Abstract
In recent years, ultrastructural studies of viral surface spikes from three different genera within the Bunyaviridae family have revealed a remarkable diversity in their spike organization. Despite this structural heterogeneity, in every case the spikes seem to be composed of heterodimers formed by Gn and Gc envelope glycoproteins. In this review, current knowledge of the Gn and Gc structures and their functions in virus cell entry and exit is summarized. During virus cell entry, the role of Gn and Gc in receptor binding has not yet been determined. Nevertheless, biochemical studies suggest that the subsequent virus-membrane fusion activity is accomplished by Gc. Further, a class II fusion protein conformation has been predicted for Gc of hantaviruses, and novel crystallographic data confirmed such a fold for the Rift Valley fever virus (RVFV) Gc protein. During virus cell exit, the assembly of different viral components seems to be established by interaction of Gn and Gc cytoplasmic tails (CT) with internal viral ribonucleocapsids. Moreover, recent findings show that hantavirus glycoproteins accomplish important roles during virus budding since they self-assemble into virus-like particles. Collectively, these novel insights provide essential information for gaining a more detailed understanding of Gn and Gc functions in the early and late steps of the hantavirus infection cycle.
Highlights
Hantaviruses are human pathogens that are distributed worldwide and classified by the NIH as categoryA priority pathogens
Their transmission to humans can cause the development of two severe diseases; in Europe and Asia prototype members of the genus, such as Hantaan virus (HTNV), Puumala virus (PUUV) or Dobrava virus (DOBV), are associated with hemorrhagic fever with renal syndrome (HFRS), causing mortality rates that vary from 0.3% to 10%
In this review we summarize the current progress in understanding hantavirus envelope glycoprotein functions and highlight recent insights into glycoprotein structures and their possible arrangements on hantavirus particles
Summary
Unlike other viruses from this family, which are transmitted by arthropods, hantaviruses are harbored by small mammals, mainly rodents [2] Their transmission to humans can cause the development of two severe diseases; in Europe and Asia prototype members of the genus, such as Hantaan virus (HTNV), Puumala virus (PUUV) or Dobrava virus (DOBV), are associated with hemorrhagic fever with renal syndrome (HFRS), causing mortality rates that vary from 0.3% to 10%. Such a viral envelope projects the glycoproteins as spike associations and is acquired by the budding of viral ribonucleocapsids through a cellular membrane in which the viral glycoproteins are inserted This step enables enveloped viruses to cross the membranous barriers of cells unnoticed, a process that together with secretion allows the exit of virus particles from infected cells [5,6]. In this review we summarize the current progress in understanding hantavirus envelope glycoprotein functions and highlight recent insights into glycoprotein structures and their possible arrangements on hantavirus particles
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