Establishment of the non-virulent strain of Bacillus anthracis

The aim of the present study is to search for a new non-virulent strain of Sacillus anthracis used for the vaccine preparation and for immunological assay,the attenuated strain of B.anthracis used in the predaration of anthrax vaccine was futher attenuated by the traditional high temperature attenuation method.The avirulent strain for vaccine preparation was cultured on plates of beef digestive agar for 48 hours and passed for 40 consecutive days.A new nonvirulent strain of B.anthracis (AAT121) was obtained,and it was proved to be avirulent after complete examination of its biological characteristcs.It has lost the plasmid pXO1 that was present in the parent strain A16R,and also lost the power to produce toxins and almost lost the ability to from spores.Thus,it had been become a real non-virulent strain of B.anthracis.No other biological and biochemical alteration was found.It concludes that a new avirulent stain of B.anthracis can be further attenuated by method of high temperature attenuation and can be applied for the related studies.