Isolation and RNA1 nucleotide sequence determination of a new insect nodavirus from Pieris rapae larvae in Wuhan city, China.

A new insect nodavirus is isolated from Pieris rapae larvae in Wuhan city, China and tentatively designated Wuhan nodavirus (WhNV). We here report the physicochemical characterization of WhNV and determine the nucleotide sequences of its larger segment of genome, RNA1. The results show that WhNV particles are isometric, non-enveloped, with a diameter of about 29nm. The virus has a major capsid protein and a minor capsid protein with estimated molecular mass of 40 and 44kDa, respectively. WhNV RNA1 is determined to be 3149nt long, containing a 1014-amino-acid open reading frame (ORF) encoding protein A with a calculated molecular mass of 114,608Da. The protein A shows 39 and 27% identity to its homologues in Pariacoto virus (PaV) and Striped jack necrosis nervous virus (SJNNV), respectively, but shows only 24% or less identity to its homologues in other insect Nodaviruses such as Nodamura virus (NoV), Black beetle virus (BBV), Boolarra virus (BoV) and Flock house virus (FHV). Predicted domains for six RNA-dependent RNA polymerase motifs and putative ORFs (protein B) are confirmed by sequence analysis of WhNV RNA1.