ABSTRACT
For many years my major interest has been the study of tick-pathogen interactions. In 1955 I decided to cultivate tick cultures in vitro. The major reason was that ticks are second only to mosquitoes as the most important vectors of human and animal-pathogenic viruses, rickettsiae, spirochetes, and protozoan parasites. Tick organs, tissues, and cells in vitro could bring new dimensions to the study of tick-borne pathogens and of their interactions with tick vectors. In vitro studies could elucidate parasite life cycles in arthropod hosts and help design strategies for eventual control. Furthermore, tick cultures in vitro could be used to recover tick-borne agents from nature, otherwise difficult or impossible to isolate and propagate in vertebrates in vivo and in vitro, since ticks, the natural hosts, would be the most susceptible substrates. Close relationships between pathogens and their tick hosts suggest the absence of cytopathic effects in the hosts and retention of full virulence for mammalian hosts. The latter characteristic is very important for the preparation of appropriate antigens and highly effective vaccines.
