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Glycoprotein gD of MDV lacks functions typical for alpha-herpesvirus gD homologues
V Zelník1, V Majerciak, D Szabová
1Institute of Virology, Slovak Academy of Sciences, Bratislava, Slovak Republic. viruzelo@nic.savba.sk
Abstract:
Glycoprotein D (gD) belongs to family of conserved structural proteins of alpha-herpesviruses. During productive infection of cells by herpes simplex virus 1 (HSV-1) gD has several important functions, is involved in virus penetration to and release from infected cells and is one of main targets of neutralizing antibodies. Similar functions are shared also by other alpha-herpesvirus gD homologues. Surprisingly, in previous studies it was found that MDV gD expression could not be detected during infection in vitro using immunological methods. In this study we have analyzed expression of MDV gD and its biological consequences. In vitro expression using rabbit reticulocyte lysate and/or overexpression in transfected cells showed that the second ATG codon is required for synthesis of mature, glycosylated gD. In addition, it was found that gD overexpression is neither toxic for transfected cells nor is involved in membrane fusion. After MDV infection of a proprietary cell line stably transfected with plasmid overexpressing MDV gD, no viral particles could be found in culture. On the other hand, cells overexpressing the MDV gD were sensitive to MDV infection in similar way as parental, non-transfected cells. From our study and results of other authors we propound the following conclusions: (i) MDV gD expression is blocked during in vitro infection at transcription level; (ii) MDV gD is lacking many important functions characteristic for other alpha-herpesvirus gD homologues; (iii) overexpression of single MDV gD does not result in production of mature infectious MDV particles.
Insights
Marek's disease virus (MDV) glycoprotein D (gD) expression is blocked at the transcription level during in vitro infection. Overexpression of MDV gD does not lead to mature virus production or confer protective functions.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- Glycoprotein D (gD) is a conserved structural protein in alpha-herpesviruses, crucial for viral entry, release, and antibody neutralization.
- Previous studies indicated undetectable Marek's disease virus (MDV) gD expression in vitro using immunological methods.
Purpose of the Study:
- To investigate the expression of MDV gD and its biological consequences.
- To understand the role of MDV gD in viral infection and replication.
Main Methods:
- In vitro expression analysis using rabbit reticulocyte lysate.
- Overexpression studies in transfected cells.
- Analysis of MDV infection in cells overexpressing MDV gD.
Main Results:
- The second ATG codon is essential for the synthesis of mature, glycosylated MDV gD.
- MDV gD overexpression is not toxic to cells and does not induce membrane fusion.
- No viral particles were detected after infecting cells overexpressing MDV gD, and these cells remained susceptible to infection.
Conclusions:
- MDV gD expression is transcriptionally blocked during in vitro infection.
- MDV gD lacks key functions observed in other alpha-herpesvirus gD homologues.
- Overexpression of MDV gD alone does not result in the production of mature, infectious MDV particles.