The nucleotide sequence of sacbrood virus of the honey bee: an insect picorna-like virus

We have determined the nucleotide sequence of sacbrood virus (SBV), which c auses a fatal infection of honey bee larvae. The genomic RNA of SBV is long er than that of typical mammalian picornaviruses (8832 nucleotides) and con tains a single, large open reading frame (179-8752) encoding a polyprotein of 2858 amino acids. Sequence comparison with other virus polyproteins reve aled regions of similarity to characterized helicase, protease and RNA-depe ndent RNA polymerase domains; structural genes were located at the 5' termi nus with non-structural genes at the 3' end. Picornavirus-like agents of in sects have two distinct genomic organizations; some resemble mammalian pico rnaviruses with structural genes at the 5' end and non-structural genes at the 3' end, and others resemble caliciviruses in which this order is revers ed; SBV thus belongs to the former type. Sequence comparison suggested that SBV is distantly related to infectious flacherie virus (IFV) of the silk w orm, which possesses an RNA of similar size and gene order.