Open Collections

Tegegn, Tseday Zewdu

University of British Columbia

According to the World Health Organization, approximately 50% of the world’s population lives in regions where dengue virus (DENV) is endemic. Each year, about 400 million people are infected, of which nearly half remain asymptomatic despite high virus titers. Symptomatic cases can lead to severe hemorrhage and vascular leakage, resulting in over 25,000 deaths annually. Thrombocytopenia, characterized by a reduction in platelets (PLTs), which are critical for clot formation and immune surveillance, is common in all severities of DENV infection and often contributes to organ failure and mortality. Previous studies have identified several mechanisms for DENV-induced PLT dysfunction and thrombocytopenia, including suppression of PLT production in the bone marrow and peripheral destruction of PLTs. Yet, our understanding remains incomplete due to the complexity of the disease. Building on the research from the Pryzdial lab and others suggesting that PLTs and the PLT precursor cells, megakaryocytes (Megs), can replicate DENV, this dissertation explores direct mechanisms contributing to thrombocytopenia development through DENV-Meg and DENV-PLT interactions. The overarching hypothesis tested is that DENV directly induces protein synthesis in Megs and PLTs that contribute to thrombocytopenia. We investigated the presence of DENV-encoded nonstructural protein 1 (NS1) on the surface of Megs, contributing to innate immunity and the synthesis of new host proteins in infected PLTs that may lead to senescence, previously unexplored aspects. Our methods indeed demonstrated that NS1 cell-surface expression on Megs is targeted by DENV-patient-derived anti-NS1 antibodies, which triggered immune-mediated complement activation. Despite PLTs being enucleate, they possess the necessary systolic machinery for protein translation. Therefore, we employed a qualitative proteomics approach to identify DENV-induced de novo protein synthesis in PLTs. Including the expected appearances of the DENV-encoded polyprotein, this pilot approach revealed unique host protein synthesis, such as tropomyosin 3 (TPM3), fructose-bisphosphate aldolase A (ALDOA), glycoprotein Ib beta (GP1BB), AP-3 complex subunit delta 1 (AP3D1), and heat shock protein member 8 (HSPA8), and demonstrate the induction of critical PLT biochemical pathways. In summary, these findings shed light on novel molecular mechanisms potentially involved in thrombocytopenia and DENV-induced diseases, offering insights that could inform future therapeutic strategies and avenues for investigation.

Text

2024-10-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89465

Pathology and Laboratory Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/