Conditions resulting in formation of properly assembled retroviral capsidswithin inclusion bodies of Escherichia coli

It has been generally accepted that inclusion bodies (IBs) formed in Escher ichia coli consist of non-biologically active aggregated proteins, which ar e stabilized by non-productive interactions. We show here that bacterial ex pression of a retroviral capsid polyprotein results in formation of insolub le IBs that contain fully assembled viral particles connected with amorphou s material. The efficiency of IBs formation and capsid assembly was not sig nificantly affected by changes in induction temperature, pH of cultivation medium or the level of expression.