BCG vaccine bacilli that seemed less virulent, and changed the course of their research to see if repeated subculturing would produce a strain that was attenuated enough to be considered for use as a vaccine. The BCG strain was isolated after subculturing 239 times during 13 years from virulent strain on glycerine potato medium. The research continued throughout World War I until 1919, when the now avirulent bacilli were unable to cause tuberculosis disease in research animals. Calmette and Guerin transferred to the Paris Pasteur Institute in 1919. The BCG vaccine was first used in humans in 1921. Public acceptance was slow,
Inoculation loop Inoculation loop An inoculation loop, also called a smear loop, inoculation wand or microstreaker, is a simple tool used mainly by microbiologists to retrieve an inoculum from a culture of microorganisms. The loop is used in the cultivation of microbes on plates by transferring inoculum for streaking. It can also be used to transfer microscopic organisms. Touching a broth or a culture plate will gather enough microbes for inoculation. The wire forms a small loop with a diameter of about 5 mm. The loop of wire at the tip may be made of platinum, tungsten or nichrome, the latter being