Genetic characterization of a novel picornavirus in turkeys (Meleagris gallopavo) distinct from turkey galliviruses and megriviruses and distantly related to the members of the genus Avihepatovirus

Abstract

Genetic characterization of a novel picornavirus in turkeys (Meleagris gallopavo) distinct from turkey galliviruses and megriviruses and distantly related to the members of the genus Avihepatovirus This study reports the metagenomic detection and complete genome characterization of a novel turkey picornavirus from faecal samples of healthy (1/3) and affected (6/8) commercial turkeys with enteric and/or stunting syndrome in Hungary. The virus was detected at seven of the eight farms examined. The turkey/M176-TuASV/2011/HUN genome (KC465954) was genetically different from the currently known picornaviruses of turkey origin (megriviruses and galliviruses), and showed distant phylogenetic relationship and common genomic features (e.g. uncleaved VP0 and three predicted and unrelated 2A polypeptides) to duck hepatitis A virus (DHAV) of the genus Avihepatovirus. The complete genome analysis revealed multiple distinct genome features like the presence of two in-tandem aphthovirus 2A-like sequence repeats with DxExNPG/P 'ribosomeskipping' sites (76 %, 23/30 amino acids identical), with the first aphthovirus 2A-like sequence being located at the end of the VP1 capsid protein (VP1/2A1 'ribosome-skipping' site). The phylogenetic analyses, low sequence identity (33, 32 and 36 % amino acid identity in P1, P2 and P3 regions) to DHAV, and the type II-like internal ribosome entry site suggests that this turkey picornavirus is related to, but distinct from the genus Avihepatovirus and it could be the founding member of a novel Avihepatovirus sister-clade genus. This is the third, taxonomically highly distinct picornavirus clade identified from turkeys exhibiting varied symptoms.

Comparative Complete Genome Analysis of Chicken and Turkey Megriviruses (Family Picornaviridae): Long 3′ Untranslated Regions with a Potential Second Open Reading Frame and Evidence for Possible Recombination

“…In this study, we confirmed all the cleavage sites predicted by Honkavuori et al (7) of megriviruses and mapped a previously unknown additional 2A cleavage site (7). In the chicken megriviruses, three putative mature 2A peptides were predicted, in similarity to the avian picornaviruses of the genus Avihepatovirus and the recently identified "Avisivirus" (6,10) in turkeys. The presence of a 82-aalong stretch located at the junction of VP1/2A terminating with a potential cleavage site in the THVs and turkey/B407-THV/2011/ HUN would result in the release of a fourth mature 2A, which makes the turkey megriviruses unique among the known picornaviruses, and members of genus Megrivirus may therefore represent an ancient group of picornaviruses showing multiple 2A genome features (6,34).…”

“…Most picornaviruses have only one mature 2A peptide/protein, although the number of picornaviruses with multiple potential 2As with mainly unknown function, e.g., duck hepatitis A virus (DHAV), turkey hepatitis virus (THV), swine pasivirus, bluegill picornavirus, turkey avisivirus, and pigeon mesivirus (6)(7)(8)(9)(10)(11), is increasing.…”

Metagenomics revealing new virus species in farm and pet animals and aquaculture

“…Boros et al (2012) identified and characterized a complete genome of novel picornavirus in a fecal sample from commercial turkey meat by using the 454 GS-FLX technology. Also Boros et al (2013) characterized another novel picornavirus, detected in Hungarian flocks of turkeys, which is distantly related to the members of the genus Avihepatovirus. Newly established genera of picornaviruses, avisivirus, megriviruses, and mesiviruses, were also described from turkey Ng et al, 2013a,b).…”

The fecal virome of domesticated animals

“…Novel picornaviruses with unexpected genome features had been characterized by pyrosequencing and were subsequently detected by RT-PCR in fecal samples collected from healthy and diseased turkey from several flocks in a Hungarian study. The phylogenetic analysis of the obtained sequences showed that although these viruses were most closely related to members of Avihepatovirus genus, it formed a distinct clade, provisionally named Avisivirus genus (Avihepatovirus sister-clade virus) [3].…”