A review.There are a number of specific characteristics to be considered when developing and manufacturing vaccines.This article discusses specific requirements to be fulfilled for three attenuated live bacterial vaccines (LBVs) including Mycobacterium bovis BCG vaccine against tuberculosis, Salmonella typhi Ty21a vaccine against typhoid fever, and Vibrio cholerae CVD 103-HgR vaccine against cholera.Special characteristics for these vaccines comprise the appropriate level of attenuation, the balance between safety and immunogenicity, the genetic stability of the organisms combined with environmental risk assessment, the challenge of old-fashioned upstream and downstream methods in combination with quality control of the final product, and the release requirements.