Characterization of Adaptive Immune Responses to Oropouche Virus (OROV) Infection

Oropouche virus (OROV), a re-emerging South American arbovirus causing dengue-like fever and occasional neurological complications, is expanding its circulation towards more densely populated areas in French Guiana, as evidenced by recent cases near Cayenne in 2026. While animal models indicate that B cell-mediated humoral immunity is critical for viral control, the human antibody response to OROV remains poorly characterized. Despite WHO-led international research efforts, there is currently no vaccine, antiviral treatment, or described human monoclonal antibody against OROV - a major gap that hinders therapeutic and vaccine development. Identifying human neutralizing monoclonal antibodies could offer a promising therapeutic option, particularly for vulnerable populations such as pregnant women.

Inclusion Criteria: For all: * Adults (≥18 years old) * Willingness to participate in the study after explanation and signing of the informed consent form Study population 1: \- Presenting a laboratory-confirmed OROV infection, defined by a positive real-time RT-PCR and/or positive seroneutralization performed as part of the management of and response to the 2020 OROV epidemic in Saül. Study population 2: \- Residing in Trois-Sauts for at least 5 years Study population 3: \- Presenting a laboratory-confirmed OROV infection, defined by a positive real-time RT-PCR and/or positive seroneutralization, identified in the Cayenne area and surrounding localities during the study period, as part of the surveillance activities of the CNR for Arboviruses (IPG). Exclusion Criteria: For all: * Pregnant women. * Individuals presenting with severe chronic pathologies (notably active cancer, primary or secondary immunodeficiency, immunosuppressive treatment, HIV infection, or autoimmune diseases), according to the information declared by the participants.