Molecular characterization of tick-virus interactions

All viruses infecting ticks (with one possible exception) are arboviruses; their survival depends on infection and replication in both tick and vertebrate host cells. Little is known of arbovirus-tick molecular interactions even though tick-borne viruses spend most of their existence in ticks. Initial interactions occur in the midgut, where bloodmeal digestion is intracellular in contrast to hematophagous insects. The contrast may explain differences in surface architecture of tick-borne and insect-borne orbiviruses. Other indications of molecular interactions can be extrapolated from vertebrate cells, such as utilization of aggresome pathways. Although many tickborne viruses exploit the immunomodulatory effects of tick saliva, there is no evidence they interact directly with saliva molecules. However, the most fundamental unanswered question concerns the benign infection of arboviruses in tick cells compared with their cytopathic effect in vertebrate cells. As the tick proteome is unraveled, its interaction with the viral proteome should shed new light on the molecular interface between ticks and the many important viruses they transmit.