VZV Foundation - A Decade Of Leadership In The Fight Against VZV Infections

	Oral Presentation Abstracts: 29 [29] VARICELLA-ZOSTER VIRUS FUSION IS MEDIATED BY GLYCOPROTEINS gH, gL AND gB BUT ENHANCED BY gE *Lucie Maresova, TracyJo Pasieka & Charles Grose Department of Microbiology and Pediatrics, University of Iowa, Iowa City, USA Varicella-zoster virus (VZV) infection in cell culture is spread as infected cells fuse with neighboring uninfected cells, forming large syncytia. However, the mechanism by which VZV as well as other alphaherpesviruses mediate cell-to-cell fusion remains to be elucidated. A better understanding would be achieved by the availability of a model system, whereby fusion could be induced with a minimal set of proteins, in the absence of VZV infection. Our previous study using HeLa cells cotransfection system demonstrated direct involvement of VZV gH glycoprotein in cell membrane fusion. The gH fusogenic activity was dependent on coexpression with gL which is indispensable for gH maturation. Based on our other finding that the gL-associated chaperone function for gH was partially substituted by gE, we performed related experiment using gE, gB as well as gH-gL. In this study vaccinia virus (VV) recombinants expressing VZV glycoproteins gB, gE, gH, and gL were used. Moreover, various combinations of single or double VV recombinants were analyzed by laser scanning confocal microscopy to study which VZV glycoprotein played an active or supportive role in VZV cell membrane fusion. Our results indicated that not only the complex gH-gL, but glycoprotein gB by itself was capable of mediating polykaryocyte formation. Surprisingly, when both glycoproteins gB and gE were coexpressed by double recombinant VV-gE+gB, the syncytia were much larger than with gB alone. In other words, gE enhanced the fusogenic potential of VZV gB. In contrast to the either gH-gL or gE-gB complexes, glycoprotein gE alone was not sufficient to mediate fusion. Further the amount of fusion formation was quantified with Adobe Photoshop. Finally, all glycoprotein constructs were sequenced to assure that no mutations were introduced during cloning. In summary, in sharp contrast with HSV-1 results, the VZV gE protein plays a positive role in polykaryon formation. Corresponding Author: L. Maresova, Ph.D., Department of Microbiology and Pediatrics, University of Iowa, Steindler Bldg. 1612, Iowa City, Iowa 52242, USA

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VARICELLA-ZOSTER VIRUS FUSION IS MEDIATED BY GLYCOPROTEINS gH, gL AND gB BUT ENHANCED BY gE

*Lucie Maresova, TracyJo Pasieka & Charles Grose
Department of Microbiology and Pediatrics, University of Iowa, Iowa City, USA

Varicella-zoster virus (VZV) infection in cell culture is spread as infected cells fuse with neighboring uninfected cells, forming large syncytia. However, the mechanism by which VZV as well as other alphaherpesviruses mediate cell-to-cell fusion remains to be elucidated. A better understanding would be achieved by the availability of a model system, whereby fusion could be induced with a minimal set of proteins, in the absence of VZV infection. Our previous study using HeLa cells cotransfection system demonstrated direct involvement of VZV gH glycoprotein in cell membrane fusion. The gH fusogenic activity was dependent on coexpression with gL which is indispensable for gH maturation. Based on our other finding that the gL-associated chaperone function for gH was partially substituted by gE, we performed related experiment using gE, gB as well as gH-gL. In this study vaccinia virus (VV) recombinants expressing VZV glycoproteins gB, gE, gH, and gL were used. Moreover, various combinations of single or double VV recombinants were analyzed by laser scanning confocal microscopy to study which VZV glycoprotein played an active or supportive role in VZV cell membrane fusion. Our results indicated that not only the complex gH-gL, but glycoprotein gB by itself was capable of mediating polykaryocyte formation. Surprisingly, when both glycoproteins gB and gE were coexpressed by double recombinant VV-gE+gB, the syncytia were much larger than with gB alone. In other words, gE enhanced the fusogenic potential of VZV gB. In contrast to the either gH-gL or gE-gB complexes, glycoprotein gE alone was not sufficient to mediate fusion. Further the amount of fusion formation was quantified with Adobe Photoshop. Finally, all glycoprotein constructs were sequenced to assure that no mutations were introduced during cloning. In summary, in sharp contrast with HSV-1 results, the VZV gE protein plays a positive role in polykaryon formation.

Corresponding Author: L. Maresova, Ph.D., Department of Microbiology and Pediatrics, University of Iowa, Steindler Bldg. 1612, Iowa City, Iowa 52242, USA