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 GM₃ 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 10⁴ 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.