Biological Activity of Papain Digested Streptococcal Anti-M Antibody

Digestion of rabbit streptococcal anti-M antibody with papain to produce univalent fragments resulted in the loss of its ability to fix complement. However, the digested univalent antibody still retained the indirect bactericidal activity in vitro, opsonic activity in vivo, and also the capability of protecting mice against the streptococcal infection. Thusly the biological activities of digested anti-M antibody appear to be similar to those of intact anti-M antibody.