UNASSIGNED: Lepidopteran innate immune response against RNA viruses remains poorly understood, while in other insects several studies have highlighted an essential role for the exo-RNAi pathway in combating @entity1800 . Here, by employing deep sequencing technology for viral small RNA (vsRNA) assessment, we provide evidence that exo-RNAi is operative in the @entity12638 @entity12638 against both persistent and pathogenic infection of @entity12638 cytoplasmic polyhedrosis virus (BmCPV) which is characterized by a segmented dsRNA genome. Further, we show that @entity68273 predominantly targets viral dsRNA and produces 20 nt vsRNAs, whereas an additional pathway is responsive to viral mRNA derived from segment 10. Importantly, vsRNA distributions, which define specific hot- and cold-spot profiles for each viral segment, are to a considerable degree overlapping between @entity68273 -related (19-21 nt) and @entity68273 -unrelated vsRNAs suggesting a common origin for these profiles. We found a degenerate motif significantly enriched at the cut sites of vsRNAs of various lengths which link an unknown ribonuclease to the origins of vsRNAs biogenesis and distribution. Accordingly, the indicated RNase activity may be an important early factor for the host's antiviral defense in Lepidoptera. IMPORTANCE: This work contributes to the elucidation of the lepidopteran antiviral response against @entity778 ( @entity24715 ; Reoviridae) and highlights the importance of vsRNA analysis for getting insights into host-pathogen interactions. Three vsRNA pathways are implicated in antiviral defense. For dsRNA, two pathways are proposed, either based on @entity68273 cleavage to generate 20 nt vsRNAs, or based on the activity of an uncharacterized endoRNase that cleaves the viral RNA substrate at a degenerate motif. The analysis indicates also the existence of a degradation pathway that targets the (+)-strand of segment 10.

Viral small RNA analysis of @entity12638 larval midgut during persistent and pathogenic cytoplasmic polyhedrosis XXXX .

@entity778 :: ('MESH:D015658', 'Disease') :: ['infection of segmented dsRNA virus'] @entity12638 :: ('7091', 'Species') :: ['Bombyx mori', 'silkworm', 'B. mori'] @entity1800 :: ('MESH:D014777', 'Disease') :: ['viral infection'] @entity24715 :: ('10788', 'Species') :: ['CPV'] @entity68273 :: ('100499206', 'Gene') :: ['Dicer-2']
@entity778 :: (MESH:D015658,Disease) :: ['virus infection']
