Studies have investigated which viral proteins are responsible for membrane rearrangements seen in cells infected with flaviviruses. The NS4A of Kunjin virus induces the characteristic convoluted membranes and paracrystalline arrays seen in flavivirus infections. The NS4A-B protein also causes membrane rearrangement, but the highly condensed structures seen in infected cells are not produced until the NS2B-3 protease cleaves NS4A free from NS4B (Roosendaal et al., 2006). The NS4B then translocates to the nucleus (Westaway et al., 1997a). Interestingly, this contrasts with HCV where NS4B (and NS4A-B) (Egger et al., 2002; Konan et al., 2003) rather than NS4A is able to induce the membranous structures.
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