Filamentous Forms of Enveloped A Particles in Cell Cultures from Chemically Induced Rat Hepatomas¹ Free

A small number of filamentous or cylindrical forms of enveloped A particles was observed in cell cultures established from either a primary or a transplanted rat hepatoma induced in vivo by aromatic amine carcinogens. These same cells produced typical budding particles, enveloped A particles, C particles, and intracisternal A particles. When these cultures were treated with 5-bromo-2-deoxyuridine and/or dimethyl sulfoxide, a striking increase in the total number and percentage of filamentous forms was observed. The length of the filamentous forms was also markedly enhanced by drug treatment, and filaments as long as 1.85 µm were observed. The atypical forms were usually seen budding singly from the cell membrane. Occasionally, however, clusters of these forms were seen associated with the plasma membrane of cells in cultures treated with 5-bromo-2-deoxyuridine and/or dimethyl sulfoxide. Our findings suggest that 5-bromo-2-deoxyuridine and dimethyl sulfoxide, while increasing total virus production in hepatoma cultures, can induce marked aberrations in virus assembly and maturation.