In recent years our horizons regarding the role of nucleic acids in biological systems have been expanded vastly by the finding that these molecules not only carry and transmit specific infOImation but also can act as less specific triggers of antiviral factors and of immunological responses. The latter properties are of particular interest in terms of possible utilization in human and veterinary medicine and consequently led, in the last few years, to the development of a new research area that combines both fundamental and applied problems in a uniquely attractive way. Furthermore, the...