Polyomaviruses are nonenveloped viruses with capsids composed primarily of 72 pentamers of the viral VP1 protein, which forms the outer shell of the capsid and binds to cell surface oligosaccharide receptors. Highly conserved VP1 proteins from closely related polyomaviruses recognize different oligosaccharides. To determine whether @entity535 changes restricted to the oligosaccharide binding site are sufficient to determine receptor specificity and how changes in receptor usage affect tropism, we studied the primate polyomavirus @entity2235 (SV40), which uses the @entity10643 as a receptor that mediates cell binding and entry. Here, we used two sequential genetic screens to isolate and characterize viable SV40 mutants with mutations in the VP1 GM1 binding site. Two of these mutants were completely resistant to GM1 neutralization, were no longer stimulated by incorporation of GM1 into cell membranes, and were unable to bind to GM1 on the cell surface. In addition, these mutant viruses displayed an @entity281 defect in monkey cells with high levels of cell surface GM1. Interestingly, one mutant infected cells with low cell surface GM1 more efficiently than wild-type virus, apparently by utilizing a different @entity4163 receptor. Our results indicate that a small number of mutations in the GM1 binding site are sufficient to alter @entity4163 usage and change tropism, and they suggest that VP1 divergence is driven primarily by a requirement to accommodate specific receptors. In addition, our results suggest that GM1 binding is required for vacuole formation in permissive monkey CV-1 cells. Further study of these mutants will provide new insight into polyomavirus entry, pathogenesis, and evolution.

Mutations in the GM1 binding site of XXXX VP1 alter receptor usage and cell tropism.

@entity2235 :: ('10633', 'Species') :: ['simian virus 40'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity281 :: ('MESH:D007239', 'Disease') :: ['infection'] @entity10643 :: ('MESH:D005677', 'Chemical') :: ['ganglioside GM1'] @entity4163 :: ('CHEBI:28892', 'Chemical') :: ['ganglioside']
@entity2235 :: (10633,Species) :: ['simian virus 40']
