RPS3 and infection: However, while thin-section electron micrographs of PEVs in cells infected with a US3-null PrV mutant showed them to be morphologically similar to the rarer PEVs observed in a wild-type infection (33) and to PEVs seen in gB/gH null infections (34), it remains possible that wild-type PEVs differ from US3-null PEVs in certain respects, including molecular composition.