[Progress on development and research of coronavirus based vector].

Due to the progress of targeted recombination and reverse genetics technique, it is possible to express foreign genes using coronaviruses as a vector via its unique transcription mechanism. Two types of coronavirus-based expression vectors have been developed; one is helper-dependent expression system and the other a single genome-based expression system. By modification of the infectious cDNA of the genome of coronaviruse, it has led to an efficient (> 50 microg/10(6)cells) and stable (> 30 passages) expression of the foreign gene. Moreover,several other features of coronavirus make it attractive as a vector. Firstly, the virulent coronaviruse can be converted into nonvirulent viruse by deleting the nonessential, group-specific genes. Secondly, the species and tissue tropism of coronaviruses can be manipulated by modification of their attachment and fusion protein S. Thus, coronavirus-based vector is becoming a promising and useful tool for vaccine development and gene delivery.