Properties of cells with increased resistance to some picornaviruses

The resistance to picornaviral infection cells of susceptible lines has similar changes in the phenotype. They have decreased number of nucleoli and increased percentage of euploidy. Also the percentage of euploid cells those were resistant to the picornaviral infection increased in all highly transformed cultures. In resistant cells of all cultures has been found reduction of DNA. RNA amount also decreased both in nucleus and in cytoplasm. All these data correlated with the increased euploidy of the resistant population. The resistant cells had a less transformed phenotype, and decreased proliferative activity. Decreased nucleolar status became apparent by reduction of absolute and relative nucleolar indices. Consequently the reduction of viral titer (viral titters reduction) in resistant cells could be the direct result of diminished activity of the RNA synthesis machinery. It is important to note that the cells lose resistance while another type of virus, even from the same family, infects the culture once.