INTERACTION OF ASSEMBLED PROGENY POX VIRUSES WITH THE CELLULAR CYTOSKELETON

Chick embryo fibroblasts infected with vaccinia WR or cowpox virus were studied by immunofluorescence and electron microscopy. Both techniques indicate an intimate association of mature progeny virus with the actin-containing microfilaments of the cellular cytoskeleton. Late in infection cells display specialized microvilli-type structures which contain a core of microfilaments with a virus particle at their tip. Of the proteins usually found associated with actin in cellular microfilaments (tropomyosin, myosin, and α-actinin) only α-actinin could be positively identified as associated with the array of actin filaments within these pox virus-induced microvilli. These specialized microvilli can easily be distinguished from normal cellular microvilli because they are nearly threefold larger in diameter, the width necessary to accomodate a pox virion. Inhibition of virus assembly prevents the induction of the specialized microvilli, thus indicating that mature viruses, or a factor present only under such conditions, induce their formation. In addition to virus particles found in microvilli, numerous other mature virions are observed connected to the microfilamentous structure which lie close to the plasma membrane. © 1979.