Genogroup I picobirnaviruses in pigs: evidence for genetic diversity and relatedness to human strains

Abstract

Picobirnaviruses (PBVs) are small, non-enveloped viruses with a bisegmented double-stranded RNA genome. Their pathogenic potential, ecology, and evolutionary features are largely unexplored. Here, we describe the molecular analysis of porcine PBVs identified in the intestinal content of dead pigs. Six of 13 positive samples were cloned and then subjected to single-strand conformation polymorphism analysis and nucleotide sequencing. All clones belonged to genogroup I PBVs and almost all clones clustered on separate branches from human strains. A single strain shared a notably close genetic relationship with a Hungarian human PBV strain (89.9 nt and 96.4 % aa identity). Genetic diversity was also observed among strains identified in mixed infections. Single point mutations and deleterious mutations within highly related strains suggested that PBVs exist as quasispecies in the swine alimentary tract. Clones with complete sequence identities originating from different animals suggested effective animal-to-animal transmission of the virus. Our findings indicate that infection with genogroup I PBVs is common in pigs.

Animal Picobirnavirus

“…Similarly, PBVs have also been detected as sole pathogens in diarrhoeic animals [9,60,67] and with other known and established enteric pathogens [2,4,83]. They are still classified as 'opportunistic diarrhoeagenic pathogen', since they have been detected from immunocompromised patients and patients with prolonged immunosuppressive treatment who suffered from diarrhoea than non-diarrhoeic controls [18,38,39,41,42,44,75].…”

Detection and Molecular Characterization of Porcine Picobirnavirus in Feces of Domestic Pigs from Kolkata, India

“…Genogroup I PBVs detected and sequenced from pigs in Hungary [2] and Venezuela and Argentina [5,22], were observed to be closely related to human genogroup I PBVs. These results strongly suggest that PBV strains may circulate in the shared environment where humans and pigs live.…”

“…PBVs were detected from immunocompromised patients [24] in which implied to be ''opportunistic pathogens'' and have also been detected from asymptomatic hosts [11]. The question whether PBV is an 'innocuous agent' of the intestine remains to be investigated [2,7,19,31,35].…”

“…PBVs are known to cause chronic diarrhoea with prolonged shedding of the virus in humans [24] and various animals [30] besides frequent infections among piglets [5,29]. Moreover, the presence of genogroup I PBVs in humans and different animals, rodents and reptiles, suggests that any specific genogroup is not restricted to specific host [2,3,5,12,16,19,31].…”

“…Evidence for genetic relatedness was reported between human and animal PBVs or vice versa [2,5,[16][17][18]22] from around the globe. Genogroup I PBVs detected and sequenced from pigs in Hungary [2] and Venezuela and Argentina [5,22], were observed to be closely related to human genogroup I PBVs.…”