The Birnaviridae family is comprised of non-enveloped viruses with a double-stranded RNA genome that is divided into two segments, A and B. Birnaviruses are responsible for major economic losses to the poultry and aquaculture industries, and reassortment complicates their epidemiology and control. However, little is known about the nature of theirreplication in cells, or the molecular mechanism underpinning reassortment. In order to address this, we rescued two recombinant infectious bursal disease (IBD) viruses, with either a GFP11 or Tetracysteine (TC) tag at the 3’ end of segment B (IBDV-GFP11 and IBDV-TC, respectively). DF-1 cells were either transfected with GFP1-10 prior to IBDV-GFP11 infection, or stained with ReAsH following IBDV-TC infection, which led to the apprearance of green or red foci in the cytoplasm, respectively. Foci co-localised with VP3 and dsRNA, suggesting these were virus factories (VFs). The average number of VFs significantly decreased from 60 to 5 per cell between 10 and 24 h post infection (P<0.01), while the average area significantly increased from 1.24 µm to 45.01 µm (P<0.01), suggesting VFs coalesce in the cytoplasm over time. Red, green and yellow foci were observed in the cytoplasm of co-infected cells, suggesting that VFs are initially derived from distinct input viruses prior to coalescence. Live cell imaging revealed that larger VFs were more static while smaller VFs were more mobile, and fusion events were observed. We speculate that VF coalescence is required for birnavirus reassortment, and current work is aimed at determining the cellular factors that drive coalescence.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error