PT  - JOURNAL ARTICLE
AU  - Sereina O. Sutter
AU  - Anouk Lkharrazi
AU  - Elisabeth M. Schraner
AU  - Kevin Michaelsen
AU  - Anita Felicitas Meier
AU  - Bernd Vogt
AU  - Hildegard Büning
AU  - Cornel Fraefel
TI  - Adeno-associated virus type 2 (AAV2) uncoating is a stepwise process and is linked to structural reorganization of the nucleolus
AID  - 10.1101/2021.12.13.472349
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.12.13.472349
4099  - http://biorxiv.org/content/early/2021/12/13/2021.12.13.472349.short
4100  - http://biorxiv.org/content/early/2021/12/13/2021.12.13.472349.full
AB  - Nucleoli are membrane-less structures located within the nucleus and are known to be involved in many cellular functions, including stress response and cell cycle regulation. Besides, many viruses can employ the nucleolus or nucleolar proteins to promote different steps of their life cycle such as replication, transcription and assembly. While adeno-associated virus type 2 (AAV2) capsids have previously been reported to enter the host cell nucleus and accumulate in the nucleolus, both the role of the nucleolus in AAV2 infection, and the viral uncoating mechanism remain elusive. In all prior studies on AAV uncoating, viral capsids and viral genomes were not directly correlated on the single cell level, at least not in absence of a helper virus. To elucidate the properties of the nucleolus during AAV2 infection and to assess viral uncoating on a single cell level, we combined immunofluorescence analysis for detection of intact AAV2 capsids and capsid proteins with fluorescence in situ hybridization for detection of AAV2 genomes. The results of our experiments provide evidence that uncoating of AAV2 particles occurs in a stepwise process that is completed in the nucleolus and supported by alteration of the nucleolar structure.Author Summary Adeno-associated virus (AAV) capsids have been reported to enter the host cell nucleus and accumulate in the nucleolus. However, both the role of the nucleolus in AAV2 infection as well as the viral uncoating mechanism remain unknown. Here, we provide evidence that uncoating of the AAV2 particle is a stepwise process that is completed in the nucleolus and supported by alteration of the nucleolar morphology.Competing Interest StatementThe authors have declared no competing interest.