Genetic characterization of two novel picornaviruses from birds, white-tailed eagle (Haliaeetus albicilla) and pied avocet (Recurvirostra avosetta) in Hungary

In this study, two novel picornaviruses (eagle/WE6/HUN/2014, PV454551-PV454552 and avocet/PA12/HUN/2018, PV454553) were detected in white-tailed eagle (Haliaeetus albicilla) and pied avocet (Recurvirostra avosetta) in Hungary, and characterized by next generation sequencing, RT-PCR and Sanger sequencing methods. The complete polyprotein coding genomes were 6,573 and 6,567 nt long and had the genome organization 5′UTR^IRES-III-[VP4-VP2-VP3-VP1-2A-2B-2C^hel-3A-3B^VPg-3C^pro-3D^pol]-3′UTR-poly(A)n. The P1 and the 3C^proproteins of the eagle/WE6/HUN/2014 showed 47.9% and 62.4% aa sequence identities to the corresponding proteins of the picornavirus (MT138036) from a little egret metagenome, respectively. The 2C^hel/3D^polhad 44.1%/41% aa identity to the corresponding proteins of bat-origin picornaviruses (OR867633 and KX420952). The P1 protein of the avocet/PA12/HUN/2018 had 53% aa sequence identity to the P1 protein of crane70contig328 (OQ423840) from red-crowned crane metagenome; the 2C^hel, 3C^proproteins had 52.6%, 52.3% aa sequence identity to the corresponding proteins of picornavirus (MT138035) from bird metagenome and 3D^polhad 43.2% aa identity to the 3D^polof the picornavirus (MT138036) from a little egret metagenome, respectively. The 3’UTR of avocet/PA12/HUN/2018 contained two repetitive nt sequence motifs (the 17-nt-long Motif-1 at five times forming a secondary RNA structure and the 9-nt-long Motif-2 at two times). The eagle/WE6/HUN/2014 and avocet/PA12/HUN/2019 represent the founding members of two potential novel bird-origin picornavirus species and even genera in the subfamilyHeptrevirinae(familyPicornaviridae).