Transmission of human leukaemia to nonhuman primates

The experiments described show that inoculation of two monkey species, M. arctoides and P. hamadryas, with human leukaemic blood or its filtrates causes a viral disease with the characteristics of malignant lymphoma of mixed type. The disease was passed in subsequent passages. The virus was isolated and identified as an oncornavirus of C-type by its characteristic morphological appearance and buoyant density (1.16 g/cm3 in sucrose and 1.21 g/cm3 in caesium chloride), and by the presence of 60-70S RNA and RNA-dependent DNA polymerase. There is some evidence that it differs immunologically from other known oncornaviruses of mammals including primates. It is postulated that both horizontal and vertical transmission of this oncornavirus can occur.