D3178: (1st Place) RUVBL1 is an antiviral effector regulating maize mosaic virus accumulation in its insect vector Peregrinus maidis and positively regulates insect reproduction

RUVBL1 (TIP49, Pontin) encodes an ATPase of the AAA+ protein superfamily involved in several cellular functions, including chromatin remodeling, control of transcription, and cellular development (motility, growth, and proliferation). These functions are likely via target gene repression and potentially via DNA helicase activity. RUVBL1 has demonstrated broad antiviral activity against arthropod-borne animal viruses, including positive- and negative-sense single stranded RNA viruses. Maize mosaic virus (MMV) is an Alphanucleorhabdovirus transmitted in a circulative propagative manner by the corn planthopper Peregrinus maidis (Ashmead). Considering the antiviral role of RUVBL1 and its extensive cellular functions, here we evaluated the effect of RUVBL1 knockdown on MMV accumulation and the physiology of its insect vector P. maidis. RUVBL1 knockdown was associated with increased MMV accumulation in the insect vector, with significantly higher virus titer observed at 12, 15 and 18 days after dsRNA and virion injection. RUVBL1 knockdown was correlated with visible morphology changes in female insects with significant increases in body mass observed at eight- and 12-days post dsRNA injection. Ovary morphology was significantly affected in adult females with RUVBL1 knockdown, with no mature oocytes observed at eight and 12 days after knockdown. Due to ovary malformation, significantly fewer eggs were laid at 12 days post-injection, and dramatic reductions in egg hatching were observed at four, eight and 12 days after RUVBL1 knockdown, in comparison to controls injected with dsGFP. These results suggest that RUVBL1 has an antiviral role against phytoarboviruses and extends its function as a positive regulator of P. maidis reproduction.