A reverse-genetics system for Influenza A virus using T7 RNA polymerase

Area of Science:

• Virology
• Molecular Biology

Background:

• Current Influenza A virus reverse-genetics systems rely on RNA polymerase I, which has species-specific limitations.
• Developing adaptable reverse-genetics systems is crucial for influenza research and vaccine production.

Purpose of the Study:

• To develop and optimize a novel reverse-genetics system for Influenza A virus rescue.
• To overcome the limitations of existing RNA polymerase I-based systems.

Main Methods:

• A new vector was engineered incorporating a T7 RNA polymerase promoter, hepatitis delta virus ribozyme, and T7 terminator.
• Optimization involved determining optimal viral RNA insertion orientation and promoter modifications (two additional G residues).
• The use of T7 RNA polymerase with a nuclear-localization signal was investigated for enhanced minigenome expression.

Main Results:

• The novel system demonstrated more efficient production of recombinant Influenza A virus (A/PR/8/34) compared to polymerase I systems.
• Influenza A virus (A/NL/219/03) rescue was successfully achieved in 293T, MDCK, and QT6 cell lines.
• Optimized conditions, including RNA orientation and promoter elements, significantly improved minigenome expression.

Conclusions:

• A versatile reverse-genetics system for Influenza A virus rescue has been successfully developed.
• This system offers advantages over existing methods, including broader cell line compatibility.
• The developed system is valuable for both fundamental influenza virus research and the production of vaccine seed strains.