Using the Gut Antigen HA86 as a Biomarker for Hyalomma Tick Bites, the Principal Vectors of the Crimean-Congo Hemorrhagic Fever Virus

Abstract

Hyalomma ticks are the principal vectors of the Crimean-Congo hemorrhagic fever virus. Antibody responses and the viral genome, are usually used for virus surveys. These markers cannot assess the role of ticks in the burden of CCHFV. It has been documented that tick bites induce a host immunological response, and numerous antigens have been described. To note, the gut protein Bm86 of Boophilus micropulus induces such an immune response, and several orthologues have been identified. Furthermore, a cross-immunological response against orthologues was reported. Based on these findings, we hypothesized that the Bm86 of Hyalomma ticks could serve as a biomarker of exposure to Hyalomma tick bites. For this purpose, 2432 ticks, 435 human and 480 animal sera, collected in Agnam (Northern Senegal) between February 2021 and April 2022 for arbovirus and viral hemorrhagic fever surveys were used. We found that the development of HA86 IgG in livestock sheep is influenced by exposure to Hyalomma ticks. Additionally, the anti-HA86 antibodies did not persist for more than 2 months, and no cross-HA86 response wasn’t detected between Hyalomma and Rhipicephalus species. These results suggest that HA86, could be used as a biomarker for Hyalomma tick bites.