P2Y12–P-Selectin Mediated Platelet Activation Drives Dengue-Associated Thrombocytopenia

Dengue virus (DENV) infection frequently causes thrombocytopenia, a hallmark of severe disease. The underlying mechanisms of this condition remain incompletely understood. Using a murine model that mirrors human hematologic and inflammatory responses, we show that DENV impairs megakaryopoiesis, causing necrotic loss of bone marrow megakaryocytes and compensatory thrombopoietin elevation. Megakaryocyte-derived platelets exhibit mitochondrial dysfunction and phosphatidylserine exposure, consistent with apoptosis. Systemically, DENV drives P-selectin– dependent platelet activation and platelet–monocyte aggregates, accompanied by increased plasmatic chemokines (CXCL4, CCL5, CXCL1) and vascular leakage in target organs such as liver and lungs, reflecting heightened thromboinflammation. Pharmacologic blockade of P-selectin or inhibition of P2Y12 with clopidogrel restored platelet counts, rescued megakaryocyte numbers, and reduced systemic inflammation. Collectively, these findings demonstrate for the first time in an in vivo model that DENV-induced thrombocytopenia arises from combined megakaryocyte impairment and platelet hyperactivation and highlight platelet-targeted interventions as potential therapeutic strategies.