Development of a new sero-diagnostic test for the specific detection of Dengue and Zika Flavivirus infections.

Dengue, yellow fever and Zika viruses belong to the flavivirus family. They co-circulate and are transmitted by the same mosquito. To adapt the medical care of patients with flavivirosis, it is necessary to be able to quickly identify the infecting virus. The most discriminating test is currently based on viral genome detection but it is mostly successful within five days of infection, after which the virus is no longer present in the blood. Sero-diagnosis is currently also carried out, aimed at detecting immunoglobulin M (IgM) before the appearance of IgG. However, antibodies directed against different flavivirus antigens can present cross-reactivities due to the homology of their genome sequences and structures. Thus, a positive sero-diagnosis indicating a recent infection by a flavivirus is usually not very discriminating. Therefore, the development of a more sensitive and specific test for early detection of flavivirus infection is warranted. This test could be implemented in specialized laboratories, in national reference centers, or even at the patient's bedside as a rapid diagnostic test (RDT). The project aims to design diagnostic tools to detect IgM directed against the most common arboviruses with very good sensitivity and specificity. We are currently developing an antigen presentation platform based on a bacteriophage capsid. This platform will be combined to viral antigens that do not favour cross-reactions and a reporter protein for detection, thereby alleviating the need for inactivated whole flavivirus that are currently used at national reference centers for arboviruses. The developed diagnostic tool will be tested to study cohorts of patients living in or having travelled to an endemic area, in order to carry out retrospective epidemiological studies.