Recently, we developed a yeast cell-free system for translation of human papillomavirus (HPV) 58 short L1 mRNA and VLP assembly in vitro. In the present study, we examined the translation efficiency of HPV58 long and short L1 mRNAs in our established system. Production of HPV 58 long and short L1 proteins was significantly dependent on the amounts of the L1 mRNAs used and the time length of translation reaction. Compared with the long L1 mRNA, the short L1 mRNA consistently exhibited higher translation efficiency in all the experiments conducted. Supplementation of exogenous amino acids significantly enhanced translation of the long L1 mRNA in this system. Furthermore, a single amino acid leucine can be rate-limiting for translation of the long L1 mRNA in this system. Electron microscopy demonstrated that HPV 58 virus-like particles (VLPs) were assembled from both long and short L1 capsid proteins in the yeast cell-free system. (C) 2010, The Society for Biotechnology, Japan. All rights reserved.