Factors Influencing Tumor Induction in Hamsters by Vacuolating Virus, SV40.

Abstract

The vacuolating agent, SV40, was first discovered as an indigenous contaminant of primary cell cultures of rhesus and cynomolgus fied at 2000 rpm for 20 minutes in the horizontal centrifuge. The supernate used in the animal experiments titered 1 k 6 per 0.2 ml in monkey kidney and of oral poliovirus vaccine ( 1,2). Subsequent findings revealed an oncogenic quality of the virus with induction of fibrosarcomatous neoplasms and ependymomas(3-5) in newborn hamsters and of papillary ependymomas (6) in newborn Mastomys. The oncogenic quality of the virus has become more understandable in the recent demonstration of its close biologic relationship to other tumorigenic agents including papilloma viruses of man and rabbits and of the mouse polyoma agent ( 7 ) . The virus produces subclinical infection in human subjects following respiratory inoculation or oral ingestion and is excreted into the feces subsequent to inoculation by the latter route (8,9). In primary embryonic, neonatal or adult human cells in culture, the virus causes epithelioid transformation with consistent chromosomal aberration of a probable heritable nature ( 10-13).The importance of SV40 virus as a malignant oncogenic agent prompted descriptive studies of the pathogenesis of the virus in the hamster model. The present report presents findings in investigations to measure the effect of host age, virus dose, and route of inoculation on oncogenic efficiency and to ascertain the transmissibility of the agent by contact.Materials and methods. The detailed methods described previously (3) were generally followed. Virus strain VA 45-54 derived from uninoculated grivet monkey kidney (GMK) cell culture was used. Virus in first subculture passage was employed and exhaustive tests revealed that Sv40 was the only detectable agent present. The infected cell cultures were frozen and thawed several times at time of harvest and the virus pool was clari-*This work was supported in part by grant from U. S. Public Health Service. GMK cell cultures (10 day reading) and was stored frozen in flame-sealed glass ampules in the dry ice refrigerator. Control tissue culture fluid (NTCF) was prepared in similar manner from uninoculated cell cultures of the same lot of GMK and was stored as described above. Control medium (CM), composed of medium 199 containing 2 70 of heat-inactivated chicken serum, p H 7.0, was the same lot used for maintenance of the cell cultures described above and was stored in similar fashion. Hamsters were from the Lakeview Hamster Colony, Lakeview, N. J., and were inoculated when newborn or 7 , 30 or 90 days of age. The virus dose was 0.2 ml given subcutaneously unless otherwise indicated. The virus was titrated for infectivity in GMK each time it was used. When diluted for hamster inoculation, medium CM was employed. Animal care, clinical observations, and pathologic examinations were as described previously. Serology. Hamster sera were tested for neutralizing antibody using 30-300 TCDS0 of strain 45-54 of SV4, virus. The sera were inactivated at 56°C f...

Some Oral Poliovirus Vaccines Were Contaminated with Infectious SV40 after 1961

“…Green monkeys are usually free of SV40 but are susceptible to SV40 infection. Of note, SV40 strain VA-45-54 (one of the strains we detected in this study) was derived from primary African green monkey cells (17). The other strain that we detected, CPC-MEN, was originally isolated in 1984 from a human brain tumor in a German patient (18).…”

A Serological Survey of Simian Virus 40 in Monkeys

“…The discovery that SV 40 is oncogenic for certain newborn laboratory animals (3,10) has raised the question of its carcinogenicity in man (2 , 5, 7, 15), particularly since this agent has been found in the live attenuated (Sabin) poliovirus vaccine of monkey cell culture (17). Thus, the use of monkey kidney cell cultures for viral vaccine production or research purposes has been a critical problem.…”

Simian Virus 40 Infection of Humans

“…Although poliovirus in the Salk vaccine was inactivated by formalin treatment, the conditions were insufficient to completely inactivate SV40. Soon thereafter, it was demonstrated that SV40 could infect humans and also induce tumors in experimental animals (26,28,29,42,43). These observations raised concerns that vaccinated people worldwide may have been inadvertently exposed to an oncogenic virus.…”

“…During the initial phase of the infection, generally the first 4 weeks, approximately 0.1% of the cells produce 500 to 1,000 virions per cell. Virus output from the culture then remains at a constant, very low level but with 100% of the cells producing virus at a rate of approximately 1 to 2 virions/cell (41,42,108). Once the cell culture progresses through crisis, virus production generally decreases, accompanied by a concomitant decrease in production of viral capsid proteins and an increase in the production of LT. One interpretation of these data is that the cells producing large amounts of virus are killed, but the cells that produce low levels of virus (as assayed by infectious center assays) survive.…”