Genetic characterization of two novel megriviruses in geese

Two goose megriviruses (W18 and HN56) were detected and sequenced. Both viruses possessed megrivirus-like genomic features, including unusually long genomes (9840 and 10 101 nt). W18 and HN56 were very similar to duck megrivirus (DMV) in the P2 and P3 regions, but much less similar in the P1 and 2A1 regions. HN56 may be a potential recombinant virus, with a distinct P1 region possibly originating from an unknown picornavirus. W18 may represent a novel type of DMV, showing a P1 sequence identity of 67 %. Similar levels (64-68 %) of P1 sequence identity were also displayed by melegrivirus A with W18 and DMV, demonstrating an equal genetic separation of the capsid region among W18, DMV and melegrivirus A. For the 2A1 region, the divergence among W18, HN56 and DMV was remarkable, involving point mutations and a long insertion/deletion. The present work contributes to the understanding of unique features and phylogeny of megriviruses.