Transmission electron micrograph (TEM) of the Tribec virus, a member of the genus Orbiviruses, which is one of nine genera of the virus family known as the Reoviridae. As an arbovirus, Tribec virus is spread through the bite of insect vectors such as mosquitoes, ticks, and sandflies. As an Orbivirus, the Tribec virus is named for the "doughnut-shape" of the many capsomeres, which together comprise its bilaminar capsid layer. The two capsid layers surround an inner core of ten double-stranded RNA segments. The oribiviruses primarily affects animals, causing bluetongue disease, African horse sickness, and epizootic hemorrhagic deer fever.