Related Experiment Video
Updated: Nov 29, 2025
Using Reverse Genetics to Manipulate the NSs Gene of the Rift Valley Fever Virus MP-12 Strain to Improve Vaccine Safety and Efficacy
Published on: November 1, 2011
Functional advantages of triplication of the 3B coding region of the FMDV genome
Oluwapelumi O Adeyemi1,2, Joseph C Ward1, Joseph S Snowden1
1School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.
Abstract:
For gene duplication to be maintained, particularly in the small genomes of RNA viruses, this should offer some advantages. We have investigated the functions of a small protein termed VPg or 3B, which acts as a primer in the replication of foot-and-mouth disease virus (FMDV). Many related picornaviruses encode a single copy but uniquely the FMDV genome includes three (nonidentical) copies of the 3B coding region. Using sub-genomic replicons incorporating nonfunctional 3Bs and 3B fusion products in competition and complementation assays, we investigated the contributions of individual 3Bs to replication and the structural requirements for functionality. We showed that a free N-terminus is required for 3B to function as a primer and although a single 3B can support genome replication, additional copies provide a competitive advantage. However, a fourth copy confers no further advantage. Furthermore, we find that a minimum of two 3Bs is necessary for trans replication of FMDV replicons, which is unlike other picornaviruses where a single 3B can be used for both cis and trans replication. Our data are consistent with a model in which 3B copy number expansion within the FMDV genome has allowed evolution of separate cis and trans acting functions, providing selective pressure to maintain multiple copies of 3B.
Insights
Foot-and-mouth disease virus (FMDV) uniquely uses multiple copies of the VPg (3B) protein for replication. More copies enhance viral replication, with distinct cis and trans functions evolving for multiple 3B proteins.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Gene duplication in RNA viruses is rare and suggests functional advantages.
- Foot-and-mouth disease virus (FMDV) is unique among picornaviruses for possessing three copies of the VPg (3B) protein-coding region.
- The VPg (3B) protein functions as a primer for viral RNA replication.
Purpose of the Study:
- To investigate the functional contributions and structural requirements of individual VPg (3B) protein copies in FMDV replication.
- To understand the selective pressures maintaining multiple VPg (3B) copies in the FMDV genome.
Main Methods:
- Utilized sub-genomic replicons with nonfunctional 3B proteins and 3B fusion products.
- Employed competition and complementation assays to assess VPg (3B) functionality.
- Investigated requirements for both cis and trans replication.
Main Results:
- A free N-terminus is essential for VPg (3B) to act as a primer.
- While one VPg (3B) copy supports genome replication, additional copies confer a competitive advantage, up to a point.
- A minimum of two VPg (3B) copies are required for trans replication, unlike other picornaviruses.
Conclusions:
- VPg (3B) copy number expansion in FMDV likely facilitated the evolution of separate cis and trans replication functions.
- This functional specialization provides a selective advantage for maintaining multiple VPg (3B) copies in the FMDV genome.
More Related Videos
12:20Bacterial Artificial Chromosomes: A Functional Genomics Tool for the Study of Positive-strand RNA Viruses
Published on: December 29, 2015
07:24Single-Cell Multiplexed Fluorescence Imaging to Visualize Viral Nucleic Acids and Proteins and Monitor HIV, HTLV, HBV, HCV, Zika Virus, and Influenza Infection
Published on: October 29, 2020
Related Concept Videos
01:26DNA Bacteriophages
01:29Modern Molecular Taxonomy
02:37Gene Duplication and Divergence
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are...