IMMUNOGLOBULIN-G SUBCLASS RESPONSES IN MICE IMMUNIZED WITH PLASMID DNA ENCODING THE CFA I FIMBRIA OF ENTEROTOXIGENIC ESCHERICHIA-COLI/

Balb/c mice immunized either with a plasmid vector (pRECFA), encoding the CFA/I fimbrial adhesin of enterotoxigenic Escherichia coli (ETEC), or purified CFA/I fimbriae induced similar antibody responses in rega rd to the kinetics of serum total immunoglobulins and IgG. Nonetheless , the IgG subclass responses in mice vaccinated with DNA were composed predominantly by IgG2a (ranging from 39 to 74% of the total anti-CFA/ I IgG) and, to a lesser extent, by IgG1 (ranging from 15 to 24% of the total anti-CFA/I IgG) during a 12 week observation period. On the oth er hand, mice immunized with purified CFA/I presented mainly an IgG1 a ntibody response (ranging from 39 to 67% of the total anti-CFA/I IgG). These results indicated that, irrespective of the immunogenic propert ies and-or origin of the encoded antigen, immunization with pRECFA eli cited an specific IgG subclass response which may affect the ability o f DNA vaccines to induce a protective immune response against CFA/I me diated colonization of ETEC bacterial cells. (C) 1998 Elsevier Science B.V. All rights reserved.