Alteration of the N-linked Glycosylation Condition of E1 Glycoprotein of Classical Swine Fever Virus Strain Brescia Alters Virulence in Swine

Authors: FERNANDEZ-SAINZ, IGNACIO - ORISE, USDA, ARS, FELLOW; Holinka-Patterson, Lauren; GAVRILOV, B. - UNIV CONNECTICUT STORRS; Prarat, Melanie; Gladue, Douglas; LU, Z. - DHS, S&T, PIADC; JIA, W. - USDA, APHIS, PIADC; RISATTI, GUILLERMO - UNIV CONNECTICUT STORRS; Borca, Manuel

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2008
Publication Date: 2/8/2009
Citation: Fernandez-Sainz, I.J., Holinka-Patterson, L.G., Gavrilov, B.K., Prarat, M.V., Gladue, D.P., Lu, Z., Jia, W., Risatti, G.R., Borca, M.V. 2009. Alteration of the N-linked Glycosylation Condition of E1 Glycoprotein of Classical Swine Fever Virus Strain Brescia Alters Virulence in Swine. Virology. 386:210-216.

Interpretive Summary: Classical Swine Fever Virus (CSFV) has proteins that mediate entry into the cells to cause infection and disease in swine. One of these proteins called E1 has been involved in virus attachment and entry to target cells during the infection as well as the process of producing disease in pigs. E1 is glycosylated, meaning that it has sugar molecules attached to it. The role of this glycosylation in the biology of the CSFV is unknown. In this report we specifically analyzed the function of the glycosylation of E1 in the capacity of the virus to induce disease in swine. We showed that viruses lacking glycosylation in E1 did not cause disease in swine but induced a strong immune response and therefore could be used as potential vaccines. Swine immunized with these E1 mutants were protected against disease as early as 3 days after vaccination. Thus these viruses could potentially be used to develop new vaccines against CSFV.

Technical Abstract: E1, along with Erns and E2 is one of the three envelope glycoproteins of Classical Swine Fever Virus (CSFV). Previously we showed that glycosylation status of virulent CSFV strain Brescia E2 or Erns affects virus virulence. Here, the three putative glycosylation sites of E1 were serially removed by means of site directed mutagenesis of a CSFV Brescia infectious clone (BICv) and their effect on virulence assessed in swine. While removal of all three putative glycosylation sites in E1 yielded non viable progeny, single or dual site mutants were viable. Individual N594A (E1.N3 virus) or combined N500A/N513A (E1.N1N2 virus) substitutions resulted in BICv attenuation. Furthermore infection with E1.N3 or E1.N1N2 viruses efficiently protected swine from challenge with virulent BICv at 3 and 28 days post-infection. As previously observed with Erns and E2 and here with E1 data suggest that modification of glycosylation patterns could be used for developing CSFV live-attenuated vaccines.