Platelet indices: Is it a reliable biomarker in viral infections?

Platelets are non-nucleated blood cells that are essential for maintaining hemostasis. While platelet activation and increased platelet numbers (thrombocytosis) are associated with a higher risk of thrombotic events, low platelet counts (thrombocytopenia) and a variety of platelet function abnormalities are associated with a higher risk of bleeding. Platelets and their activation state have been proven in recent years to influence innate and adaptive immune responses, and low platelet counts have been identified as a surrogate indicator for poor prognosis in septic patients. Platelet activation frequently occurs in conjunction with viral infections. Viruses, on the other hand, can interact directly with platelets and megakaryocytes, modulating their function. All these factors contribute to platelet activation, which leads to increased platelet consumption and elimination, as well as thrombocytopenia, which is common during viral infection Platelets and their secreted products have been demonstrated to suppress infection and aid virus persistence in the presence of certain viruses, making platelets a double-edged sword during viral infections. In this review we have highlighted about what is currently known about platelet interactions with various types of viruses, virus effects on platelet activation, as well as platelet-mediated regulation of innate and adaptive immune responses.