Strategies to inhibit viral polyprotein cleavages

Picornavirus inhibitors

Picornaviruses are among the best understood animal viruses in molecular terms. A number of important human and animal pathogens are members of the Picornaviridae family. The genome organization, the different steps of picornavirus growth and numerous compounds that have been reported as inhibitors of picornavirus functions are reviewed. The picornavirus particles and several agents that interact with them have been solved at atomic resolution, leading to computer-assisted drug design. Picornavirus inhibitors are useful in aiding a better understanding of picornavirus biology. In addition, some of them are promising therapeutic agents. Clinical efficacy of agents that bind to picornavirus particles has already been demonstrated.

Separation of native and truncated forms of poliovirus protease 3C produced in Escherichia coli

Poliovirus protease 3C is a cysteine enzyme that is essential for the processing of the viral precursor polyprotein containing structural proteins and enzymes, including the protease itself. We have constructed the plasmid pSD/PV3C which produced protease 3C as inclusion bodies when expressed in Escherichia coli. In addition to the full-length protease, a truncated form was also generated, starting from an internal initiation site (Met-27). The enzyme was renatured by dilution of a 6 M guanidinium chloride solution of the inclusion bodies, and the proteins were precipitated from the diluted solution with ammonium sulphate. By extracting the precipitate with a buffer solution, the full-length enzyme could be completely separated from its N-terminally truncated form. Size-exclusion chromatography of the extracted protease 3C resulted in an active enzyme which appeared homogeneous by SDS/PAGE. For measuring the activity of the protease, a spectrofluorimetric method was devised to monitor the hydrolysis continuously, which is simpler and more precise than the h.p.l.c. technique used previously.