Immunogen sequence: PDVPNAQPAL EGRTSFPEDT VITYKCEESF VKIPGEKDSV ICLKGSQWSD IEEFCNRSCE VPTRLNSASL KQPYITQNYF PVGTVVEYEC RPGYRREPSL SPKLTCLQNL KWSTAVEFCK KKSCPNPGEI RNGQIDVPGG ILFGATISF. CD55 (decay-accelerating factor, DAF) is a GPI-anchored membrane glyc