Alterations of actin-containing structures in BHK21 cells infected with Newcastle disease virus and vesicular stomatitis virus.

The distribution pattern of actin-containing structures in BHK21 cells and the changes which they undergo upon infection with Newcastle disease virus (NDV) and vesicular stomatitis virus (VSV) were studied by means of immunofluorescence. Double labelling with antibodies conjugated with fluorescein (for actin) and rhodamine (for virus antigens) has shown that the progressive cytopathic effects after virus infection are accompanied by extensive alterations of the structures demonstrable by antiactin antibodies. In NDV-infected BHK21 cells the number of actin filaments increases, some zones which contain virus antigens apparently being in close association with the actin structures. By contrast, infection with VSV results in a strong reduction of actin-containing fibres. The results indicate that in the genesis of morphologically detectable alterations of a cell after virus infection--the 'cytopathic changes'--alterations of those structural elements are involved which are also probably responsible for maintenance of cell shape and motility.