decreases rapidly from newborn through 4 weeks of age. These results may help explain the age-sensitivity of piglets to severe rotavirus diarrhea.