Cytogenetic Studies of Hamster Kidney Cell Cultures Transformed by the Simian Vacuolating Virus (SV40)2

Cytogenetic studies were performed on transformed cell cultures arising from hamster kidney cell monolayers infected with the simian vacuolating virus (SV40). After a 3- to 6-week latent period, colonies of rapidly growing cells emerged from infected cultures. The earliest cells in these cultures appeared to have chromosome numbers in the diploid range, with frequent chromosomal aberrations such as breaks, translocations, and deletions. These cells were rapidly overgrown by those with chromosome numbers in the range between triploid and tetraploid during serial passage. There was a constant tendency for the production of cells with greater numbers of chromosomes. The separation of the chromosomes at metaphase into discrete clusters was an unusual tendency. Karyotype analysis revealed irregular replication of different groups of chromosomes without the presence of a unique stemline. Abnormal chromosomes were present in many cells. It is concluded that SV40 produces a biochemical growth stimulus on which are superimposed processes producing aneuploidy.