Picobirnavirus Strains Research Articles

Circulation of picobirnavirus in Neotropical free-ranging mammals.

Picobirnavirus (PBV) is a family of non-enveloped double-stranded RNA viruses with bisegmented genomes. Segment 1 encodes the capsid protein and segment 2 encodes RNA-dependent RNA polymerase. They exhibit high genomic heterogeneity and infect a wide range of vertebrate hosts, including humans. The objective of this study was to expand our knowledge of the circulation of PBV in free-living animals from two regions (Brazil and Argentina) of the Atlantic Forest. Fecal samples were analyzed from free-living animals: tapir, brocket deer, peccary, and different species of rodents and marsupials. A total of 133 samples were collected and analyzed by RT-PCR, of which 44 (33.08%) were PBV-positive. Nine amplicons were sequenced, five species from Argentina and four from Brazil, and phylogenetic analysis was performed. The nucleotide and amino acid identities of the PBV strains detected in animals from Argentina and Brazil were between 66.3% and 82.5% and between 55.3% and 74.2%, respectively. The analysed strains presented conserved nucleotide blocks without distinction of the host species. The phylogenetic tree showed that PBV strains from Atlantic Forest animals belonging to genogroup I were grouped into different clusters, without defining groups according to host species (human or animal) or the geographical area of detection. This is the first study on PBV in free-living animals in the Atlantic Forest. Our analysis suggested that PBV strains can infect different animal species, leading to PBV transmission between animals and humans. This reinforces the hypothesis of previous crossover points in the ecology and evolution of heterologous PBV strains.

Metagenome-Assembled Viral Genomes Analysis Reveals Diversity and Infectivity of the RNA Virome of Gerbillinae Species.

Rodents are a known reservoir for extensive zoonotic viruses, and also possess a propensity to roost in human habitation. Therefore, it is necessary to identify and catalogue the potentially emerging zoonotic viruses that are carried by rodents. Here, viral metagenomic sequencing was used for zoonotic virus detection and virome characterization on 32 Great gerbils of Rhombomys opimus, Meriones meridianus, and Meiiones Unguiculataus species in Xinjiang, Northwest China. In total, 1848 viral genomes that are potentially pathogenic to rodents and humans, as well as to other wildlife, were identified namely Retro-, Flavi-, Pneumo-, Picobirna-, Nairo-, Arena-, Hepe-, Phenui-, Rhabdo-, Calici-, Reo-, Corona-, Orthomyxo-, Peribunya-, and Picornaviridae families. In addition, a new genotype of rodent Hepacivirus was identified in heart and lung homogenates of seven viscera pools and phylogenetic analysis revealed the closest relationship to rodent Hepacivirus isolate RtMm-HCV/IM2014 that was previously reported to infect rodents from Inner Mongolia, China. Moreover, nine new genotype viral sequences that corresponded to Picobirnaviruses (PBVs), which have a bi-segmented genome and belong to the family Picobirnaviridae, comprising of three segment I and six segment II sequences, were identified in intestines and liver of seven viscera pools. In the two phylogenetic trees that were constructed using ORF1 and ORF2 of segment I, the three segment I sequences were clustered into distinct clades. Additionally, phylogenetic analysis showed that PBV sequences were distributed in the whole tree that was constructed using the RNA-dependent RNA polymerase (RdRp) gene of segment II with high diversity, sharing 68.42–82.67% nucleotide identities with other genogroup I and genogroup II PBV strains based on the partial RdRp gene. By RNA sequencing, we found a high degree of biodiversity of Retro-, Flavi-, Pneumo-, and Picobirnaridae families and other zoonotic viruses in gerbils, indicating that zoonotic viruses are a common presence in gerbils from Xinjiang, China. Therefore, further research is needed to determine the zoonotic potential of these viruses that are carried by other rodent species from different ecosystems and wildlife in general.

High detection rates and genetic diversity of picobirnaviruses (PBVs) in pigs on St. Kitts Island: Identification of a porcine PBV strain closely related to simian and human PBVs

We report here high rates (75.38%, 49/65) of detection of genogroup I (GI) PBVs in diarrheic pigs on the Caribbean island of St. Kitts. High quality gene segment-2 sequences encoding a significant region (~350 amino acid (aa) residues) of the putative RNA-dependent RNA polymerase (RdRp) were obtained for 23 PBV strains. The porcine PBV strains from St. Kitts exhibited high genetic diversity among themselves (deduced aa identities of 56–100%) and with other PBVs (maximum deduced aa identities of 64–97%), and retained the three domains that are conserved in putative RdRps of PBVs. The nearly complete gene segment-2 sequence (full-length minus partial 3′- untranslated region) of a porcine PBV strain (strain PO36 from St. Kitts) that is closely related (deduced aa identities of 96–97%) to simian and human GI PBVs was determined using a combination of the non-specific primer-based amplification method and conventional RT-PCR. The complete putative RdRp sequence of strain PO36 preserved the various features that are maintained in PBVs from various species. For the first time, several co-circulating PBV strains from pigs were characterized for a significant region (~350 aa) of the putative RdRp, providing important insights into the genetic diversity of PBVs in a porcine population. Taken together, these observations corroborated growing evidence that PBVs can be highly prevalent and show limited correlation globally with host species or geography. This is the first report on detection of PBVs in pigs from the Caribbean region.

Detection and Molecular Characterization of Picobirnaviruses (PBVs) in the Mongoose: Identification of a Novel PBV Using an Alternative Genetic Code.

We report high rates of detection (35.36%, 29/82) of genogroup-I (GI) picobirnaviruses (PBVs) in non-diarrheic fecal samples from the small Indian mongoose (Urva auropunctata). In addition, we identified a novel PBV-like RNA-dependent RNA polymerase (RdRp) gene sequence that uses an alternative mitochondrial genetic code (that of mold or invertebrate) for translation. The complete/nearly complete gene segment-2/RdRp gene sequences of seven mongoose PBV GI strains and the novel PBV-like strain were obtained by combining a modified non-specific primer-based amplification method with conventional RT-PCRs, facilitated by the inclusion of a new primer targeting the 3′-untranslated region (UTR) of PBV gene segment-2. The mongoose PBV and PBV-like strains retained the various features that are conserved in gene segment-2/RdRps of other PBVs. However, high genetic diversity was observed among the mongoose PBVs within and between host species. This is the first report on detection of PBVs in the mongoose. Molecular characterization of the PBV and PBV-like strains from a new animal species provided important insights into the various features and complex diversity of PBV gene segment-2/putative RdRps. The presence of the prokaryotic ribosomal binding site in the mongoose PBV genomes, and analysis of the novel PBV-like RdRp gene sequence that uses an alternative mitochondrial genetic code (especially that of mold) for translation corroborated recent speculations that PBVs may actually infect prokaryotic or fungal host cells.

Molecular Detection and Characterization of Picobirnavirus in Environmental Water in Thailand.

Enteric viruses are responsible for waterborne and foodborne infections affecting a large number of people around the world. Picobirnavirus (PBV) is a highly versatile virus, detected in a wide range of hosts and has been reported to be associated with gastroenteritis in humans and animals. Molecular screening of environmental water samples for PBV was performed over a period of two years from November 2016 to July 2018. The virus was detected by RT multiplex-PCR, nucleotide sequencing, and phylogenetic analysis. Out of 125 water samples, 1.6% (2 samples) tested positive for PBV. Nucleotide sequence analysis showed that both PBV strains detected in this study belonged to PBV genotype II and most closely related to the human PBV genotype II reference strains previously detected in China, the Netherlands, and the USA. This study reports the first detection of PBV genotype II in environmental water in Thailand. Our result highlights the need for better sanitation and disposal of waste water within this area.

High detection rate and high genetic diversity of genogroup I Picobirnaviruses from roe deer

Picobirnaviruses (PBVs) have been characterized as opportunistic enteric pathogens detected in various domestic, zoo and wild animals, suggesting a wide host range of these viruses. It is thus important to monitor wild animals for the presence of various human and animal pathogens in order to identify a potential reservoir of infectious diseases. In this study, the first phylogenetic analysis of PBV from roe deer (Capreolus capreolus) was performed with a total of 70 investigated samples of feces from roe deer collected in 2014 and 2015 during a survey throughout Slovenia. A high detection rate of PBVs was observed with newly designed specific primers, 42 samples out of 70 (60%) being positive. Phylogenetic analysis of the partial RdRp gene showed that roe deer PBV sequences were distributed over the whole phylogenetic tree and were distributed between 7 highly supported groups and 12 separate branches within the PBV genogroup I. The animal PBV strain most closely related to roe deer PBV strains was the Rhesus macaque PBV/BGD/PbV-55 strain, with 89.1% nucleotide identity to that of PBV SLO/D80-14. Overall nucleotide sequence identity between PBV strains obtained from roe deer ranged from 60.4 to 100%, confirming the high genetic diversity with no subtypes related to host species or geographic location in general. This first phylogenetic survey of roe deer PBVs provides further knowledge concerning the putative host range and confirms the high genetic diversity of these PBVs.

Molecular characterization of a novel picobirnavirus in a chicken.

Picobirnaviruses (PBVs) are bisegmented viruses with a wide geographical and host species distribution. The number of novel PBV sequences has been increasing with the help of the viral metagenomics. A novel picobirnavirus strain, pbv/CHK/M3841/HUN/2011, was identified by viral metagenomics; the complete segment 1 (MH327933) and 2 (MH327934) sequences were obtained by RT-PCR from a cloacal sample of a diseased broiler breeder pullet in Hungary. Although the conserved nucleotide (e.g., ribosome binding site) and amino acid motifs (e.g., ExxRxNxxxE, S-domain of the viral capsid and motifs in the RNA-dependent RNA polymerase) were identifiable in the chicken picobirnavirus genome, the putative segment 1 showed low (<30%) amino acid sequence identity to the corresponding proteins of marmot and dromedary PBVs, while segment 2 showed higher (<70%) amino acid sequence identity to a wolf PBV protein sequence. This is the first full-genome picobirnavirus sequence from a broiler breeder chicken, but the pathogenicity of this virus is still questionable.

High detection rates of picobirnaviruses in free roaming rats (Rattus spp.): Molecular characterization of complete gene segment-2

We report here high rates of detection (54%, 21/39) of picobirnaviruses (PBVs) in feces/intestinal contents of free roaming, apparently healthy rats (Rattus spp.) on the Caribbean island of St. Kitts. One of the PBV strains, strain PBV/Rat/KNA/Rat9/2017, was molecularly characterized for complete gene segment-2. To determine the nucleotide (nt) sequence of full-length gene segment-2, the 5′- and 3′- portions of gene segment-2 of strain Rat9 containing an overlapping region were amplified using a non-specific primer-based amplification method with modifications. The complete gene segment-2 of PBV strain Rat9 was 1730 bp in length, encoding a putative RNA-dependent RNA polymerase (RdRp) of 535 amino acid (aa). By nt and deduced aa sequence identities and phylogenetic analysis, the complete gene segment-2 of strain Rat9 exhibited high genetic diversity with those of PBVs from other host species. On the other hand, 5′- and 3′- end nt sequences of gene segment-2, and the three domains of putative RdRp that are conserved in PBVs were retained in strain Rat9. To our knowledge, this is the first report on molecular characterization of complete gene segment-2 of a PBV strain from Rattus spp., providing important insights into the putative RdRp, and genetic diversity and evolution of PBV in rats. The high detection rates of PBV in free roaming rats on St. Kitts emphasizes the importance of further studies on epidemiology and genetic makeup of PBVs in Rattus spp.

Molecular epidemiology and characterization of picobirnaviruses in small ruminant populations in India

Picobirnavirus (PBV) is recognized as a putative cause of diarrhea and respiratory illnesses. Although PBV has been reported in several mammalian (including humans) and avian host species, data pertaining to its presence in small ruminants are limited. We report, here, PBV infection in small ruminants (ovine and caprine), in India. From January 2015 to December 2017, 400 samples were tested for the presence of PBV, using an RT-PCR assay specific for the genome segment-2. The overall rate of PBV infection was 35.75% (143/400), being higher in caprines (42.35%, 83/196) than in ovines (29.42%, 60/204). Viral genogrouping showed the predominance of PBV genogroup I (GG-I; 53.15%, 76/173), the detection of genogroup II (GG-II; 3.49%, 5/143), a concomitant infection with GG-I and GG-II (38.47%, 55/143), and un-typeable strains (4.9%, 7/143). Of note, these PBV strains exhibit low sequence identity (11.2% to 70.7%) to other reported PBV isolates from humans and other animals. By phylogenetic analysis, camel PBV isolates from the United Arab Emirates (UAE) and the reference human GG-I strain (1-CHN-97) from China were found to be the nearest neighbors of PBV strains. Furthermore, sequence analysis revealed the possible appearance of a new genogroup/genetic cluster and the existence of high genetic heterogeneity in the circulating PBV strains. Although much remains to be understood about the epidemiology and impact of PBV, the present study demonstrates the high prevalence of GG-I, the detection of GG-II, and the possible emergence of new genogroup/genetic cluster in small ruminant populations in India.

Molecular characterization of complete genomic segment-2 of picobirnavirus strains detected in a cat and a dog

We report here molecular characterization of complete genomic segment-2 of picobirnavirus (PBV) strains PBV/Cat/KNA/K40/2014 and PBV/Dog/KNA/RVC7/2015 detected in a cat (Felis catus) and a dog (Canis lupus familiaris), respectively, on the Caribbean island of St. Kitts. To obtain the full-length nucleotide (nt) sequence of gene segment-2 of the canine and feline PBV strains, the 5′- and 3′- portions of gene segment-2 containing an overlapping region were amplified using a non-specific primer-based amplification method with modifications. The complete gene segment-2 of feline PBV strain K40 and canine PBV strain RVC7 was 1784nt and 1689nt long, respectively, and encoded a putative RNA-dependent RNA polymerase (RdRp) of 534 amino acid (aa) and 531 aa, respectively. The complete gene segment-2 of strains K40 and RVC7 exhibited a high degree of genetic diversity between themselves, and with those of PBVs from other host species. On the other hand, both the canine and feline PBV strains retained the 5′- and 3′- end nucleotide sequences and the three domains of putative RdRp that are conserved in PBVs. To our knowledge, this is the first report on molecular characterization of complete gene segment-2 of PBV strains detected in cats and dogs, allowing us to study the features of putative RdRps of PBVs in these host species, and providing important insights into the genetic makeup and evolution of feline and canine PBV strains. PBVs were detected for the first time in cats and dogs from the Caribbean region.

Detection of picobirnaviruses in vervet monkeys (Chlorocebus sabaeus): Molecular characterization of complete genomic segment-2

During 2014–2015, 270 fecal samples were collected from non-diarrheic, captive and wild African green monkeys (AGMs) on the island of St. Kitts, Caribbean region. By RNA-PAGE, picobirnaviruses (PBVs) were detected in sixteen captive AGMs. By RT-PCR and sequencing of partial gene segment-2, PBVs in 15 of these 16 samples were assigned to genogroup-I. The full-length nucleotide (nt) sequence of gene segment-2 of one of the genogroup-I PBV strains, strain PBV/African green monkey/KNA/016593/2015, was obtained using a non-specific primer-based amplification method with modifications. Gene segment-2 of strain 016593 was 1707bp long, and encoded a putative RNA-dependent RNA polymerase (RdRp) of 538aa. Furthermore, the nearly complete gene segment-2 sequences of three other AGM PBV strains were determined using primers designed from gene segment-2 sequence of 016593. The gene segment-2 of the 4 AGM PBV strains were almost identical to each other, and exhibited a high degree of genetic diversity (maximum nt and deduced aa sequence identities of 66.4% and 65.3%, respectively) with those of PBVs from other host species. The 5′- and 3′- (except for one mismatch) end nt sequences and the three domains of RdRps were retained in the AGM PBV strains. To our knowledge, this is the first report on detection, and molecular characterization of complete gene segment-2 of PBVs in vervet monkeys. PBVs were detected for the first time from the Caribbean region.

Molecular detection and characterization of picobirnaviruses in piglets with diarrhea in Thailand.

Picobirnavirus (PBV) is a small, bi-segmented, double-stranded RNA virus. Taxonomically, the genus Picobirnavirus belongs to the Picobirnaviridae family. PBV infects a wide range of hosts and causes opportunistic infections, but its role in diarrheal disease remains unclear. To determine the prevalence and genetic diversity of porcine PBVs in Northern Thailand, 380 fecal samples collected from diarrheic and non-diarrheic piglets, raised in 22 pig farms, were tested for the presence of PBV. Reverse-transcription PCR (RT-PCR) was performed using primer sets specific to the RNA-dependent RNA polymerase (RdRp) gene. PBV was detected in 86 of 265 (32.5%) diarrheic piglets and in 26 of 115 (22.6%) non-diarrheic piglets. All the PBV strains detected in this study belonged to genogroup I and a high proportion of PBV-positive piglets were co-infected with group A rotavirus (RVA) and bocavirus (BoV). Phylogenetic analysis of representative genogroup I strains revealed remarkably high similarity between strains; these formed a monophyletic cluster with 97-100% sequence identity in the RdRp gene. The strains were also closely related to genogroup I PBV Chinese porcine strain. The findings indicate that PBV infection is common in piglets with and without diarrhea in Northern Thailand.

High Diversity of Genogroup I Picobirnaviruses in Mammals.

In a molecular epidemiology study using 791 fecal samples collected from different terrestrial and marine mammals in Hong Kong, genogroup I picobirnaviruses (PBVs) were positive by RT-PCR targeting the partial RdRp gene in specimens from five cattle, six monkeys, 17 horses, nine pigs, one rabbit, one dog, and 12 California sea lions, with 11, 9, 23, 17, 1, 1, and 15 sequence types in the positive specimens from the corresponding animals, respectively. Phylogenetic analysis showed that the PBV sequences from each kind of animal were widely distributed in the whole tree with high diversity, sharing 47.4–89.0% nucleotide identities with other genogroup I PBV strains based on the partial RdRp gene. Nine complete segment 1 (viral loads 1.7 × 104 to 5.9 × 106/ml) and 15 segment 2 (viral loads 4.1 × 103 to 1.3 × 106/ml) of otarine PBVs from fecal samples serially collected from California sea lions were sequenced. In the two phylogenetic trees constructed using ORF2 and ORF3 of segment 1, the nine segment 1 sequences were clustered into four distinct clades (C1–C4). In the tree constructed using RdRp gene of segment 2, the 15 segment 2 sequences were clustered into nine distinct clades (R1–R9). In four sea lions, PBVs were detected in two different years, with the same segment 1 clade (C3) present in two consecutive years from one sea lion and different clades present in different years from three sea lions. A high diversity of PBVs was observed in a variety of terrestrial and marine mammals. Multiple sequence types with significant differences, representing multiple strains of PBV, were present in the majority of PBV-positive samples from different kinds of animals.

Electrophoretic RNA genomic profiles of Brazilian Picobirnavirus (PBV) strains and molecular characterization of a PBV isolated from diarrheic calf

Picobirnavirus (PBV) belongs to the family Picobirnaviridae. PBV are a group of emerging non-enveloped viruses, with a bisegmented double-stranded RNA genome that can infect a wide range of hosts. This study reports the occurrence of PBV in fecal samples from five Brazilian dairy cattle herds. From the 289 stool samples of individual calves analyzed by silver-stained polyacrylamide gel electrophoresis (ss-PAGE) the PBV was detected in 8.3 % (24/289), of which 10.2% (18/176) had diarrheic consistency. Of the 24 positive samples in ss-PAGE, 5 (20.8%) of them showed a small electrophoretic profile and 19 (79.2%) samples had large profile. From the 24 positives samples by ss-PAGE, 15 (62.5%) were successfully amplified (201bp) using GI specific primers targeting the RdRp gene of PBV. The analysis of nucleotide identity matrix revealed that the bovine PBV strain identified in this study, showed the highest nucleotide identity (81%) with PBV strain detected in turkey (MD-2010/HM803965). This is the first nucleotide sequence of a bovine PBV strain in the American continent and the first detection of small genome profile of PBV-like strains in bovine hosts.

Prevalence and complete genome characterization of turkey picobirnaviruses

The “light turkey syndrome” (LTS), in which birds weigh less than their standard breed character at the marketing time, is believed to be a consequence of viral enteritis at an early age (3–5weeks) from which the birds never fully recover. In a previously published study, we collected fecal pools from 2, 3, 5 and 8week old turkey poults (80 pools from LTS farms and 40 from non-LTS farms) and examined them for the presence of astro-, rota-, reo-, and coronaviruses. To determine the presence of additional enteric viruses, we analyzed a fecal pool by Illumina sequencing and found picobirnavirus (PBV). Segments 1 and 2 of this virus shared 45.8%aa and 60.9–64.5%aa identity with genogroup I of human PBV, respectively. Primers based on RNA-dependent RNA polymerase and capsid genes were designed for detection and molecular characterization of PBVs in the 120 fecal pools described above. From LTS farms, 39 of 80 (48.8%) pools were PBV positive while 23 of 40 (57.5%) were positive from non-LTS farms. The phylogenetic analysis of 15 randomly selected strains divided them into four subgroups within genogroup I (subgroups 1A–D). Nine strains were in subgroup IA showing 69.9–76.4%nt identity with human PBV GI strainVS111 from the Netherlands. Strains in subgroup IB (n=2) had 91.4–91.7%nt identity with chicken PBV GI strain AVE 42v1 from Brazil. Two strains in subgroup IC had 72.3–74.2%nt identity with chicken PBV strain AVE 71v3 from Brazil. In subgroup ID, two strains showed 72.4–81.8%nt identity with chicken PBV GI strain AVE 57v2 from Brazil. Subgroup IC and ID were the most divergent. Five of the 15 strains were typed using capsid gene primers. They showed 32.6–33.4%nt and 39.5–41.3%aa identity with VS10 human PBV strain. These results indicate co-circulation of divergent strains of PBVs among Minnesota turkeys.

Maintenance of picobirnavirus (PBV) infection in an adult orangutan (Pongo pygmaeus) and genetic diversity of excreted viral strains during a three-year period

The present work provide data about the maintenance of picobirnavirus (PBV) infection during adulthood in a mammalian host. For this purpose PBV infection was studied in an adult orangutan (Pongo pygmaeus) by PAGE/SS, RT-PCR and nucleotide sequencing. PBV infection in the animal was asymptomatic and was characterized by interspaced silent and high/ low active viral excretion periods. The PBV strains excreted by the studied individual were identified as genogroup I and revealed a nucleotide identity among them of 64–81%.The results obtained allowed to arrive to a deeper understanding of the natural history of PBV infection, which seems to be characterized by new-born, juvenile and adult asymptomatic hosts which persistently excrete closely related strains in their feces. Consequently, picobirnaviruses could be considered frequent inhabitants of the gastrointestinal tract, leaving the question open about the molecular mechanisms governing persistent and asymptomatic coexistence within the host and the potential host suitability to maintain this relationship.

Establishment and maintenance of persistent infection by picobirnavirus in greater rhea (Rhea Americana)

A study aimed to determine the infection model that picobirnavirus (PBV) established in birds was conducted in a farm of greater rheas in Córdoba, Argentina. Analysis of stools collected during a longitudinal study involving seven birds provided evidence that PBV is acquired very early in life and establishes a persistent infection in the host, which is characterized by intermingled periods of high, low and silent viral activity. Genomic analysis indicated that the rheas excreted virus with nucleotide sequence identity between 90.5-100% and that more than one PBV strain with different electropherotype profiles could be involve in the infection. This report provides the first evidence of persistent infection of PBV in birds. The natural history of PBV infection has begun to be understood, and it appears that asymptomatic PBV-infected mammals and birds could persistently excrete the virus in stool samples, contributing to wide circulation of the virus in the environment.

Simian Genogroup I Picobirnaviruses: Prevalence, Genetic Diversity, and Zoonotic Potential

We previously reported the first detection of simian picobirnaviruses (PBVs) by polyacrylamide gel electrophoresis in fecal specimens of two monkeys with diarrhea in China. We now report the detection of genogroup I PBVs in 48% (44/92) of the fecal specimens by reverse transcriptase PCR (RT-PCR) and amplicon sequencing using primers specific for the RNA-dependent RNA polymerase (RDRP) gene. Molecular characterization of these 44 strains demonstrated both sequence conservation and diversity among simian PBVs and among simian, porcine, and human PBVs. We further determined full-length sequences of segment 2 of the two simian PBV strains, monkey/CHN-14/2002 and monkey/CHN-49/2002, and demonstrated 52.5% to 54.2% nucleotide sequence similarity to the corresponding gene of the bovine strain RUBV and the prototype human strain 1-CHN-97 of genogroup I PBVs and an even lower similarity (38.4%) to segment 2 of the prototype human genogroup II strain 4-GA-91. Further studies are needed to investigate the epidemiology and pathogenesis of PBVs in animals and humans.

Picobirnavirus infections: viral persistence and zoonotic potential

Picobirnaviruses (PBVs) are small, non-enveloped, bisegmented double-stranded RNA genomic viruses of vertebrate hosts. Since their discovery in the late 1980s in clinical specimens from outbreaks of acute gastroenteritis in children, significant efforts have been made to investigate the role of PBV in diarrheic diseases. PBV has been detected in sporadic episodes of diarrhea as sole pathogen or coinfection as well as in outbreaks of acute gastroenteritis and in immunocompromised patients with diarrhea. However, PBV is frequently detected in non-diarrheic healthy hosts, and prolonged shedding has been observed in some individuals. Of interest, similar patterns of PBV infection have also been observed in pigs and other animal hosts. The increasing amount of PBV sequence data gathered from molecular epidemiological studies has evidenced a great sequence diversity of PBVs in various hosts and environmental samples. Importantly, evidence has been found for genetic relatedness between human and animal PBV strains, suggesting extant crossing points in the ecology and evolution of heterologous PBV strains. At present, no cell culture and animal model exists for PBVs. Well-structured epidemiological studies are still the only alternative to demonstrate the potential etiological role of PBVs in acute gastroenteritis or other diseases. This review aims to analyze the public health aspects of PBV infection, especially its possible association with zoonosis.

Evidence of closely related picobirnavirus strains circulating in humans and pigs in Argentina

On the basis of the published literature, it is still difficult to draw conclusions as to whether picobirnavirus (PBV) circulation is influenced by host species restriction. To provide data regarding the genetic relatedness between porcine and human PBV strains present in Argentina as a means of defining the host range and epidemiology of these viruses. Fecal specimens (n=74) collected from kidney transplant patients (n=55) and piglets (n=19) were analyzed by RT-PCR using primers designed to amplify the porcine PBV genomic segment 2. Amplified sequences were further examined phylogenetically. By RT-PCR amplification 14 of 74 samples rendered amplicons of the expected 282 base pair size (8 detected from humans and 6 from pigs). Eleven amplicons (5 from humans and 6 from pigs) were selected for sequencing and subjected to phylogenetic analysis. The eleven amplicons revealed similarities between human and porcine viral sequences that ranged between 94.7 and 100% in identity. Phylogenetic analysis identified these 11 strains as PBV genogroup I-related strains and showed that they grouped as a single separate clade distinct from other PBV strains detected in humans and porcine from other countries. The present study suggests that closely related PBV strains infect both pigs and humans in Argentina and that the epidemiology of PBVs is not species restricted.