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Genetic mapping indicates that VP4 is the rotavirus cell attachment protein in vitro and in vivo
1Department of Medicine and Microbiology and Immunology, Stanford University School of Medicine, California 94305, USA.
Abstract:
To identify the rotavirus protein which mediates attachment to cells in culture, viral reassortants between the simian rotavirus strain RRV and the murine strains EHP and EW or between the simian strain SA-11 and the human strain DS-1 were isolated. These parental strains differ in the requirement for sialic acid to bind and infect cells in culture. Infectivity and binding assays with the parental and reassortant rotaviruses indicate that gene 4 encodes the rotavirus protein which mediates attachment to cells in culture for both sialic acid-dependent and -independent strains. Using ligated intestinal segments of newborn mice and reassortants obtained between the murine strain EW and RRV, we developed an in vivo infectivity assay. In this system, the infectivity of EW was not affected by prior treatment of the enterocytes with neuraminidase, while neuraminidase treatment reduced the infectivity of a reassortant carrying gene 4 from RRV on an EW background more than 80% relative to the controls. Thus, VP4 appears to function as the cell attachment protein in vivo as well as in vitro.
Insights
Rotavirus gene 4 encodes the VP4 protein, which is responsible for attaching to host cells. This attachment mechanism is crucial for both sialic acid-dependent and -independent rotavirus infections in vitro and in vivo.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Rotavirus is a leading cause of severe diarrheal disease in infants and young children worldwide.
- The specific viral protein mediating rotavirus attachment to host cells has been a subject of investigation.
- Different rotavirus strains exhibit varying dependencies on sialic acid for cell binding and infection.
Purpose of the Study:
- To identify the specific rotavirus protein responsible for mediating cell attachment.
- To determine if this attachment protein functions similarly in both sialic acid-dependent and -independent infections.
- To investigate the role of the attachment protein in rotavirus infectivity in vivo.
Main Methods:
- Isolation of viral reassortants between different simian, murine, and human rotavirus strains.
- In vitro infectivity and binding assays using parental and reassortant rotaviruses.
- Development and utilization of an in vivo infectivity assay using ligated intestinal segments of newborn mice.
- Enzyme treatment (neuraminidase) of enterocytes to assess sialic acid-dependent binding.
Main Results:
- Viral reassortant analysis indicated that gene 4 encodes the rotavirus protein mediating cell attachment.
- This finding was consistent for both sialic acid-dependent and -independent strains in vitro.
- In vivo assays demonstrated that the gene 4 product (VP4) is essential for efficient rotavirus infection in the mouse intestinal model, with neuraminidase treatment significantly reducing infectivity of reassortants carrying the RRV gene 4.
Conclusions:
- The rotavirus protein encoded by gene 4, VP4, is the primary mediator of cell attachment.
- VP4 functions as the cell attachment protein in both in vitro and in vivo models.
- Understanding VP4's role in attachment is critical for developing antiviral strategies against rotavirus infections.