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(3) 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 NeuGcGM(3) (50% inhibition with 3.97 nmol) or NeuAcGM(3) (50% inhibition with 9.84 nmol) per 10(4) FFU of virus. Preliminary data suggest specific porcine GM(3) carbohydrate fine structure or spatial orientation of the sialyloligosaccharide epitopes of the holoGM(3) gangliosides may be crucial to enterocyte receptor recognition by rotavirus. We have quantified both NeuGcGM(3) and NeuAcGM(3) in enterocytes of various-aged pigs from newborn through 16 weeks and have found with increasing age the amount of both GM(3) derivatives, especially NeuGcGM(3) 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.