Tumor Immunity in Hamsters Infected with Adenovirus Type 12 or Simian Vims 40

Abstract

Summary The oncogenicity of adenovirus type 12 and SV₄₀ administered to hamsters when newborn could be inhibited or prevented by administration of large doses of the homologous virus at later dates. The protection achieved appeared to vary inversely with the concentration of virus in the initial infecting dose. The administration of greater initial infecting doses of virus resulted in fewer tumor-free animals in the treated groups. The size of the dose of virus used in treatment was a factor, and a large dose (1 ml) gave a little more protection than a 0.25 or 0.5 ml dose. The usual course of treatment was a total of 13 doses of virus administered at twice weekly intervals. Smaller numbers of doses used in treatment were sometimes effective. Treatment with virus heated to 50°C for an hour in the presence of magnesium chloride was not effective in preventing the induction of tumors.