Influenza A virus preferentially snatches noncoding RNA caps

Area of Science:

• Virology
• Molecular Biology
• RNA Biology

Background:

• Influenza A virus (IAV) requires host-capped RNA fragments for transcription initiation via cap-snatching.
• Previous studies lacked comprehensive analysis of noncoding RNAs and promoter-associated capped small (cs)RNAs as IAV targets.
• The precise host RNA preferences and functional impact of IAV cap-snatching remain incompletely understood.

Purpose of the Study:

• To identify host and viral-capped RNAs, including nonpolyadenylated RNAs, using a nonbiased method.
• To investigate the correlation between host RNA substrates and viral RNA products in IAV infection.
• To determine the preference of IAV cap-snatching for different host RNA classes.

Main Methods:

• Utilized CapSeq, a nonbiased technique, to profile host and viral-capped RNAs from infected cells.
• Analyzed substrate-product relationships between host RNAs and viral RNAs.
• Compared the snatching preference of IAV for noncoding RNAs versus messenger RNAs (mRNAs) and pre-mRNAs.

Main Results:

• Demonstrated that noncoding host RNAs, specifically U1 and U2 snRNAs, are preferred targets for IAV cap-snatching over mRNAs.
• Identified promoter-associated capped small (cs)RNAs as highly snatched by IAV.
• Established a substrate-product correlation between host RNAs and viral RNAs.

Conclusions:

• IAV preferentially targets nascent noncoding RNAs, including U1, U2, and csRNAs, for cap-snatching.
• Findings suggest csRNAs play a role in IAV infection, despite their largely unknown functions.
• Raises questions about IAV's modulation of host mRNA splicing and transcription through selective cap-snatching.