Figure 1 (Left) Diagrammatic representation of a bunyavirus virion in cross-section. The surface spikes comprise two glycoproteins termed G1 and G2. The three helical nucleocapsids are circular and comprise one each of the unique ssRNA segments (L, large; M, medium; S, small) encapsidated by N protein and associated with the L protein (Courtesy of R. Pettersson). (Right). Cryoelectron micrograph of particles of California encephalitis virus (CEV) strain La Crosse virus, taken with large defocus value which demonstrates the glycoprotein spikes (Courtesy of B.V.V. Prasad; see Elliott, Schmaljohn and Collett, 1991).
Figure 2 Coding strategies of genome segments of members of the family Bunyaviridae. Genomic RNAs are represented by thin lines (the number of nucleotides is given above the line) and mRNAs are shown as arrows ( indicates host derived primer sequence at 5-end, indicates 3-end). Gene products, with their Mr size ( 103), are represented by solid rectangles. (Modified from Elliott, 1996.)
Figure 3 Transcription and replication scheme of genome segments of members of the family Bunyaviridae for a negative-strand segment (left) and for an ambisense segment (right). The genome RNA and the positive-sense viral complementary RNA, known as anti-genome RNA, are only found as ribonucleoprotein complexes and are encapsidated by N protein. The mRNA species contain host derived primer sequences at their 5-ends () and are truncated at the 3 end relative to the vRNA template; the mRNAs are not polyadenylated.
Figure 4 Electron micrograph of negatively stained particles of California encephalitis virus (CEV) strain La Crosse virus. The bar represents 100 nm. (Courtesy of D.H.L. Bishop.)
Figure 5 Electron micrograph of negatively stained particles of Hantaan virus (HTNV). The bar represents 100 nm. (Courtesy of C.S. Schmaljohn.)
Figure 6 Electron micrograph of negatively stained particles of Crimean-Congo hemorrhagic fever virus (CCHFV). The bar represents 100 nm.
Figure 7 (Left) Electron micrograph of negatively stained particles of Uukuniemi virus (UUKV). The bar represents 100 nm. (Right) Cryo-electron micrograph of purified UUKV. (Both courtesy of C-H. von Bornsdorff.)
Figure 8 Electron micrograph of negatively stained particles of Tomato spotted wilt virus (TSWV). The bar represents 100 nm. (Courtesy of J. van Lent.)
Figure 9 Phylogenetic tree of aligned polymerase domains from the L proteins of members of the family Bunyaviridae and from analogous proteins of other segmented (Arenaviridae, Orthomyxoviridae) and non-segmented (Paramyxoviridae) negative-strand RNA viruses. The tree was constructed by the neighbor-joining method. Figures on the branches represent percentages of trees containing each cluster out of 500 bootstrap replicates. Branch lengths are proportional to the genetic distance. The polymerase domain from Human respiratory syncytial virus (HRSV) is used as an outgroup. (Redrawn from Marriott and Nuttall, 1996.)
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