Attenuated bacteria with altered DNA adenine methylase activity

摘要: The present invention is directed towards an attenuated Strain of pathogenic bacteria (eg Haemophilus, E. Coli, and/or Salmonella) having non-reverting genetic mutations relative to the wild-type organism which alter activity of DNA adenine methylase (Dam). The invention further includes compositions comprised of the attenuated bacteria and methods using these compositions to elicit an immune response to produce highly Specific antibodies. The inven tion also provides methods for preparing vaccines as well as Screening methods to identify agents which may have anti bacterial activity.