Sequence heterogeneity among human picobirnaviruses detected in a gastroenteritis outbreak

Abstract

Human picobirnaviruses characterised in this study were serendipitously detected in a non-bacterial gastroenteritis outbreak when specimens were examined for the presence of human rotaviruses using polyacrylamide gel electrophoresis. Of ten stool samples sent for virological examination, two, three, and one specimens were positive for human caliciviruses, picobirnaviruses, and both viruses, respectively. Partial sequences of the RNA-dependent RNA polymerase gene were determined for three picobirnavirus-positive samples. The sequence identity among these three strains was 60% to 65% for the nucleic acid and 64% to 70% for the deduced amino acid sequences. Phylogenetic analysis revealed that each of the three strains clustered with strains identified in geographically separate areas. In contrast, human calicivirus strains co-incidentally identified, showed complete nucleotide sequence identity. These findings demonstrate a lack of common exposure to or point of source for picobirnavirus infection, suggesting that the outbreak was caused by human caliciviruses. Further studies are needed to determine the etiologic role and to establish the taxonomic basis of picobirnaviruses.

Animal Picobirnavirus

“…It has been suggested that segmented nature of Picobirnavirus genome renders them as potential candidates for segment reassortment, which could explain their highly heterogenous nature [3,4]. In another study, it was stated that the segmented viruses have the tendency to reassort, and often such reassortments may lead to emergence of virulent progeny [62].…”

“…It has been suggested that segmented nature of human PBV genome renders it as a potential candidate for segment reassortment, which could explain the highly heterogenous nature [3].…”

Molecular Characterization of Porcine Picobirnaviruses and Development of a Specific Reverse Transcription-PCR Assay

“…PBV have been identified in fecal samples of humans practically worldwide (2,4,5,8,10,20,23,25,27), in feces of a wide variety of farm mammals and birds, including pigs (3,9,12,21,26), calves (7), rabbits (11,14,22), and chickens (19), and even in feces of wild animals keep in captivity (16,24,30). Despite the numerous reports of the presence of PBV in fecal samples from vertebrates, the pathogenicity of these viruses has not been established.…”

“…Epidemiological studies carried out in several countries have made it clear that human PBV strains are highly diverse and can be grouped into at least two genogroups (2,5,23,27). PBV sequences from pigs have recently been described (3), being genetically related to the human genogroup I.…”

“…Clone PBV2-POR was left out of the analysis, since mostly PBV sequences containing RNA polymerase motif 1 were available in GenBank. The phylogenetic analysis included sequences from 19 human strains, 18 representative of genogroup I (2,23,27,29), and 43 recently reported sequences from porcine picobirnaviruses isolated in Hungary, also classified as genogroup I (3). Figure 1 shows a phylogenetic tree based on a 168-nucleotides fragment which included clones PBV1-POR, PVB3-POR, and PBV4-POR.…”