The immunostimulatory prospects of bacterial DNA have attracted the interest and attention of scientists and physicians and become a major focus in immunobiology and biomedicine. These activities are the product of immunostimulatory DNA sequences (ISS, also known as GpG motifs), which are rare in the mammalian genome. ISS were shown to enhance immunological responses and were used to confer protection to a wide variety of tumors, allergic inflammation, and infections. In Microbial DNA and Host Immunity, leading researchers review the activation of the mammalian immune system by bacterial DNA and consider the applications of ISS in clinical medicine. The authors survey the latest findings concerning the receptor-recognition and signaling pathways triggered by ISS, the process of cell activation, and potential vaccination strategies using ISS. Specific pharmaceutical applications discussed include infectious disease (Hepatitis B, HIV, and mycobacterial infections), allergy (asthma and conjunctivitis), cancer (lymphoma), and inflammation and autoimmunity (arthritis and colitis). Up-to-date and informative, Microbial DNA and Host Immunity illuminates the immunobiology of bacterial DNA and its promise of powerful new vaccines to provide protective immunity against infections, tumors, and chronic disease.