Characterization of Nairovirus replication in Hyalomma-derived tick cell lines

Background: Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic viral disease that is asymptomatic in infected animals, but a serious threat to humans. Human infections begin with nonspecific febrile symptoms that progress to a serious hemorrhagic syndrome with a high case fatality rate. CCHF virus (CCHFV) is classified as a biosafety level 4 pathogen and is the second most widespread medically important arbovirus after dengue virus. CCHFV has been found in at least 31 species of ticks; in particular, members of the genus Hyalomma seem to be the principal vectors as they play an important role as a natural reservoir. Methods: The susceptibility of two Hyalomma anatolicum-derived cell lines to infection with CCHFV and Hazara virus (HAZV), an apathogenic virus closely related to CCHFV, was investigated by classical and molecular techniques in order to compare CCHFV and HAZV virus/host interactions in the context of arthropod cells. Results and conclusion: Our results showed that CCHFV and HAZV chronically infected tick cells without any cytopathic effect. Infected cells released viral particles to supernatant for at least 200 days post infection. Although both cell lines have the same susceptibility to CCHFV and HAZV, in the case of HAZV infection we observed strong differences in the kinetics of viral progeny release in the early stages. Currently, a transcriptomics approach is being used to study the cellular response to nairovirus infection.