Immunogen sequence: LAPRRCPAQE VARGVLTSLP GDSVTLTCPG VEPEDNATVH WVLRKPAAGS HPSRWAGMGR RLLLRSVQLH DSGNYSCYRA GRPAGTVHLL VDVPPEEPQL SCFRKSPLSN VVCEWGPRST PSLTTKAVLL VRKFQNSPAE DFQEPCQYSQ ESQKFSCQLA VPEGDSSFYI VSMCVASSVG SKFSKTQTFQ GCGILQPDPP ANITVTAVAR NPR