Protein-based tools for the detection and characterisation of Oropouche virus infection

Oropouche fever is a neglected tropical viral disease endemic to Latin America and the Caribbean. Oropouche fever is caused by Oropouche virus (OROV), an orthobunyavirus with a tri-segmented (-)ssRNA genome. A recent epidemic caused by a novel reassortant has seen the first recorded deaths from OROV infection and reports of vertical transmission, affecting individuals across a dramatically expanded geographical range. Despite its importance as an emerging pathogen, research into OROV infection is hampered by paucity of available tools for serology and molecular virology. We have purified high-quality recombinant OROV nucleoprotein and the spike region of the viral surface glycoprotein Gc. We have used these antigens in indirect ELISA to detect seroconversion following experimental infection of animals, confirming their antigenic authenticity. These antigens stimulate the production of high neutralizing antibody titres in animals, highlighting their promise as immunogens for vaccination. We generated nanobodies that recognize both recombinant and infection-derived OROV antigens and developed a sandwich ELISA assay that can detect OROV antigens in human clinical serum samples with high efficiency. We have also shown that recombinant nanobodies directed against OROV Gc spike can potently neutralise infection by both historical OROV strains and the newly emerged reassortant. These protein-based reagents will accelerate OROV research and highlight the utility of protein-based tools for future OROV vaccines and point-of-care diagnostic devices.