Structure of the host-derived sequences present at the 5' ends of influenza virus mRNA

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• Influenza virus gene expression involves transcription of viral RNA into messenger RNA (mRNA).
• The precise mechanisms and sequences involved in the terminal regions of influenza virus mRNA are crucial for understanding viral replication.
• Previous studies suggested complexities in the terminal sequences of viral transcripts.

Purpose of the Study:

• To elucidate the nucleotide sequences at the 5' and 3' termini of the influenza virus matrix (M) gene mRNA.
• To investigate the heterogeneity and non-virus-coded sequences present in the M gene mRNA.
• To determine the precise starting point of transcription for the M gene mRNA.

Main Methods:

• Nucleotide sequence analysis of a cloned matrix gene region from influenza virus.
• Application of the dideoxy-chain termination sequencing method using a restriction fragment.
• Comparison of virion RNA sequences with mRNA sequences.

Main Results:

• The 5' end of the matrix gene mRNA contains an additional 13 non-virus-coded nucleotides.
• A heterogeneous sequence of 9-15 nucleotides was identified at the 5' end of matrix gene mRNAs.
• The 3' terminal nucleotide of the matrix gene virion RNA is not transcribed into mRNA; transcription initiates from the penultimate nucleotide.

Conclusions:

• Influenza virus matrix gene mRNA exhibits significant heterogeneity at its 5' terminus, including non-viral sequences.
• Transcription of the matrix gene mRNA initiates from the penultimate nucleotide of the virion RNA, indicating a specific processing or initiation event.
• These findings provide a detailed understanding of the terminal sequence structure and transcriptional initiation of influenza virus matrix gene mRNA.