Mixed Infection With Simian Virus 40 and Adenovirus 12

Abstract

Cultures of African green monkey kidney cells were infected simultaneously with simian vacuolating virus (SV40) and human adenovirus 12, two deoxyribonucleic acid viruses with oncogenic activity in Syrian hamsters. After 72 hours' incubation, the cells were studied with the electron microscope. Approximately 50 percent of the cells contained many virus particles morphologically typical of adenoviruses, with no evidence of SV40 particles. About 5 percent contained many SV40 particles but no adenovirus. In about 1 percent of the cells, however, large numbers of particles of both viruses, clearly differing in size and morphology, were intermingled within the same nucleus. When the inoculation of the cultures with adenovirus was delayed for 18.5 or 24 hours after the initial infection with SV40, the number of cells producing both viruses was substantially increased. But if the subsequent inoculation of adenovirus was withheld for 41 hours, a predominance of cells infected with SV40 alone was seen and only a relatively small percentage of cells containing both viruses was found. These observations indicate that mixed infection with SV40 and adenovirus 12 can occur and that variable degrees of partial exclusion may be produced.