Elucidation of the mechanisms of pathogenesis underlying the diseases
caused by viruses and bacteria has fascinated scientists for many years
in two ways. Firstly, these pathogenic agents represent relatively sim-
ple biological systems for the study of basic biological processes such
as replication, gene regulation, genetic variability and host-pathogen
interactions. Secondly, process in this field is valuable in a practi-
cal sence, since it can help in the control of these diseases. The
avail- ability of new genetic and immunological techniques, especially
recom- binant DNA methods and monoclonal antibody technology, has
provided powerful tools for unravelling the genetic, biochemical and
immunologi- cal basis of viral and microbial pathogenesis. Molecular
cloning has allowed the isolation of single genes or groups of genes
related to phenotypes which appear to be immunologically important for
pathogene- sis. The specific elimination of such genes from the complex
genomes of the pathogens can now be achieved with similar genetic
techniques. These genetic studies have provided additional information
on the role played by specific phenotypic traits in pathogenesis,
especially when combined with relevant animal model systems.
Furthermore, the struc- tural analysis of important virulence factors
and surface antigens may allow the prediction of antigenic domains
suitable for the development of new vaccines. The 38th Mosbacher
Colloquium focuses on the molecular basis of viral and microbial
pathogenesis. The virology part begins with the well- studied plant
viroids. The unusual structure of their genome, as well as knowledge
about their replication and pathogenicity, are presented.