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Avian Leukosis Antibody Response in Individuals Given Chicken Embryo Derived Vaccines

Under natural conditions, avian leukosis viruses (ALV) produce in chickens a variety of malignant disorders, manifested as solid invasive tumors, lymphomatosis, myeloblastosis, etc. As these agents are ubiquitous in conventional chicken flocks and are transmitted vertically from hen to egg, virtually all vaccines derived from conventional eggs are contaminated with ALV (1—4). Experimentally, some strains of Rous sarcoma virus (RSV) have produced tumors in nonavian species (5), including nonhuman primates (6). Because of this, the question of the potential oncogenicity of ALV to humans arises. There have been isolated reports of serologic surveys of ALV antibody in man (2, 3). These previous studies were limited to the detection of neutralizing antibody to the Bryan strain of RSV, a test only sensitive to subgroup A avian leukosis viruses. We have, therefore, examined multiple sera from individuals inoculated with ALV-contaminated vaccines for the presence of antibody by employing the broadly reacting COFAL (7) and the highly sensitive indirect immunofluorescence (FAB) tests. The COFAL test is able to detect antibody to ALV of any subgroup. In the FAB test, subgroup A, B, and C antigens were employed to broaden the antigenic spectrum to cover the three largest ALV subgroups. Neutralization tests were performed on some sera. The results of these studies constitute this report. Materials and Methods. Vaccines. All ALV-contaminated vaccines were produced in chicken embryos derived from conventional flocks and were known to be contaminated with ALV. The ALV-free yellow fever vaccine (YFV) was prepared in ALV-free eggs from seed lots also free from ALV (4). Sera. Pre- and postimmunization serum samples were obtained from the following individuals inoculated with ALV-contaminated vaccines: 35 volunteers who received formalin-inactivated influenza vaccine in single or multiple doses; 15 inoculated with formalin-inactivated epidemic typhus vaccine; 15 who were given live attenuated measles vaccine; 15 who received conventional 17D YFV; and 15 who were given live smallpox vaccine.