| 摘要 |
<p>The present invention provides a mutant C. fetus strain in which each of the cassettes is replaced by a heterologous antigen. Also provided is a mutant C. fetus strain in which all but one of the cassettes are replaced by a heterologous antigen. Further provided is a mutant C. fetus strain in which recA is mutagenized and a C. fetus strain in which recA is mutagenized and the expressed sapA homolog is a chimera involving a heterologous peptide.</p> |
