Technologies

Recombinant, infectious influenza viruses can be used as vaccine and gene therapy vectors; however, producing influenza virus particles is difficult because the influenza genome consists of negative-sense RNA molecules that cannot directly serve as templates in protein synthesis. Virus production normally requires a helper virus that provides needed structural proteins and polymerases. UW-Madison resarchers have developed an improved reverse genetics system for producing influenza virus in vertebrate cells in the absence of helper virus. The system starts with a set of plasmids containing viral genome cDNAs flanked by ribozymes. Each plasmid carries a cDNA for one of the eight influenza A viral RNA segments. On each plasmid, the cDNA sits between a polymerase II promoter and a poly-A addition signal at the 3-prime end. When the plasmids are transfected into a vertebrate cell, the host cell’s RNA polymerase II transcribes each construct into a capped viral RNA with a proper poly-A tail. The flanking ribozyme RNAs then undergo site-specific, self-catalyzed cleavage to precisely trim each end of the viral RNA. Next, viral polymerase, which is provided by a protein expression plasmid, acts upon the viral RNAs, resulting in replication and mRNA synthesis. This system does not require a helper virus and allows the creation of transfectants with mutations in any gene segment.

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing an improved reverse genetics system for producing influenza virus in vertebrate cells in the absence of helper virus.