Unusual characteristics of dicistrovirus-derived small RNAs in the small brown planthopper, Laodelphax striatellus

In this study, sequences of small RNA (sRNA) libraries derived from the insect vector Laodelphax striatellus were assembled into contigs and used as queries for database searches. A large number of contigs were highly homologous to the genome sequence of an insect dicistrovirus, himetobi P virus (HiPV). Interestingly, HiPV-derived sRNAs had a wide size distribution, and were relatively abundant throughout the 18-30 nt size range with only a slight peak at 22 nt. HiPV sRNAs had a strong bias towards the sense strand, whilst the antisense sRNAs were predominantly 21 and 22 nt. HiPV sRNAs do not have the typical features of PIWI-interacting RNAs, but their 39 ends were preferentially cleaved at UA-rich sequences. Our data suggest that HiPV sRNAs may be derived both from activities of the RNA interference pathway and from cleavage of the viral genome by other host RNases.