Attempts to Interrupt Virus Tumorigenesis by Immunization Using Homologous “Bjorklund-Type” Antigen. ∗

Summary

Studies were carried out to determine whether “Bjorklund-type” lipoprotein tumor antigen could interrupt the appearance of tumors in animals infected at birth with oncogenic viruses. The polyoma and SV₄₀ hamster systems were employed. “Bjorklund-type” antigen was prepared from corresponding virus-induced tumor and was made into aqueous and mineral oil adjuvant formulations. These vaccines were given during the time period between virus inoculation and first appearance of tumors. Also, adult animals, not previously exposed to virus, were immunized prior to challenge with homologous tumor transplant. None of the adult hamsters given “Bjorklund-type” antigens developed detectable cytolytic or precipitating antibody against homologous tumor. The vaccine was antigenic, however, as proved by development of such antibody in the heterologous guinea pig and rabbit species. The experiments were designed to determine whether protection would be afforded by the vaccine and such was clearly not obtained. Instead, a small but statistically significant enhancement of tumor induction was noted. The implications of these findings are discussed and a word of caution is given, on theoretical bases, for studies of such vaccines in man.