Association of nuclear matrix proteins with cytoplasmic assembly sites of Tipula iridescent virus.

Intact viroplasmic centers were isolated from Estigmene acres cells infected with Tipula iridescent virus (TIV) by homogenization, followed by differential and discontinuous sucrose gradient centrifugation. Labeling of in situ and isolated viral assembly sites by two monoclonal antibodies raised against lymphocyte nuclear matrix proteins indicated a possible involvement of highly conserved nuclear proteins in the assembly and maturation of virions, as well as in maintaining the integrity of membrane-free viroplasmic centres. Electron microscopy and immunofluorescence of intact and fractionated E. acrea cells at different times postinfection showed no evidence of cytoskeleton involvement in the formation and maintenance of TIV viroplasmic centers.