A specific radioimmunoassay for vitellogenesis in mosquitoes

Hagedorn's assay for vitellogenesis, in which a crude antigen-antibody complex is collected directly on a Millipore membrane, without prior separation of soluble from insoluble proteins, is unspecific. This was proven as follows.Fat bodies of blood-fed mosquitoes (Aedes aegypti) were incubated in a medium containing ³H valine. The medium was analyzed for synthesis of vitellogenin by incubation with serum of normal rabbits (control) or of rabbits which were immunized against mosquito egg protein (antibody).When these mixtures were filtered directly through Millipore membranes (Hagedorn's method), the radioactivity in the control was about two-thirds of that in the antibody membrane. However, when the antigen-serum and antigen-antibody complex were centrifuged, the antigen-serum precipitate (control) contained only a very small percentage of the radioactivity present in the antigen-antibody precipitate. Apparently, the medium contained a large amount of soluble, nonvitellogenic protein that binds to the membrane.Analysis of the fat body homogenate showed that a large amount of the newly synthesized vitellogenin was stored intracellularly.Since all published data on vitellogenesis in mosquitoes depend on Hagedorn's assay, the validity of current concepts of the control of vitellogenesis in mosquitoes is open to question.