- Lymphocytic 2',5'-oligoadenylate synthetase activity increases prior to the appearance of neutralizing antibodies and immunoglobulin M and immunoglobulin G antibodies after primary and secondary immunization with yellow fever vaccine. Bonnevie-Nielsen, V., Heron, I., Monath, T.P., Calisher, C.H. Clin. Diagn. Lab. Immunol. (1995)