Introduction to cap-snatching
The first step of transcription for some negative, single-stranded RNA viruses is cap-snatching.
The first 10 to 20 residues of a host cell RNA are removed ("snatched") and used as the 5′ cap and primer to initiate the synthesis of the nascent viral mRNA.
The virus gains two things in this process:
- A 'sense' primer
- A cap that is recognised as 'self' by the host.
Here are some gifs that demonstrate the process!