Open AccessAntibody response in mice immunized with a plasmid DNA encoding the colonization factor antigen I of enterotoxigenic Escherichia coli
Author(s) -
Alves Ada M.B,
Lásaro Marcio O,
Pyrrho Alexandre S,
Gattass Cerli R,
Almeida Darcy F,
Ferreira Luís C.S
Publication year - 1999
Publication title -
fems immunology & medical microbiology
Language(s) - English
Resource type - Journals
eISSN - 1574-695X
pISSN - 0928-8244
DOI - 10.1111/j.1574-695x.1999.tb01254.x
Subject(s) - enterotoxigenic escherichia coli , biology , antibody , antigen , recombinant dna , bacterial adhesin , microbiology and biotechnology , immunoglobulin g , isotype , immunoglobulin a , dna vaccination , escherichia coli , virology , immunogenicity , immunization , enterotoxin , immunology , gene , monoclonal antibody , biochemistry
The colonization factor antigen I (CFA/I) is one of the most epidemiologically relevant enterotoxigenic Escherichia coli (ETEC) fimbrial adhesins, which mediates the binding to human small intestine epithelium. A recombinant eukaryotic expression plasmid, pRECFA, encoding the CFA/I protein fused to the glycoprotein D of herpes simplex type 1 virus, was used to generate an antibody response in a murine model following intramuscular inoculation of purified DNA. Eukaryotic cells (BHK‐21) transfected with pRECFA expressed the CFA/I protein in vitro, as revealed by Western blot and immunofluorescence microscopy. Administration of a single pRECFA 100‐μg dose induced a long‐term CFA/I‐specific antibody response in BALB/c mice composed mainly of IgG and, to a lesser extent, IgA isotypes. The major CFA/I‐specific IgG subclass was IgG2a, suggesting a Th‐1‐type immune response. A second dose with the same amount of purified DNA, given 2 weeks later, caused a booster effect on the immunoglobulin levels, but did not qualitatively alter the isotypes and subclasses of the induced antibody response. Immunization with different amounts of purified DNA and/or number of doses showed that maximal transient CFA/I‐specific antibody levels could be obtained after two 100‐μg doses of pRECFA given 2 weeks apart, but long‐term antibody levels were similar.