Differences in Processing Determinants of Nonstructural Polyprotein and in the Sequence of Nonstructural Protein 3 Affect Neurovirulence of Semliki Forest Virus.

Unlabelled: The A7(74) strain of Semliki Forest virus (SFV; genus Alphavirus) is avirulent in adult mice, while the L10 strain is virulent in mice of all ages. It has been previously demonstrated that this phenotypic difference is associated with nonstructural protein 3 (nsP3). Consensus clones of L10 (designated SFV6) and A7(74) (designated A774wt) were used to construct a panel of recombinant viruses.