Cross antigenicities of Leptospira interrogans serovar copenhageni Shibaura strain for preparing biological products in Japan.

Cross protective antigenicities of Leptospira were studied with 16 antisera to 13 serovars of Leptospira interrogans and a virulent strains "Shibaura (V)", which is now considered to belong to serovar copenhageni, for challenge. The antisera of the rabbits highly immunized with various serovar live antigens were examined for leptospiricidal activity; cross immunity was recognized only in the same serogroup, Icterohaemorrhagiae. Serovar icterohaemorrhagiae lacks a prt of the antigenic components of copenhageni, but the antiserum to the former showed potent leptospiricidal activity to Shibaura (V). Anti-copenhageni immune serum absorbed with the icterohaemorrhagiae antigen did not show any protective activity to Shibaura (V).