Structure and Function of Bluetongue Virus and its Proteins
from: Segmented Double-stranded RNA Viruses: Structure and Molecular Biology (Edited by: John T. Patton). Caister Academic Press, U.K. (2008)
The members of Orbivirus genus within the Reoviridae family are arthropod-borne viruses and are responsible for high morbidity and mortality in ruminants. Bluetongue virus (BTV) which causes disease in livestock (sheep, goat, cattle) has been in the forefront of molecular studies for the last three decades and now represents the best understood orbivirus at the molecular and structural levels. BTV, like other members of the family, is a complex non-enveloped virus with seven structural proteins and a RNA genome consisting of 10 variously sized double-stranded (ds) RNA segments. This article will be centred on the molecular dissection of BTV with a view to understanding the role of each protein in the virus replication cycle. Data obtained from studies over a number of years has defined the key players in BTV entry, replication, assembly and exit and has increasingly found roles for host proteins at each stage. Specifically, it has been possible to determine the complex nature of the virion through 3D Cryo-electron microscopy (EM) reconstructions (diameter ~ 800 Å); the atomic structure of proteins and the internal capsid (~ 700 Å, the first large highly complex structure ever solved); the definition of the virus encoded enzymes required for RNA replication; the ordered assembly of the capsid shell and the protein sequestration required for it; and the role of host proteins in virus entry and virus release. These areas are important in themselves for BTV replication but they also indicate the pathways that related viruses, which includes viruses that are pathogenic to man and animals, might also use providing an informed starting point for intervention or prevention read more ...