Novel replication-competent reporter-expressing Rift Valley fever viruses for molecular studies

Area of Science:

• Virology
• Molecular Biology
• Public Health

Background:

• Rift Valley fever virus (RVFV) is a mosquito-borne zoonotic disease posing significant risks to livestock and human health.
• Current detection methods for RVFV require secondary techniques, highlighting a need for improved diagnostic tools.
• The RVFV genome comprises three RNA segments (S, M, L), with Segment S encoding nucleoprotein (N) and non-structural (NSs) proteins.

Purpose of the Study:

• To develop novel recombinant (r)RVFV strains capable of reporting viral presence using reporter genes.
• To investigate the genome plasticity of RVFV by modifying Segment S to incorporate reporter genes.
• To establish a tool for tracking RVFV infection and evaluating antiviral strategies.

Main Methods:

• Utilized T7-driven polymerase plasmid-based reverse genetics to generate rRVFV.
• Introduced Nanoluciferase (Nluc) or Venus fluorescent proteins into the RVFV genome, primarily modifying Segment S.
• Compared four strategies for reporter gene insertion and assessed viral stability and replication.

Main Results:

• Generated stable, replication-competent rRVFV expressing Nluc or Venus fluorescent proteins.
• Demonstrated successful tracking of RVFV in mammalian and insect cells using reporter genes.
• Validated rRVFV for identifying neutralizing antibodies and antiviral compounds, showing attenuated phenotypes in a mouse model.

Conclusions:

• Reporter-expressing rRVFV provide a valuable tool for studying RVFV biology and pathogenesis.
• These recombinant viruses can be used to screen for and validate antiviral therapeutics.
• The developed rRVFV strains offer a promising platform for advancing RVFV vaccine development and diagnostics.