Patent Evaluation: DNA Expression Systems Based on Alphaviruses

Summary

Novelty: A novel expression system based on the animal alphavirus is disclosed. This expression system is said to offer both simplicity and safety in terms of handling and protein production, as well as a broad host range. The modified viral expression system has particular utility in the production of chimaeric virus particles or recombinant viruses for protein production.

Biology: A modified positive-stranded alphavirus, Semliki Forest virus (SFV), was used for the expression vector. The SFV cDNA was ligated into a plasmid and placed downstream of an SP6 RNA polymerase promoter. Further modifications included deletion of the viral cDNA sequences encoding structural proteins and the insertion of a polylinker sequence. An alternative construction utilizes a full-length cDNA sequence where an exogenous DNA fragment encoding an epitopic peptide can be inserted in a region encoding the viral structural protein.