Immunogen sequence: ETSLAECTFT KRRTMGYQDF ADVVCYTQKA DSPMDDFFQC VNGKYISQMK ACDGINDCGD QSDELCCKAC QGKGFHCKSG VCIPSQYQCN GEVDCITGED EVGCAGFASV AQEETEILTA DMDAERRRIK SLLPKLSC. Factor I, a serine protease, is a regulatory component of both the alternative an