FIG 1.

Diagram of virus and expression vector genomes. (A) Genome structure and genes of unmodified parental alphaviruses. (B) 3′ DP expression virus. (C) nsP3 fusion expression virus. (D) TaV expression virus. (E) Amino acid sequences and restriction enzyme cleavage site positions in the nsP3 protein for reporter insertion in each alphavirus. (F) Structure of reporter insertion site for TaV viruses. Amino acid sequences in the area of the capsid autoprotease site and the sequence of the Thosea asigna virus 2A-like protease are shown. The TaV 2A-like protease “cleaves” nascent proteins by preventing formation of a phosphodiester bond between the carboxy-terminal glycine and proline in the protease sequence (18).