Hiren V. Patel
B.A. Boston University, 2010

1st Year Graduate Student

Advisor: Jessica Seeliger, Ph.D.

Department: Pharmacological Sciences

Graduate Program: Molecular Genetics & Microbiology

Title:  Mechanism of Envelope Glycoprotein Independent Interactions of Enveloped RNA Viruses with Dendritic Cells

Hiren V. Patel & Dr. Suryaram Gummuluru
Department of Microbiology, Boston University School of Medicine

Abstract (Undergraduate):

          Dendritic cells (DCs) have been proposed to be the initial targets for enveloped RNA viruses such as human immunodeficiency virus-1 (HIV-1). Though fusion and productive entry of HIV-1 particles within CD4+ T cells requires the virus envelope glycoprotein gp120, capture of HIV-1 particles by DCs can occur in a gp120-independent manner. HIV-1 capture is dependent on interactions of glycosphingolipids (GSLs) present in the virus particle membrane with a yet-to-be identified DC-specific receptor. GSL incorporation into HIV-1 particles is dependent on budding of virus particles from GSL-enriched lipid rafts plasma membrane microdomains. It has been seen that the Marburg (MARV), Nipah (NiV), and Hendra (HeV) virus also assemble and bud from GSL-enriched lipid rafts; therefore, we want to determine if capture of these viruses by DCs could also occur in a glycoprotein independent manner. The expression of eGFP-fused versions of matrix proteins for HIV-1 (HIV-1 Gag), Marburg virus (MARV VP40), Nipah virus (NiV M), and Hendra virus (HeV M) within HEK293T cells produces non-infectious virus like particles (VLPs), which are morphologically indistinguishable from infectious virus particles. Immunofluorescent deconvolution microscopy of transfected HEK293T cells demonstrated that NiV M-eGFP and HeV M-eGFP proteins, but not VP40-eGFP bud from similar regions, which are high in GM1, as HIV-1 Gag-eGFP. Coexpression of VP40-eGFP and MARV glycoprotein (GP) allowed for assembly and budding from high GM1 regions located on cell membrane. Interestingly, NiV M-eGFP and HeV M-eGFP VLPs, but not VP40-eGFP VLPs were captured by mDCs, and their capture could be competitively inhibited by HIV-1 Gag-Cherry VLPs. GSL-deficient VLPs were generated using a competitive inhibitor of glucosylceramide synthase, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP). With the exception of VP40-eGFP, GSL-deficient VLPs for HIV-1 Gag-eGFP, HeV M-eGFP, and NiV M-eGFP had a significantly lower binding than their respective GSL-enriched VLPs. Taken together, this suggests that assembly and budding of divergent enveloped RNA viruses is possibly conserved and might rely on microdomains with a high density of GSLs. Furthermore, similar to HIV-1, capture of Hendra and Nipah viruses by DCs can also occur in a glycoprotein independent manner, while Marburg virus relies on another mechanism for viral capture by mDCs