Monoclonal (mAb) selection schematic. Mice were immunized with whole gametes/zygotes, gamete/zygote membranes, or material immunoprecipitated with Pfs230-specific mAb 1B3 or Pfs25-specific mAb 4B7. The latter two immunogens induced more potent transmission-reducing activity (TRA) and splenocytes from 3 mice in each of these groups were used to generate hybridomas. The IgG+ hybridoma supernatants were screened for gamete/zygote surface reactivity using flow cytometry and the surface reactive IgGs were tested for TRA using a standard membrane feed assay. All the TRA and selected nonTRA hybridomas were cloned and rescreened for gamete/zygote surface reactivity, TRA and antigen reactivity. Antigen reactivity was assessed by immunoblot, surface reactivity with gametes/zygotes that do not express Pfs230 (Pfs230 minus IFA), and mass spectroscopy (MS/MS).