Classification and Properties of Togaviruses and Flaviviruses
المؤلف:
Stefan Riedel, Jeffery A. Hobden, Steve Miller, Stephen A. Morse, Timothy A. Mietzner, Barbara Detrick, Thomas G. Mitchell, Judy A. Sakanari, Peter Hotez, Rojelio Mejia
المصدر:
Jawetz, Melnick, & Adelberg’s Medical Microbiology
الجزء والصفحة:
28e , p559-560
2025-12-16
25
In the Togaviridae family, the Alphavirus genus consists of about 30 viruses 70 nm in diameter that possess a single stranded, positive-sense RNA genome (see Table 1). The envelope surrounding the particle contains two glycoproteins (see Figure 1). Alphaviruses often establish persistent infections in mosquitoes and are transmitted between vertebrates by mosquitoes or other blood-feeding arthropods. They have a worldwide distribution. All alphaviruses are antigenically related. The viruses are inactivated by acid pH, heat, lipid solvents, detergents, bleach, phenol, 70% alcohol, and formaldehyde. Most possess hemagglutinating ability. Rubella virus, classified in a separate genus in the Togaviridae family, has no arthropod vector and is not an arbovirus.
Table1. Classification and Properties of Some Arthropod-Borne and Rodent-Borne Viruses
Fig1. Electron micrographs of typical arboviruses and rodent-borne viruses. A: An alphavirus, Semliki Forest virus (Togaviridae). B: A representative member of Bunyaviridae, Uukuniemi virus. C: An arenavirus, Tacaribe virus (Arenaviridae). D: Ebola virus (Filoviridae). (Courtesy of FA Murphy and EL Palmer.)
The Flaviviridae family consists of about 70 viruses 40–60 nm in diameter that have a single-stranded, positive-sense RNA genome. Initially, the flaviviruses were included in the togavirus family as “group B arboviruses” but were moved to a separate family because of differences in viral genome organization. The viral envelope contains two glycoproteins. Some flaviviruses are transmitted among vertebrates by mosquitoes and ticks, but others are transmit ted among rodents or bats without any known insect vectors. Many have worldwide distribution. All flaviviruses are antigenically related. Flaviviruses are inactivated similarly to alphaviruses, and many also exhibit hemagglutinating ability. Hepatitis C virus, classified in a separate genus in the Flaviviridae family, has no arthropod vector and is not an arbovirus.
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