Variation I N T H E Oncogenic Potential of Human Adenoviruses

The biological properties of a human adenovims that has incorporated defective SV40 genetic material within its adenocapsid have been extensively studied (1, 2). The particle containing the defective SV40 genome is known as PARA (2). Its presence confers new properties on the adenovirus population which now replicates in simian cells (3), carries the genetic information for the synthesis of SV40 tumor (T) antigen (4, 5) and SV40 specific transplantation antigens (6), and is oncogenic in newborn hamsters (1, 7). Genetic material from PARA can be transferred to other human adenovimses by a process called transcapsidation (8, 9). As a result of such transfer to type 2, this previously nononcogenic adenovirus produced tumors when injected into newborn hamsters (7, 10). These tumors were characteristic of either SV40-induced tumors, adenovirus-like tumors, or contained elements of both types. Hamster cells transformed in vitro by PARA-adenovirus 2 yielded similar tumors when inoculated into weanling hamsters (11).