Characterization Of The Entry Mechanisms Of JunÍN Arenavirus

Abstract

Junín Arenavirus causes Viral Hemorrhagic Fever with a 30% fatality rate in those infected. Yet the exact pathogenesis of disease is still unknown. To date, the only known human receptor is transferrin (TfR1). TfR1 is located basolaterally in the lung epithelium and unavailable to inhaled virus particles. One proposed mechanism for viral infection and pathogenesis is that antigen presenting cells may interact with the virus and become infected, Here we show that immature dendritic cells (DCs) can interact with the Junín pseudovirus virus (JUNVpp) but do not become productively infected. Instead they harbor the virus like a Trojan Horse in a process called transinfection. Dendritic cells have both the TfR1 receptor and an antigen processing receptor, DC-SIGN. The virus associates with both receptors and early endosomal compartment but was not seen associating with late endosomal compartments where fusion of the viral envelope with the host cell membrane would normally occur. Invivo, a trans-infected DC would travel to a lymph node. We utilized a primary human sinusoidal endothelial cell (HHSEC) which possesses some of the same receptors as lymph nodes, mainly DC-SIGN, L-SIGN and LSECtin. JUNVpp can utilize LSECtin as a receptor. DC-SIGN and L-SIGN also seem to function as entry receptors in the context of HHSEC cells though to a lesser extent than TfR1 and LSECtin. iii Since viruses can interact with receptors through glycosylation sites on the glycoprotein we analyzed each glycosylation site on the GP-1 portion of the glycoprotein by mutating the critical asparagine to a glutamine. The N-linked sites are not involved in binding and entry with the TfR1 receptor and deficits in entry can be attributed to structural changes or inability to use a C-type lectin as a receptor. All sites were important for maintaining structure as determined by reduced ability of the mutants to associate with the TfR1 receptor. Some mutants had defects in cleavage and were not incorporated into the virion. Our results suggest that N-linked glycosylation sites are critical for virus structure and eventual binding with the C-type lectins LSECtin, DC-SIGN and L-SIGN. iv