Antibody response in mice immunized with a plasmid DNA encoding the colonization factor antigen I of enterotoxigenic Escherichia coli.
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-microg 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-microg doses of pRECFA given 2 weeks apart, but long-term antibody levels were similar.
Alves
A M
AM
Instituto de Biofísica Carlos Chagas Filho, Cidade Universitária, Rio de Janeiro, RJ, Brazil. adaalves@biof.ufrj.br
Lásaro
M O
MO
Pyrrho
A S
AS
Gattass
C R
CR
de Almeida
D F
DF
Ferreira
L C
LC
D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology; D002460:Cell Line; D006224:Cricetinae; D004269:DNA, Bacterial / Q000276:immunology*; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology*; D036781:Fimbriae Proteins; D007132:Immunoglobulin Isotypes; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010452:Peptide Biosynthesis; D010957:Plasmids / Q000276:immunology*; D014611:Vaccination / Q000379:methods; D019444:Vaccines, DNA / Q000276:immunology
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D004269:DNA, Bacterial; D007132:Immunoglobulin Isotypes; D019444:Vaccines, DNA; C022924:colonization factor antigens; D036781:Fimbriae Proteins