The orbivirus genus. Diversity, structure, replication and phylogenetic relationships.

The general properties of the orbiviruses have been examined at the physical, structural and molecular level. At the structural level, the orbiviruses (with the exception of the Kemerovo serogroup) appear similar. The replicative events are also similar, however differences in the ultrastructure of virus-specific structures and their association with components of the host cell have been observed. Further research in this area may be used to differentiate between the serogroups and even some serotypes, of orbiviruses. At the molecular level the properties of the genome can be used to determine relationships between members of the orbivirus genus. These relationships are revealed using a variety of techniques including serology and gene sequence analysis. Not only are the different serological responses to gene products present in the mature virus particle used for differential diagnosis, but the gene sequences themselves can also be utilized. Understanding of the relationships between these viruses is progressing to the point that insights into orbivirus molecular epidemiology is now possible.