Hypersensitivity to influenza virus preparations, vaccines, and egg proteins measured in rabbit pyrogen test

Summary

Sensitization of rabbits to the influenza virus and egg protein preparations was achieved by intravenous and intramuscular injections. 10–12 days later the previously sensitized animals were challenged with homologous or heterologous antigen intravenously. Sensitized animals developed a disturbed temperature regulation being expressed by hypo- and/or hyperthermia. Signs of shock rarely occurred. The febrile response was usually monophasic and regularly accompanied by initial hypothermia. Significant hypo- and hyperthermia were obtained in animals sensitized and challenged with crude normal and influenza virus infected allantoic fluids. An unexpected fever response was obtained using purified egg white lysozyme. Purified influenza virus preparations and two commercial influenza virus vaccines led to different results. Around 50 per cent of the animals injected with these materials remained unresponsive. The residual rabbits developed either hypothermia only or a slight hyperthermic reaction. Apparently foreign protein antigens could be eliminated just completely. The results support the supposition that fever may result from specific protein antigen challenge in animals manifesting hypersensitivity. The technique of rabbit pyrogen test using sensitized animals appears to be useful to detect undesirable egg proteins in influenza virus vaccines and should be employed and possibly standardized.