Structural insight into African horsesickness virus infection
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Date
2012Author
Manole, Violeta
Van Dijk, Alberdina A.
Laurenmäki, Pasi
Van Wyngaardt, Wouter
Potgieter, Christiaan A.
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African horsesickness (AHS) is a devastating disease of horses. The disease is caused by the double-stranded RNA-containing
African horsesickness virus (AHSV). Using electron cryomicroscopy and three-dimensional image reconstruction, we determined
the architecture of an AHSV serotype 4 (AHSV-4) reference strain. The structure revealed triple-layered AHS virions enclosing
the segmented genome and transcriptase complex. The innermost protein layer contains 120 copies of VP3, with the viral
polymerase, capping enzyme, and helicase attached to the inner surface of the VP3 layer on the 5-fold axis, surrounded by double-
stranded RNA. VP7 trimers form a second, T 13 layer on top of VP3. Comparative analyses of the structures of bluetongue
virus and AHSV-4 confirmed that VP5 trimers form globular domains and VP2 trimers form triskelions, on the virion surface.
We also identified an AHSV-7 strain with a truncated VP2 protein (AHSV-7 tVP2) which outgrows AHSV-4 in culture. Comparison
of AHSV-7 tVP2 to bluetongue virus and AHSV-4 allowed mapping of two domains in AHSV-4 VP2, and one in bluetongue
virus VP2, that are important in infection. We also revealed a protein plugging the 5-fold vertices in AHSV-4. These results shed
light on virus-host interactions in an economically important orbivirus to help the informed design of new vaccines.
URI
http://hdl.handle.net/10394/17552http://jvi.asm.org/content/86/15/7858
http://dx.doi.org/10.1128/JVI.00517-12