RELATIONSHIP BETWEEN CELL-GROWTH AND VIRAL-ANTIGEN CONTENT OF CULTURES OF NICOTIANA-TABACUM INOCULATED WITH TOBACCO MOSAIC-VIRUS

Cell suspension cultures of Nicotiana tabacum (cv. White Burley) were inoculated with TMV (type strain) by coincubation. Infection of the cells occurred over the 24 h period following inoculation. Over the interval 2-6 d following inoculation, which corresponded to the period of mitotic activity of the cultures, the viral antigen and infectivity of the cultures declined. The results suggest a link between host cell division and lass of virus from the cells. This decline was accompanied by the appearance in the culture extracts of virus rods of less than normal (300 nm) length, and an overall reduction in the total number of virus particles per field under the electron microscope. These observations suggested that the loss of infectivity of the extracts resulted, at least in part, from disruption of the virus. After the end of the period of mitosis, the cultures showed a second phase of antigen accumulation. However, the infectivity of the extracts continued to decrease to zero over the same period and the proportion of shortened virus rods increased. Infection by TMV altered the growth of the tobacco cells. Over the first 6 d following inoculation, the growth rate was reduced, whereas following day 6, the growth rate of inoculated cultures was higher than uninfected controls.