Abstract: Parasite genes often use codons which are rarely used in Eschericha coli,possibly resulting lower protein yields of recombinant protein.RIG plasmid contains the genes encode several rare tRNAs.When co-transformed into E. coli with expression plasmid containing gene coding human mitochondial transcript terminator liked protein,RIG can greatly increase levels of overexpressed protein.RIG is a good solution for codon bias.