Removal of a N-linked glycosylation site of classical swine fever virus strain Brescia E rns glycoprotein affects virulence in swine

Abstract

E rns glycoprotein, along with E 1 and E 2, is one of the three envelope glycoproteins of classical swine fever virus (CSFV). E rns is a heavily glycosylated protein involved in several functions, including virus attachment and entry to target cells, production of neutralizing antibodies, and virulence. The role of added glycans to CSFV strain Brescia E rns on virus virulence was assessed in swine. A panel of virus mutants was constructed and used to investigate whether the removal of each of seven putative glycosylation sites in the E rns glycoprotein would affect viral virulence in swine. Only N269A/Q substitution rendered attenuated viruses (N1v/N1Qv) that, unlike BICv and other mutants, produced a transient infection in swine characterized by mild symptoms and decreased virus shedding. Notably, N1v efficiently protected swine from challenge with virulent BICv at 3 and 21 days post-infection suggesting that glycosylation of E rns could be modified for development of CSF live-attenuated vaccines.