AcMNPV EXON0 (AC141) which is required for the efficient egress of budded virus nucleocapsids interacts with β-tubulin

The Autographa californica multiple nucleopolyhedrovirus (AcMNPV) encoded protein, EXON0 (AC141), is required for the efficient transport of nucleocapsids out of the nucleus for the production of budded virus (BV). To further elucidate the molecular mechanisms by which EXON0 regulates BV production, EXON0 was tagged at the N-terminus with 3× FLAG–6× His. Protein complexes were isolated by tandem affinity purification and potential EXON0 specific interacting protein partners were gel purified and identified by LC–MS/MS. This analysis showed that the cellular protein, β-tubulin, co-purified with EXON0 which was confirmed by co-immunoprecipitation. In addition, immunofluorescence showed that EXON0 and β-tubulin co-localized during virus infection. The microtubule inhibitors colchicine and nocodazole were used to treat AcMNPV infected Sf9 cells and results showed that BV production was reduced by over 85%. These data suggest that the egress of AcMNPV budded virus may be facilitated by the interaction of EXON0 with β-tubulin and microtubules.