Tick-borne viruses.

Tick-borne viruses (TBVs) belong to the largest biological group known as arboviruses with unique mode of transmission by blood-feeding arthropods (ticks, mosquitoes, sand flies, biting midges, etc.) to a susceptible vertebrate host. Taxonomically, it is a heterogenous group of vertebrate viruses found in several viral families. With only one exception, African swine fever virus, all TBVs have a RNA genome. To date, at least 160 tick-borne viruses are known, some of them pose a significant threat to human and animal health worldwide. Recently, a number of established TBVs has re-emerged and spread to new geographic locations due to the influence of anthropogenic activities and few available vaccines. Moreover, new emerging tick-borne diseases are constantly being reported. Major advances in molecular biotechnologies have led to discoveries of new TBVs and further genetic characterization of unclassified viruses resulting in changes in TBVs classification created by the International Committee for the Taxonomy of Viruses. Although TBVs spend over 95% of their life cycle within tick vectors and the role of ticks as vectors has been known for over 100 years, our knowledge about TBVs and molecular processes involved in the virus-tick interactions is scarce.

Immunomodulators in tick saliva and their benefits.

Ticks are significant bloodsucking ectoparasites. Apart from causing blood loss and host skin damage, ticks are important vectors of tick-borne pathogens that cause disease in humans and animals as well as significant economic loss. For biological success, ticks evolved these substances with immunomodulatory activities capable of inhibiting host defence reactions (haemostasis, inflammation and immunity reactions), and which have a radical significance for their survival. The resulting feeding site represents a favourable environment and many pathogens began exploiting ticks to facilitate their transmission to the host. The structural-functional relationships of some salivary compounds have been outlined; however research on tick sialomas indicates that further extensive exploration is required on the subject. Also, tick saliva is a complex pharmacological component with great therapeutic potential for the treatment for some diseases.