The 3′ untranslated region of tick-bome flaviviruses originated by the duplication of long repeat sequences within the open reading frame

Comparative alignment of the 3 ' untranslated regions (3 ' UTRs) of tick-bome flaviviruses has previously revealed short direct repeat sequences about 25-70 nucleotides long [Gritsun, T.S., Venugopal, K., Zanotto, P.M., Mikhailov, M.V, Sall, A.A., Holmes, E.C., Polkinghome, I., Frolova, TV, Pogodina, V.V, Lashkevich, VA., Gould, E.A., 1997. Complete sequence of two tick-bome flaviviruses isolated from Siberia and the UK: analysis and significance of the 5 ' and 3 '-UTRs. Virus Res. 49 (1) 27-39-, Wallner, G., Mandl, C.W., Kunz, C.. Heinz, F.X., 1995. The flavivirus 3 '-noncoding region: extensive size heterogeneity independent of evolutionary relationships among strains of tick-borne encephalitis virus. Virology, 213 (1) 169-178]. We now show that these short sequences appear to have originated from longer repeat sequences (LRSs) that are present both in the 3 ' UTR and the open reading frame of the genome. We propose that the 3 ' UTR, and possibly the open reading frame, evolved through multiple duplications, deletions and imitations of a primordial sequence element. (c) 2006 Elsevier Inc. All rights reserved.