Stable Alphavirus Packaging Cell Lines for Sindbis Virus-and Semliki Forest Virus-Derived Vectors

• Published in: Proceedings of the National Academy of Sciences - PNAS 1999-04, Vol.96 (8), p.4598-4603
• Main Authors: Polo, John M., Belli, Barbara A., Driver, David A., Frolov, Ilya, Sherrill, Scott, Hariharan, Mangala J., Townsend, Kay, Perri, Silvia, Mento, Steven J., Jolly, Douglas J., Stephen M. W. Chang, Schlesinger, Sondra, Dubensky, Thomas W.
• Format: Article
• Language: English
• Subjects: Alphavirus - genetics; Alphaviruses; Animals; Antibody Formation; Biological Sciences; Cell Line; Cell lines; Cell Transformation, Viral; Cricetinae; Female; Gene therapy; Genes; Genetic Vectors; Glycoproteins; Humans; Infections; Kidney; Mice; Mice, Inbred BALB C; Packaging; Promoter Regions, Genetic; Protein Biosynthesis; Ribonucleic acid; RNA; RNA, Messenger - genetics; RNA, Viral - genetics; Semliki Forest virus; Semliki forest virus - genetics; Sindbis Virus; Sindbis Virus - genetics; T-Lymphocytes, Cytotoxic - immunology; Transcription, Genetic; Vaccines; Vaccines, Synthetic; Viral Structural Proteins - biosynthesis; Viral Structural Proteins - genetics; Viral Structural Proteins - immunology; Viral Vaccines; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.8.4598

Alphavirus vectors are being developed for possible human vaccine and gene therapy applications. We have sought to advance this field by devising DNA-based vectors and approaches for the production of recombinant vector particles. In this work, we generated a panel of alpha-virus vector packaging cell lines (PCLs). These cell lines were stably transformed with expression cassettes that constitutively produced RNA transcripts encoding the Sindbis virus structural proteins under the regulation of their native subgenomic RNA promoter. As such, translation of the structural proteins was highly inducible and was detected only after synthesis of an authentic subgenomic mRNA by the vector-encoded replicase proteins. Efficient production of biologically active vector particles occurred after introduction of Sindbis virus vectors into the PCLs. In one configuration, the capsid and envelope glycoproteins were separated into distinct cassettes, resulting in vector packaging levels of107infectious units/ml, but reducing the generation of contaminating replication-competent virus below the limit of detection. Vector particle seed stocks could be amplified after low multiplicity of infection of PCLs, again without generating replication-competent virus, suggesting utility for production of largescale vector preparations. Furthermore, both Sindbis virus-based and Semliki Forest virus-based vectors could be packaged with similar efficiency, indicating the possibility of developing a single PCL for use with multiple alphavirus-derived vectors.