Construction and characterization of a brucella suis S2 strain with a chloramphenicol resistance marker
带有氯霉素抗性基因标记的重组布氏杆菌S2的构建及其生物学特性

Vaccination has not been used widely because of the interference in the discrimination between infected and vaccinated animals in immune-screening procedures. In the present study,chloramphenicol resistance gene(Cm~r)was cloned into the genomic DNA of brucella suis S2 strain by homologous recombination with knocking out the WbkC gene,and obtained the recombinant rS2-WbkC. Further study confirmed that rS2-WbkC was conversed into rough-phenotype form smooth-phenotype. The recombinant keeps the ability to chloramphenicol resistance after 25 passages in tryptic soy agar (TSA). Mice tests showed rS2-WbkC offered similar protection to S2 strain,but more safe than S2. Serum collected form rS2-WbkC immunized mice could be easily distinguished from antiserum produced by smooth-phenotype brucella abortus. In view of these result,rS2-WbkC is a promising candidate for vaccine strain.