DIFFERENCES IN THE IMMUNOGENICITY OF NATIVE AND FORMALINIZED CROSS-REACTING MATERIAL (CRM197) OF DIPHTHERIA-TOXIN IN MICE AND GUINEA-PIGS AND THEIR IMPLICATIONS ON THE DEVELOPMENT AND CONTROL OF DIPHTHERIA VACCINE BASED ON CRMS

Immunogenicity of native and formalized cross reacting material (CRM19 7) of diphtheria toxin (DTx) was assessed in mice and guinea pigs. For the primary response, mice produced similar levels of diphtheria toxo id (DTxd) IgG antibodies to both native and formalinized preparations of CRM197 though the antibody levels were significantly lower than tho se elicited by conventional DTxd (P < 0.05). In contrast, guinea pigs showed significantly higher levels of DTxd IgG antibodies to the forma linized CRM197 preparation than the native preparation (P < 0.001) aft er single injection. These differences in the immunogenicity of mice a nd guinea pigs to native and formalinized CRM197 preparations have imp lications for the development and control of diphtheria or other vacci nes involving the use of CRMs. (C) 1997 Elsevier Science Ltd.