Effects of deletion of MIT domains of host Vta1 on replication of Autographa californica multiple nucleopolyhedrovirus.
: [Objective] To isolate Vta1 of Spodoptera frugiperda and to detect the requirement of Vta1 in replication of Autographa californica multiple nucleopolyhedrovirus (AcMNPV). [Methods] Vta1 was isolated from Sf9 cells using reverse-transcription PCR. Two mutations of Vta1, which removed the first or second microtubule-interacting and transport domain (MIT) were transiently expressed. The interaction of Vta1 and its mutants with Vps4, Vps46 and Vps60 was detected with bimolecular fluorescence complementation (BiFC). Using a viral complementation assay, the effect of Vta1 mutants on replication of AcMNPV was determined. [Results] We obtained Vta1 of S. frugiperda. The amino acid identities between Vta1 of insect and yeast or between Vta1 of insect and human were about 20% or 50%. Western blotting analysis showed GFP-tagged Vta1 and its mutants were expressed in Sf9 cells. BiFC analysis revealed that deletion of MIT1 or MIT2 significantly reduced the interaction of Vta1 mutants with Vps4, Vps46 or Vps60. Overexpression of Vta1 mutants significantly decreased the infectious AcMNPV budded virions production but had no effect on the expression of the reporter genes LacZ and GUS, which separately controlled by AcMNPV ie1 and p6.9 early or late promoter. [Conclusion] Vta1 might be involved in assembly and/or budding of progeny virions of AcMNPV.