RNA Interference Restricts Rift Valley Fever Virus in Multiple Insect Systems

Area of Science:

• Molecular Biology
• Virology
• Immunology

Background:

• Rift Valley fever virus (RVFV) is an emerging zoonotic pathogen transmitted by mosquitoes.
• RNA interference (RNAi) is an innate immune mechanism in insects against viruses, but its role against negative-strand RNA viruses like RVFV is poorly understood.
• Understanding RVFV-vector interactions is crucial for controlling transmission and preventing disease.

Purpose of the Study:

• To investigate the role of antiviral RNA interference (RNAi) pathways in natural RVFV vector mosquitoes.
• To compare RVFV-induced RNAi responses in mosquito cells, Drosophila melanogaster, and vector mosquitoes.
• To determine if RVFV encodes RNAi suppressors.

Main Methods:

• Analysis of small RNAs in infected mosquito cells, Drosophila melanogaster, and adult Aedes sp. and Culex quinquefasciatus mosquitoes.
• Detection of virus-derived Piwi-interacting RNAs (piRNAs) and exogenous small interfering RNAs (siRNAs).
• Assessment of antiviral activity by silencing RNAi pathway effectors and observing viral replication.

Main Results:

• Virus-specific small RNAs, including piRNAs and siRNAs, are produced in response to RVFV infection in various insect models and natural vectors.
• Virus-derived piRNAs were detected in both Aedes sp. and Culex quinquefasciatus mosquitoes.
• Silencing RNAi pathway components enhanced RVFV replication, confirming the antiviral activity of RNAi.
• RVFV does not appear to encode an RNAi suppressor.

Conclusions:

• RNA interference plays a significant role in controlling Rift Valley fever virus replication in mosquitoes.
• Both exogenous siRNA and piRNA pathways contribute to antiviral defense against RVFV.
• The findings highlight the potential for developing novel RVFV control strategies targeting RNAi pathways in mosquito vectors.