Assessment of thermal influence on the interaction dynamics between nairovirus and vectors: implications for viral transmission and ecology

Crimean-Congo haemorrhagic fever (CCHF) is a severe widespread tick-borne disease with a case fatality rate up to 40%, caused by the CCHF virus (CCHFV). Due to its high pathogenicity and the lack of specific treatment, CCHFV is classified as a biosafety level 4 pathogen, and can therefore be handled only in high-containment facilities. For this reason, the closely related Hazara virus (HAZV) is used as a surrogate model for CCHFV, as it can be manipulated in biosafety level 2 laboratories (it is not pathogenic in humans). The geographical distribution of CCHFV is strongly associated with the distribution of ticks of the genus Hyalomma, which act as both vectors and reservoirs for the virus. In recent years, several factors, including climate change, have contributed to the expansion of Hyalomma ticks into previously unaffected areas, raising concerns about the potential emergence of CCHF in these novel invaded regions. This thesis investigates how virus-host interaction is influenced by temperature, with a particular focus on cellular viability and viral replication efficiency. Moreover, it explores whether HAZV and tick cell lines can adapt to different thermal conditions, providing insight into the potential for arboviruses such as CCHFV to adapt to ongoing and future environmental changes.