New S19 Mutant to Improve Distinction Between Infected and Vaccinated Animals.

Background: Using Strain 19 (S19) to control bovine brucellosis is restricted due to induce antibodies to the O-side chain of the smooth lipopolysaccharide (LPS) which may be difficult to differentiate vaccinated and infected animals. Furthermore, it is virulent for humans and can induce abortion to cattle.

Objectives: The aim of this study was to employ gene knockout S19 for the first time to eliminate diagnostic defects and obtain the attenuated mutant strain.