Internal viral RNA sequences of the PB2 genome segment of influenza A virus are required for efficient generation of fully infectious particles

Abstract: The genome of influenza A virus is divided into eight unique single-stranded viral RNA (vRNA) segments, each of which comprises a central coding region flanked by short 3’ and 5’ non-coding regions (NCR). To be fully-infectious, influenza A virions must package one copy of each genome segment. RNA domains that trigger specific RNA-RNA interactions among the segmented genome, designated as packaging signals, are thought to ensure the packaging process. In previous experiments, such packaging signals have been mapped to the segment termini, including the NCR and various portions of the adjacent coding region. However, recent studies suggest that besides these terminal packaging signals, internally located RNA regions might also be crucial for the assembly of fully-infectious virions.
To examine the effect of internal vRNA sequences of the PB2 genome segment on the packaging process, several PB2-GFP reporter as well as PB2-linker segments were generated. In these segments, internal PB2 vRNA regions of varying size were replaced by either a GFP gene or 49 random linking nucleotides (nt). The resulting segments harbored the NCR plus 120 to 780 nt of both coding region ends, thus comprising the previously defined terminal packaging signals and, potentially, also internal packaging regions. In reverse genetics experiments, short linker segments containing 120, 240 or 360 nt of the coding region did not allow the formation of infectious particles. An elongation up to 480 nt partially repaired this defect. In contrast, PB2-linker viruses harboring 600, 720 or 780 nt of the coding region at each end displayed coordinated genome packaging. In particles of the latter viruses, a truncated PB2 vRNA derived from the PB2(780) linker segment was found. However, serial passaging at low multiplicity in a PB2-expressing cell line did not result in its enrichment. These data may suggest, that these short PB2 vRNAs fail to package the remaining seven genome segments, possible due to the lack of specific internal packaging signals that are present in linker vRNAs. Another possibility may be that the function of the terminal packaging signals requires a minimal length of the viral genome segment. In line with this, PB2-GFP reporter segments harboring identical PB2 vRNA nucleotide sets as the short linker segments were partially packaged into fully-infectious virus particles. Together, these findings highlight the importance of internal regions of the PB2 genome segment for the generation of fully infectious particles and provide first functional insights into the mechanism of defective interfering vRNAs harboring large internal deletions

Objekt anzeigen

• Standort: Deutsche Nationalbibliothek Frankfurt am Main
• Umfang: Online-Ressource
• Sprache: Englisch
• Anmerkungen: Universität Freiburg, Dissertation, 2021

Klassifikation und Themen

• Schlagwort: Influenza ; Particles ; Influenza-A-Virus

Beteiligte, Orts- und Zeitangaben

• Ereignis: Veröffentlichung
• (wo): Freiburg
• (wer): Universität
• (wann): 2021
• Urheber: Feder, Fleur Isabel
• Beteiligte Personen und Organisationen: Schwemmle, Martin ; Thimme, Robert ; Albert-Ludwigs-Universität Freiburg. Medizinische Fakultät

Weitere Informationen

• DOI: 10.6094/UNIFR/219086
• URN: urn:nbn:de:bsz:25-freidok-2190863
• Rechteinformation: Kein Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.