Controlling Classical Swine Fever Virus (CSFV) involves either prophylactic vaccination or non-vaccination and elimination of infected herds depending on the epidemiological situation. Marker vaccines allowing distinction between naturally infected from vaccinated swine could complement "stamping out" measures. Previously, we reported the development of FlagT4v, a double antigenic marker live attenuated CSFV strain. FlagT4v was later shown as not to be completely stable in terms of its attenuation when assessed in a reversion to virulence protocol. We have developed a modified version of the FlagT4v where changes in the codon usage of genomic areas encoding for Flag and T4 were introduced to rectify the reversion to the virulent genotype. The new virus, FlagT4-mFT-Gv, possesses the same amino acid sequence as FlagT4v except for one substitution, Asparagine is replaced by Glycine at position 852 of the CSFV polypeptide. FlagT4-mFT-Gv protected swine against challenge with Brescia virulent virus at 21 days post vaccination.

The United States of America, as Represented by the Secretary of Agriculture

The University of Connecticut

The United States of America as represented by The Secretary of Agriculture

The University of Conneticut

Live attenuated antigenically marked classical swine fever vaccine

E2 is one of the three envelope glycoproteins of Classical Swine Fever Virus (CSFV). E2 is involved in several functions including virus attachment and entry to target cells, production of antibodies, induction of protective immune response in swine, and virulence. Seven putative glycosylation sites in E2 were modified by site directed mutagenesis of a CSFV Brescia infectious clone (BICv). A panel of virus mutants was obtained and used to investigate whether the removal of putative glycosylation sites in the E2 glycoprotein would affect viral virulence/pathogenesis in swine. We observed that rescue of viable virus was completely impaired by removal of all putative glycosylation sites in E2, but restored when mutation N185A reverted to wild-type asparagine produced viable virus that was attenuated in swine. Single mutations of each of the E2 glycosylation sites showed that amino acid N116 (N1v virus) was responsible for BICv attenuation. N1v efficiently protected swine from challenge with virulent BICv at 3 and 28 days post-infection suggesting that glycosylation of E2 could be modified for development of CSF live-attenuated vaccines. Additionally, a new developed virus, contained deletions of putative glycosylation sites N1 in E2 and N1 in E0 (6b), called N1E0/2v, induce a solid protection against the challenge at 3 and 28 days post-inoculation.

Borca; Manuel

Risatti; Guillermo

The United States of America, as represented by the Secretary of Agriculture

N-linked glycosylation alteration in E0 and E2 glycoprotein of classical swine fever virus and novel classical swine fever virus vaccine

asparagine

palavik

fever

asparagine/palavik

Live attenuated antigenically marked classical swine fever vaccine

N-linked glycosylation alteration in E0 and E2 glycoprotein of classical swine fever virus and novel classical swine fever virus vaccine

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