Current Insights into Porcine Bocavirus (PBoV) and Its Impact on the Economy and Public Health

Effective control of animal infectious diseases is crucial for maintaining robust livestock production systems worldwide. Porcine meat constitutes approximately 35-40% of global meat production with the largest producers being China and the European Union (EU). Emerging viral pathogens in swine, like porcine bocavirus (PBoV), have not garnered significant attention, leaving their pathogenic characteristics largely unexplored. This review aims to bridge this knowledge gap by conducting a comprehensive analysis of the existing literature on PBoV. We explore the virus's genome structure, discovery, classification, detection methods, pathogenesis, and its potential public health implications. Additionally, we discuss the distribution and economic impact of PBoV, which includes potential losses due to decreased productivity, increased veterinary costs, and trade restrictions. By highlighting the current state of knowledge, this review seeks to enhance the understanding of PBoV, thereby aiding in its prevention and control, and mitigating its economic impact on the swine industry.

Development of a Synthetic VP1 Protein Peptide-Based ELISA to Detect Antibodies Against Porcine Bocavirus Group 3

Porcine bocavirus (PBoV), classified within the genus Bocaparvovirus, has been reported worldwide. PBoV has been divided into group 1, group 2, and group 3. PBoV group 3 (G3) viruses are the most prevalent in China. Currently, effective serological methods for the detection of antibodies against PBoV G3 are limited. In this study, we developed an indirect ELISA using a synthetic VP1 peptide designed on the basis of the conserved region of the PBoV VP1 protein as a coating antigen. Through matrix titration, the optimal coating concentration of the VP1 peptide (0.5 μg/mL), serum dilution (1:200), and working concentration of the secondary antibody (1:50,000) were determined. The cutoff value of this developed ELISA was set as 0.4239. Further investigations revealed that this developed ELISA had no cross-reactivity with positive serum antibodies against FMDV-O, FMDV-A, PRV, ASFV, SF, PCV2, PEDV, and TGEV. The detection limit of the method was a 1:1600 dilution of standard positive serum against PBoV G3. The coefficients of variation for both the intra- and interassay data were lower than 10%. A total of 1373 serum samples collected from 12 provinces in China between 2022 and 2023 were subjected to indirect ELISA. The results showed that 47.56% of the samples were PBoV G3 positive. These results reveal that peptide-based ELISA is a reliable and cost-effective method for detecting PBoV G3 antibodies. It also facilitates the investigation of the prevalence and distribution of PBoV G3.

Triplex-Loop-Mediated Isothermal Amplification Combined with a Lateral Flow Immunoassay for the Simultaneous Detection of Three Pathogens of Porcine Viral Diarrhea Syndrome in Swine

Porcine epidemic diarrhea virus (PEDV), porcine bocavirus (PBoV), and porcine rotavirus (PoRV) are associated with porcine viral diarrhea. In this study, triplex loop-mediated isothermal amplification (LAMP) combined with a lateral flow dipstick (LFD) was established for the simultaneous detection of PEDV, PoRV, and PBoV. The PEDV-gp6, PoRV-vp6, and PBoV-vp1 genes were selected to design LAMP primers. The amplification could be carried out at 64 °C using a miniature metal bath within 30 min. The triplex LAMP-LFD assay exhibited no cross-reactions with other porcine pathogens. The limits of detection (LODs) of PEDV, PoRV, and PBoV were 2.40 × 10¹ copies/μL, 2.89 × 10¹ copies/μL, and 2.52 × 10¹ copies/μL, respectively. The consistency between rt-qPCR and the triplex LAMP-LFD was over 99% in field samples testing. In general, the triplex LAMP-LFD assay was suitable for the rapid and simultaneous detection of the three viruses in the field.

Human Bocavirus in Childhood: A True Respiratory Pathogen or a "Passenger" Virus? A Comprehensive Review

Recently, human bocavirus (HBoV) has appeared as an emerging pathogen, with an increasing number of cases reported worldwide. HBoV is mainly associated with upper and lower respiratory tract infections in adults and children. However, its role as a respiratory pathogen is still not fully understood. It has been reported both as a co-infectious agent (predominantly with respiratory syncytial virus, rhinovirus, parainfluenza viruses, and adenovirus), and as an isolated viral pathogen during respiratory tract infections. It has also been found in asymptomatic subjects. The authors review the available literature on the epidemiology of HBoV, the underlying risk factors associated with infection, the virus's transmission, and its pathogenicity as a single pathogen and in co-infections, as well as the current hypothesis about the host's immune response. An update on different HBoV detection methods is provided, including the use of quantitative single or multiplex molecular methods (screening panels) on nasopharyngeal swabs or respiratory secretions, tissue biopsies, serum tests, and metagenomic next-generations sequencing in serum and respiratory secretions. The clinical features of infection, mainly regarding the respiratory tract but also, though rarely, the gastrointestinal one, are extensively described. Furthermore, a specific focus is dedicated to severe HBoV infections requiring hospitalization, oxygen therapy, and/or intensive care in the pediatric age; rare fatal cases have also been reported. Data on tissue viral persistence, reactivation, and reinfection are evaluated. A comparison of the clinical characteristics of single infection and viral or bacterial co-infections with high or low HBoV rates is carried out to establish the real burden of HBoV disease in the pediatric population.

Epidemiologic and clinical characteristics of human bocavirus infection in children hospitalized for acute respiratory tract infection in Qingdao, China

Persistent infection and prolonged shedding of human bocavirus 1 (HBoV1) in children have been reported, and the role of HBoV1 as a sole causative pathogen in acute respiratory infection (ARI) is yet to be established. While the reported prevalence of HBoV infection varies due to different detection methods and sampling criteria, determining the viral and bacterial etiology of HBoV infection using multiplex real-time PCR is yet to be reported. Herein, we aimed to further explore the pathogenicity of HBoV in patients with ARI by screening the viral and bacterial infections in children with ARI in Qingdao and comparing the epidemiological, clinical characteristics, and etiological results. Human bocavirus was identified in 28.1% of the samples, and further sequencing analysis of the detected HBoV confirmed 96.4% as HBoV1. The rate of HBoV as a single viral infection was 75%, and the rate of coinfection with bacteria was 66.1%, suggesting the need for continued monitoring of HBoV in children with ARIs. Clinical characterization suggested that HBoV infection may affect the function of organs, such as the liver, kidney, and heart, and the blood acid–base balance. Additionally, it is essential to promote awareness about the importance of disinfection and sterilization of the hospital environment and standardizing operations. The interactions between HBoV and other pathogens remain to be investigated in further detail in the future.

Small but mighty: old and new parvoviruses of veterinary significance

In line with the Latin expression "sed parva forti" meaning "small but mighty," the family Parvoviridae contains many of the smallest known viruses, some of which result in fatal or debilitating infections. In recent years, advances in metagenomic viral discovery techniques have dramatically increased the identification of novel parvoviruses in both diseased and healthy individuals. While some of these discoveries have solved etiologic mysteries of well-described diseases in animals, many of the newly discovered parvoviruses appear to cause mild or no disease, or disease associations remain to be established. With the increased use of animal parvoviruses as vectors for gene therapy and oncolytic treatments in humans, it becomes all the more important to understand the diversity, pathogenic potential, and evolution of this diverse family of viruses. In this review, we discuss parvoviruses infecting vertebrate animals, with a special focus on pathogens of veterinary significance and viruses discovered within the last four years.

Exploring the Cause of Diarrhoea and Poor Growth in 8-11-Week-Old Pigs from an Australian Pig Herd Using Metagenomic Sequencing

Diarrhoea and poor growth among growing pigs is responsible for significant economic losses in pig herds globally and can have a wide range of possible aetiologies. Next generation sequencing (NGS) technologies are useful for the detection and characterisation of diverse groups of viruses and bacteria and can thereby provide a better understanding of complex interactions among microorganisms potentially causing clinical disease. Here, we used a metagenomics approach to identify and characterise the possible pathogens in colon and lung samples from pigs with diarrhoea and poor growth in an Australian pig herd. We identified and characterized a wide diversity of porcine viruses including RNA viruses, in particular several picornaviruses—porcine sapelovirus (PSV), enterovirus G (EV-G), and porcine teschovirus (PTV), and a porcine astrovirus (PAstV). Single stranded DNA viruses were also detected and included parvoviruses like porcine bocavirus (PBoV) and porcine parvovirus 2 (PPV2), porcine parvovirus 7 (PPV7), porcine bufa virus (PBuV), and porcine adeno-associated virus (AAV). We also detected single stranded circular DNA viruses such as porcine circovirus type 2 (PCV2) at very low abundance and torque teno sus viruses (TTSuVk2a and TTSuVk2b). Some of the viruses detected here may have had an evolutionary past including recombination events, which may be of importance and potential involvement in clinical disease in the pigs. In addition, our metagenomics data found evidence of the presence of the bacteria Lawsonia intracellularis, Brachyspira spp., and Campylobacter spp. that may, together with these viruses, have contributed to the development of clinical disease and poor growth.

Porcine Bocavirus: A 10-Year History since Its Discovery

Porcine bocavirus (PBoV) is a single-stranded DNA virus, belongs to the genus Bocaparvovirus of family Parvoviridae. It was discovered along with porcine circovirus 2 (PCV 2) and torque tenovirus (TTV) in the lymph nodes of pigs suffering from postweaning multisystemic wasting syndrome (PMWS) in Sweden in 2009. PBoV has been reported throughout the world, mostly in weaning piglets, and has a broad range of tissue tropism. Since PBoV is prevalent in healthy as well as clinically infected pigs and is mostly associated with coinfection with other viruses, the pathogenic nature of PBoV is still unclear. Currently, there are no cell lines available for the study of PBoV, and animal model experiments have not been described. This review summarizes the current state of knowledge about PBoV, including the epidemiology, evolution analysis, detection methods, pathogenesis and public health concerns.

Virome characterization in serum of healthy show pigs raised in Oklahoma demonstrated great diversity of ssDNA viruses

In the United States, show pigs are raised to compete in agricultural events. These animals are usually raised in small herds with extensive human, domestic, and wild animal contact. Therefore, pathogen monitoring in this animal category is critical for improved disease surveillance and preparedness. This study characterized the virome of healthy show pigs using high-throughput sequencing using pooled serum samples from 2018 or 2019 (200 samples each pool). Results demonstrated the presence of DNA viral families (Parvoviridae, Circoviridae, and Herpesviridae) and RNA families (Arteriviridae, Flaviviridae, and Retroviridae). Twenty-three viral species were identified, including the first detection of porcine bufavirus in the US. Moreover, important swine pathogens identified included porcine reproductive and respiratory syndrome virus, atypical porcine pestivirus, and porcine circovirus (PCV). Additionally, complete coding genomes of 17 viruses from the Parvoviridae, Anelloviridae, and Circoviridae families were retrieved and included the first near full-length genomes of US Ungulate bocaparvovirus 3 species.

Detection and genetic characteristics of porcine bocavirus in central China

To investigate the epidemic profile and genetic diversity of porcine bocavirus (PBoV), 281 clinical samples, including 236 intestinal tissue samples and 45 fecal samples were collected from diarrheic piglets on 37 different pig farms in central China, and two SYBR Green I-based quantitative PCR assays were developed to detect PBoV1/2 and PBoV3/4/5, respectively. One hundred forty-eight (52.67%) of the 281 clinical samples were positive for PBoV1/2, 117 (41.63%) were positive for PBoV3/4/5, 55 (19.57%) were positive for both PBoV1/2 and PBoV3/4/5, and 86.49% (32/37) of the pig farms were positive for PBoV. Overall, the prevalence of PBoV was 74.73% (210/281) in central China. Subsequently, nearly full-length genomic sequences of two PBoV strains (designated CH/HNZM and PBoV-TY) from two different farms were determined. Phylogenetic analysis demonstrated that the two PBoV strains obtained in this study belonged to the PBoV G2 group and had a close relationship to 10 other PBoV G2 strains but differed genetically from PBoV G1, PBoV G3, and seven other bocaviruses. CH/HNZM and PBoV-TY were closely related to the PBoV strain GD18 (KJ755666), which may be derived from the PBoV strains 0912/2012 (MH558677) and 57AT-HU (KF206160) through recombination. Compared with reference strain ZJD (HM053694)-China, more amino acid variation was found in the NS1 proteins of CH/HNZM and PBoV-TY. These data extend our understanding of the molecular epidemiology and evolution of PBoV.

Development of a duplex SYBR GreenⅠ based real-time PCR assay for detection of porcine epidemic diarrhea virus and porcine bocavirus3/4/5

The duplex real-time PCR assay based on SYBR Green І was developed for detection of porcine epidemic diarrhea virus (PEDV) and porcine bocavirus (PBoV) 3/4/5 genotypes simultaneously. Two pairs of specific primers were designed targeting the N gene sequence of PEDV and VP1 gene sequence of PBoV3/4/5. PEDV and PBoV3/4/5 could be distinguished by their different melting temperatures (Tm) in one sample. The Tm value of PEDV was 83.5 °C, and the Tm value of PBoV3/4/5 was 78.5 °C, while other swine pathogens showed no specific melting peaks. The detection limits of this assay were 10 copies/μL for both PEDV and PBoV3/4/5. A total of sixty-three intestinal tissue samples were collected from piglets suffering from diarrhea, and the viral nucleic acids detected and identified by the real-time PCR assay and conventional PCR assay. The duplex real-time PCR detection results showed that the prevalence of PEDV and PBoV3/4/5 was 85.7% and 46%, respectively, and the co-infection rate of the two viruses was 28.6%. These results indicated that this duplex real-time PCR assay was a sensitive, specific and reproducible method for differentiating PEDV and PBoV3/4/5 or their co-infection.

Sequence and phylogenetic analysis of novel porcine parvovirus 7 isolates from pigs in Guangxi, China

Parvoviruses are a diverse group of viruses that infect a wide range of animals and humans. In recent years, advances in molecular techniques have resulted in the identification of several novel parvoviruses in swine. In this study, porcine parvovirus 7 (PPV7) isolates from clinical samples collected in Guangxi, China, were examined to understand their molecular epidemiology and co-infection with porcine circovirus type 2 (PCV2). In this study, among the 385 pig serum samples, 105 were positive for PPV7, representing a 27.3% positive detection rate. The co-infection rate of PPV7 and PCV2 was 17.4% (67/385). Compared with the reference strains, we noted 93.9%-97.9% similarity in the NS1 gene and 87.4%-95.0% similarity in the cap gene. Interestingly, compared with the reference strains, sixteen of the PPV7 strains in this study contained an additional 3 to 15 nucleotides in the middle of the cap gene. Therefore, the Cap protein of fourteen strains encoded 474 amino acids, and the Cap protein of the other two strains encoded 470 amino acids. However, the Cap protein of the reference strain PPV7 isolate 42 encodes 469 amino acids. This is the first report of sequence variation within the cap gene, confirming an increase in the number of amino acids in the Cap protein of PPV7. Our findings provide new insight into the prevalence of PPV7 in swine in Guangxi, China, as well as sequence data and phylogenetic analysis of these novel PPV7 isolates.

Seroprevalence of porcine bocavirus in pigs in north-central China using a recombinant-NP1-protein-based indirect ELISA

Porcine bocavirus (PBoV), which belongs the genus Bocaparvovirus, has been identified throughout the world. However, serological methods for detecting anti-PBoV antibodies are presently limited. In the present study, an indirect enzyme-linked immunosorbent assay (PBoV-rNP1 ELISA) based on a recombinant form of nucleoprotein 1 (NP1) of PBoV was established for investigating the seroprevalence of PBoV in 2025 serum specimens collected in north-central China from 2016 to 2018, and 42.3% of the samples tested positive for anti-PBoV IgG antibodies, indicating that the seroprevalence of PBoV is high in pig populations in China.

Identification and characterization of a novel rodent bocavirus from different rodent species in China

Members in the genus Bocaparvovirus are closely related to human health and have a wide host range. The diverse hosts raise the possibility of crossing species barrier, which is a feature of emerging viruses. Among the mammalian hosts, rodents are generally acknowledged to be important reservoirs of emerging viruses. Here, rodent samples collected from six provinces and autonomous regions of China (Liaoning, Inner Mongolia, Tibet, Xinjiang, Guangxi and Yunnan) were used to investigate the prevalence and distribution of bocaparvoviruses. By using next-generation sequencing first, a partial non-structural protein 1 (NS1) gene belonging to a possible novel bocaparvovirus was discovered. Following this, PCR-based screening of NS1 gene was conducted in 485 rodent samples, with 106 positive results found in seven rodent species (Rattus norvegicus, Mus musculus, Apodemus agrarius, Cricetulus barabensis, Rattus flavipectus, Rattus rattus and Rhombomys opimus). Finally, six nearly full-length genomes and three complete CDS were obtained and the newly identified bocaparvovirus was tentatively named rodent bocavirus (RoBoV). RoBoV has three ORFs: NS1, NP1, and VP, which are characteristics of bocaparvoviruses. Phylogenetic analyses revealed that porcine bocavirus isolate PBoV-KU14, a member of Ungulate bocaparvovirus 4, was the most related virus to RoBoV, with 92.1-92.9% amino acid identities in NS1 protein. Alignments of RoBoV-related sequences showed RoBoV isolates could be classified into two clades, demonstrating an inter-host genetic diversity. The results indicate a potential interspecies transmission of RoBoV between rodents and swine and expand our knowledge on bocaparvoviruses in rodent populations.

First molecular detection of porcine bocavirus in Malaysia

Several strains of porcine bocaviruses have been reported worldwide since their first detection in Sweden in 2009. Subsequently, the virus has been reported to be associated with gastrointestinal and respiratory signs in weaner and grower pigs. Although Malaysia is host to a self-sufficient swine livestock industry, there is no study that describes porcine bocavirus in the country. This report is the first to describe porcine bocavirus (PBoV) in Malaysian swine herds. PBoV was identified in various tissues from sick and runt pigs using the conventional PCR method with primers targeting conserved regions encoding for the nonstructural protein (NS1) gene. Out of 103 samples tested from 17 pigs, 32 samples from 15 pigs were positive for porcine bocavirus. In addition, a higher detection rate was identified from mesenteric lymph nodes (52.9%), followed by tonsil (37.0%), and lungs (33.3%). Pairwise comparison and phylogenetic analyses based on a 658-bp fragment of NS1 gene revealed that the Malaysian PBoV strains are highly similar to PBoV3 isolated in Minnesota, USA. The presence of porcine bocavirus in Malaysia and their phylogenetic bond was marked for the first time by this study. Further studies will establish the molecular epidemiology of PBoV in Malaysia and clarify pathogenicity of the local isolates.

Two novel bocaparvovirus species identified in wild Himalayan marmots

Bocaparvovirus (BOV) is a genetically diverse group of DNA viruses and a possible cause of respiratory, enteric, and neurological diseases in humans and animals. Here, two highly divergent BOVs (tentatively named as Himalayan marmot BOV, HMBOV1 and HMBOV2) were identified in the livers and feces of wild Himalayan marmots in China, by viral metagenomic analysis. Five of 300 liver samples from Himalayan marmots were positive for HMBOV1 and five of 99 fecal samples from these animals for HMBOV2. Their nearly complete genome sequences are 4,672 and 4,887 nucleotides long, respectively, with a standard genomic organization and containing protein-coding motifs typical for BOVs. Based on their NS1, NP1, and VP1, HMBOV1 and HMBOV2 are most closely related to porcine BOV SX/1-2 (approximately 77.0%/50.0%, 50.0%/53.0%, and 79.0%/54.0% amino acid identity, respectively). Phylogenetic analysis of these three proteins showed that HMBOV1 and HMBOV2 formed two distinctly independent branches in BOVs. According to these results, HMBOV1 and HMBOV2 are two different novel species in the Bocaparvovirus genus. Their identification expands our knowledge of the genetic diversity and evolution of BOVs. Further studies are needed to investigate their potential pathogenicity and their impact on Himalayan marmots and humans.

Two novel dromedary camel bocaparvoviruses from dromedaries in the Middle East with unique genomic features

The recent emergence of Middle East respiratory syndrome (MERS) coronavirus and its discovery from dromedary camels has boosted interest in the search for novel viruses in dromedaries. While bocaparvoviruses are known to infect various animals, it was not known that they exist in dromedaries. In this study, we describe the discovery of two novel dromedary camel bocaparvoviruses (DBoVs), DBoV1 and DBoV2, from dromedary faecal samples in Dubai. Among 667 adult dromedaries and 72 dromedary calves, 13.9 % of adult dromedaries and 33.3 % of dromedary calves were positive for DBoV1, while 7.0 % of adult dromedaries and 25.0 % of dromedary calves were positive for DBoV2, as determined by PCR. Sequencing of 21 DBoV1 and 18 DBoV2 genomes and phylogenetic analysis showed that DBoV1 and DBoV2 formed two distinct clusters, with only 32.6-36.3 % amino acid identities between the DBoV1 and DBoV2 strains. Quasispecies were detected in both DBoVs. The amino acid sequences of the NS1 proteins of all the DBoV1 and DBoV2 strains showed <85 % identity to those of all the other bocaparvoviruses, indicating that DBoV1 and DBoV2 are two bocaparvovirus species according to the ICTV criteria. Although the typical genome structure of NS1-NP1-VP1/VP2 was observed in DBoV1 and DBoV2, no phospholipase A2 motif and associated calcium binding site were observed in the predicted VP1 sequences for any of the 18 sequenced DBoV2, and no start codons were found for their VP1. For all 18 DBoV2 genomes, an AT-rich region of variable length and composition was present downstream to NP1. Further studies will be crucial to understand the pathogenic potential of DBoVs in this unique group of animals.

Viral Metagenomic Analysis Displays the Co-Infection Situation in Healthy and PMWS Affected Pigs

The development of high-throughput sequencing technologies have allowed the possibility to investigate and characterise the entire microbiome of individuals, providing better insight to the complex interaction between different microorganisms. This will help to understand how the microbiome influence the susceptibility of secondary agents and development of disease. We have applied viral metagenomics to investigate the virome of lymph nodes from Swedish pigs suffering from the multifactorial disease postweaning multisystemic wasting syndrome (PMWS) as well as from healthy pigs. The aim is to increase knowledge of potential viruses, apart from porcine circovirus type 2 (PCV2), involved in PMWS development as well as to increase knowledge on the virome of healthy individuals. In healthy individuals, a diverse viral flora was seen with several different viruses present simultaneously. The majority of the identified viruses were small linear and circular DNA viruses, such as different circoviruses, anelloviruses and bocaviruses. In the pigs suffering from PMWS, PCV2 sequences were, as expected, detected to a high extent but other viruses were also identified in the background of PCV2. Apart from DNA viruses also RNA viruses were identified, among them were a porcine pestivirus showing high similarity to a recently (in 2015) discovered atypical porcine pestivirus in the US. Majority of the viruses identified in the background of PCV2 in PMWS pigs could also be identified in the healthy pigs. PCV2 sequences were also identified in the healthy pigs but to a much lower extent than in PMWS affected pigs. Although the method used here is not quantitative the very clear difference in amount of PCV2 sequences in PMWS affected pigs and healthy pigs most likely reflect the very strong replication of PCV2 known to be a hallmark of PMWS. Taken together, these findings illustrate that pigs appear to have a considerable viral flora consisting to a large extent of small single-stranded and circular DNA viruses. Future research on these types of viruses will help to better understand the role that these ubiquitous viruses may have on health and disease of pigs. We also demonstrate for the first time, in Europe, the presence of a novel porcine pestivirus.

Identification and genomic characterization of a novel rat bocavirus from brown rats in China

Despite recent discoveries of novel animal bocaparvoviruses, current understandings on the diversity and evolution of bocaparvoviruses are still limited. We report the identification and genome characterization of a novel bocaparvovirus, rat bocaparvovirus (RBoV), in brown rats (Rattus norvegicus) in China. RBoV was detected in 11.5%, 2.4%, 16.2% and 0.3% of alimentary, respiratory, spleen and kidney samples respectively, of 636 brown rats by PCR, but not in samples of other rodent species, suggesting that brown rats are the primary reservoir of RBoV. Six RBoV genomes sequenced from three brown rats revealed the presence of three ORFs, characteristic of bocaparvoviruses. Phylogenetic analysis showed that RBoV was distantly related to other bocaparvoviruses, forming a distinct cluster within the genus, with ≤55.5% nucleotide identities to the genome of ungulate bocaparvovirus 3, supporting its classification as a novel bocaparvovirus species. RBoV possessed a putative second exon encoding the C-terminal region of NS1 and conserved RNA splicing signals, similar to human bocaparvoviruses and canine bocaparvovirus. In contrast to human, feline and canine bocaparvoviruses which demonstrates inter/intra-host viral diversity, partial VP1/VP2 sequences of 49 RBoV strains demonstrated little inter-host genetic diversity, suggesting a single genetic group. Although the pathogenicity of RBoV remains to be determined, its presence in different host tissues suggests wide tissue tropism. RBoV represents the first bocaparvovirus in rodents with genome sequenced, which extends our knowledge on the host range of bocaparvoviruses. Further studies are required to better understand the epidemiology, genetic diversity and pathogenicity of bocaparvoviruses in different rodent populations.

Identification and interspecies transmission of a novel bocaparvovirus among different bat species in China

We report the discovery of a novel bocaparvovirus, bat bocaparvovirus (BtBoV), in one spleen, four respiratory and 61 alimentary samples from bats of six different species belonging to three families, Hipposideridae, Rhinolophidae and Vespertilionidae. BtBoV showed a higher detection rate in alimentary samples of Rhinolophus sinicus (5.7 %) than those of other bat species (0.43-1.59 %), supporting R. sinicus as the primary reservoir and virus spillover to accidental bat species. BtBoV peaked during the lactating season of R. sinicus, and it was more frequently detected among female than male adult bats (P<0.05), and among lactating than non-lactating female bats (P<0.0001). Positive BtBoV detection was associated with lower body weight in lactating bats (P<0.05). Ten nearly complete BtBoV genomes from three bat species revealed a unique large ORF1 spanning NS1 and NP1 in eight genomes and conserved splicing signals leading to multiple proteins, as well as a unique substitution in the conserved replication initiator motif within NS1. BtBoV was phylogenetically distantly related to known bocaparvoviruses with ≤57.3 % genome identities, supporting BtBoV as a novel species. Ms-BtBoV from Miniopterus schreibersii and Hp-BtBoV from Hipposideros pomona demonstrated 97.2-99.9 % genome identities with Rs-BtBoVs from R. sinicus, supporting infection of different bat species by a single BtBoV species. Rs-BtBoV_str15 represents the first bat parvovirus genome with non-coding regions sequenced, which suggested the presence of head-to-tail genomic concatamers or episomal forms of the genome. This study represents the first to describe interspecies transmission in BoVs. The high detection rates in lactating female and juvenile bats suggest possible vertical transmission of BtBoV.

Development and validation of a multiplex conventional PCR assay for simultaneous detection and grouping of porcine bocaviruses

Porcine bocavirus (PBoV), a newly described porcine parvovirus, has received attention because it can be commonly identified in clinically affected pigs including pigs with post-weaning multisystemic wasting syndrome (PWMS) and pigs with diarrhea. In recent years, novel PBoVs have been identified and were classified into three genogroups, but the ability to detect and classify these novel PBoVs is not comprehensive to date. In this study, a multiplex conventional PCR assay for simultaneous detection and grouping of PBoVs was developed by screening combinations of mixed primer pairs followed by optimization of the PCR conditions. This method exclusively amplifies targeted fragments of 531bp from the VP1 gene of PBoV G1, 291bp from the NP1 gene of PBoV G2, and 384bp from the NP1/VP1 gene of PBoV G3. The assay has a detection limit of 1.0×10(3)copies/μL for PBoV G1 4.5×10(3) for PBoV G2 and 3.8×10(3) for PBoV G3 based on testing mixed purified plasmid constructs containing the specific viral target fragments. The performance of the multiplex PCR assay was comparable to that of the single PCRs which used the same primer pairs. Using the newly established multiplex PCR assay, 227 field samples including faeces, serum and tissue samples from pigs were investigated. All three PBoV genogroups were detected in the clinical samples with a detection rate of 1.3%, 2.6% and 12.3%, respectively for PBoV G1, G2 and G3. Additionally, coinfections with two or more PBoV were detected in 1.7% of the samples investigated. These results indicate the multiplex PCR assay is specific, sensitive and rapid, and can be used for the detection and differentiation of single and multiple infections of the three PBoV genogroups in pigs.

Rapid detection and grouping of porcine bocaviruses by an EvaGreen(®) based multiplex real-time PCR assay using melting curve analysis

Several novel porcine bocaviruses (PBoVs) have been identified in pigs in recent years and association of these viruses with respiratory signs or diarrhea has been suggested. In this study, an EvaGreen(®)-based multiplex real-time PCR (EG-mPCR) with melting curve analysis was developed for simultaneous detection and grouping of novel PBoVs into the same genogroups G1, G2 and G3. Each target produced a specific amplicon with a melting peak of 81.3 ± 0.34 °C for PBoV G1, 78.2 ± 0.37 °C for PBoV G2, and 85.0 ± 0.29 °C for PBoV G3. Non-specific reactions were not observed when other pig viruses were used to assess the EG-mPCR assay. The sensitivity of the EG-mPCR assay using purified plasmid constructs containing the specific viral target fragments was 100 copies for PBoV G1, 50 for PBoV G2 and 100 for PBoV G3. The assay is able to detect and distinguish three PBoV groups with intra-assay and inter-assay variations ranging from 0.13 to 1.59%. The newly established EG-mPCR assay was validated with 227 field samples from pigs. PBoV G1, G2 and G3 was detected in 15.0%, 25.1% and 41.9% of the investigated samples and coinfections of two or three PBoV groups were also detected in 25.1% of the cases, indicating that all PBoV groups are prevalent in Chinese pigs. The agreement of the EG-mPCR assay with an EvaGreen-based singleplex real-time PCR (EG-sPCR) assay was 99.1%. This EG-mPCR will serve as a rapid, sensitive, reliable and cost effective alternative for routine surveillance testing of multiple PBoVs in pigs and will enhance our understanding of the epidemiological features and possible also pathogenetic changes associated with these viruses in pigs.

Metagenomic analysis demonstrates the diversity of the fecal virome in asymptomatic pigs in East Africa

Pigs harbor a variety of viruses that are closely related to human viruses and are suspected to have zoonotic potential. Little is known about the presence of viruses in smallholder farms where pigs are in close contact with humans and wildlife. This study provides insight into viral communities and the prevalence and characteristics of enteric viral co-infections in smallholder pigs in East Africa. Sequence-independent amplification and high-throughput sequencing were applied to the metagenomics analysis of viruses in feces collected from asymptomatic pigs. A total of 47,213 de novo-assembled contigs were constructed and compared with sequences from the GenBank database. Blastx search results revealed that 1039 contigs (>200 nt) were related to viral sequences in the GenBank database. Of the 1039 contigs, 612 were not assigned to any viral taxa because they had little similarity to known viral genomic or protein sequences, while 427 contigs had a high level of sequence similarity to known viruses and were assigned to viral taxa. The most frequent contigs related to mammalian viruses resembling members of the viral genera Astrovirus, Rotavirus, Bocavirus, Circovirus, and Kobuvirus. Other less abundant contigs were related to members of the genera Sapelovirus, Pasivirus, Posavirus, Teschovirus and Picobirnavirus. This is the first report on the diversity of the fecal virome of pig populations in East Africa. The findings of the present study help to elucidate the etiology of diarrheal diseases in pigs and identify potential zoonotic and emerging viruses in the region. Further investigations are required to compare the incidence of these viruses in healthy and diseased pigs in order to better elucidate their pathogenic role.

Prevalence and genomic characterization of porcine parvoviruses detected in Chiangmai area of Thailand in 2011

Porcine parvovirus (PPV) causes reproductive failure in sows and has spread worldwide. Several new types of porcine parvoviruses have recently been identified in pig herds. The prevalence of five porcine parvoviruses in the Chiangmai area of Thailand was studied. The prevalence in 80 pigs was 53% for PPV (PPV-Kr or -NADL2 being the new abbreviations), 83% for PPV2 (CnP-PARV4), 73% for PPV3 (P-PARV4), 44% for PPV4 (PPV4), and 18% for PBo-likeV (PBoV7). Over 60% of the pigs carried more than three of the five porcine parvoviruses and occurrence together of the two pairs of viral genes, PPV1/PPV3 and PPV2/PBo-likeV were observed. Phylogenetic analyses for PPV2 and PPV3 indicated the existence of only two major clades of PPV2 and one major clade of PPV3.

A novel porcine bocavirus harbors a variant NP gene

Background

Porcine bocavirus is classified within the genus Bocaparvovirus, family Parvoviridae. Unlike other parvoviruses, the members of genus Bocaparvovirus (bocaparvoviruses) encode an additional open reading frame (NP1). Many strains of PBoVs have been identified in domestic pigs and recognized as a potential emerging pathogen causing respiratory and gastrointestinal disease.

Findings

A new strain of porcine bocavirus (PBoV) that harbored the shortest NP1 gene among all currently characterized PBoVs (provisionally named as ‘PBoV-KU14’) was detected in domestic pigs. Almost the complete genome sequence was obtained, approximately 4,630 nucleotides in lengths with putative NS1, NP1, and VP1/2 genes of 1,908, 600, 1,851 bp, respectively. Phylogenetic and comparative analysis was performed using protein and nucleotide sequences. It was revealed that PBoV-KU14 belongs to the genus Bocaparvovirus and species Ungulate bocaparvovirus 4. However, phylogenetic incongruence was observed among species classifications based on the NS1, NP1 and VP1/2 proteins, which indicates a probability of crossover recombination. Conserved protein domains unique for genus Bocaparvovirus in NP1, VP1 protein were also detected.

Conclusion

NP1 gene truncation supposed to be caused by cross over recombination was detected in a new strain of PBoV (PBoV-KU14). Considering high rates of substitution and recombination in parvovirus, periodic surveillance study to monitor genomic variation and find new strainsof PBoVs seems to be needed.

Coincidental detection of genomes of porcine parvoviruses and porcine circovirus type 2 infecting pigs in Japan

The infection status of 15 viruses in 120 pigs aged about 6 months was investigated based on tonsil specimens collected from a slaughterhouse. Only 5 species of porcine parvoviruses and porcine circovirus type 2 (PCV2) were detected at high frequencies; 67% for porcine parvovirus (PPV) (PPV-Kr or -NADL2 as the new abbreviation), 58% for PPV2 (CnP-PARV4), 39% for PPV3 (P-PARV4), 33% for PPV4 (PPV4), 55% for PBo-likeV (PBoV7) and 80% for PCV2. A phylogenetic analysis of PPV3 suggested that Japanese PPV3s showed a slight variation, and possibly, there were farms harboring homogeneous or heterogeneous PPV3s. Statistical analyses indicated that the detection of PCV2 was significantly coincidental with each detection of PPV, PPV2 and PPV3, and PPV and PPV4 were also coincidentally detected. The concurrent infection with PCV2 and porcine parvoviruses in the subclinically infected pigs may resemble the infection status of pigs with the clinical manifestations of porcine circovirus associated disease which occurs in 3–5 months old pigs and is thought to be primarily caused by the PCV2 infection.

Detection and characterisation of novel bocavirus (genus Bocaparvovirus) and gastroenteritis viruses from asymptomatic pigs in Ireland

Background

Livestock animals have been the assumed source of several human epidemics in recent years, for example, influenza H1N1, rotavirus G8/G9, and MERS-CoV. Surveillance of novel viruses in animals is essential to evaluate the risk to human and animal health and to determine any economic impact, for example, failure to thrive. There is a paucity of data regarding detection and characterisation of gastroenteritis viruses, particularly novel viruses, in porcines in Ireland. Recently, a number of small novel porcine DNA viruses have emerged globally, for example, torque teno sus virus, porcine bocavirus, and parvoviruses 2 & 4, and little is known about the biology and potential pathogenicity of these viruses. Bocaparvovirus is a genetically distinct group of viruses which has been recently detected in humans and animals.

Methods

In this study, the presence of gastroenteritis viruses (rotavirus A, porcine circovirus, adenovirus, and porcine bocavirus) was investigated in a selection of archived faecal samples from asymptomatic piglets from a commercial farm in Ireland. A total of 104 specimens were pooled and screened using conventional molecular techniques (PCR and RT-PCR), a subset of specimens (n=44) were then examined individually. Viral diversity was then investigated using statistical and phylogenetic techniques.

Results

Initial screening showed a high prevalence of PBoV in this farm, with the formation of three distinct groups in phylogenetic analysis. Other viruses were also investigated in this study with the first report of PCV, PAdV and lineage I G5 RVA in Ireland. Some specimens contained >1 virus, with statistical analysis indicating a strong correlation for mixed infections of PBoV and PAdV on this farm.

Conclusion

Investigating the diversity of circulating enteric viruses on Irish porcine farms is important to improve the prophylactic tools available and to facilitate the early detection of changes in circulating viruses.

Concurrent infections of pseudorabies virus and porcine bocavirus in China detected by duplex nanoPCR

Nanoparticle-assisted polymerase chain reaction (nanoPCR) is a novel method for the simple, rapid, and specific amplification of DNA and has been used to detect viruses. A duplex nanoPCR molecular detection system was developed to detect pseudorabies virus (PRV) and porcine bocavirus (PBoV). Primers were selected to target conserved regions within the PRV gE gene and the PBoV NS1 gene. Under optimized nanoPCR reaction conditions, two specific fragments of 316 bp (PRV) and 996 bp (PBoV) were amplified by the duplex nanoPCR with a detection limit of 6 copies for PRV and 95 copies for PBoV; no fragments were amplified when other porcine viruses were used as template. When used to test 550 clinical samples, the duplex nanoPRC assay and a conventional duplex PCR assay provided very similar results (98.1% consistency); single PRV infections, single PBoV infections, and concurrent PRV and PBoV infections were detected in 37%, 15%, and 9% of the samples, respectively. The results indicate that the novel duplex nanoPCR assay is useful for the rapid detection of PRV and PBoV in pigs.

Porcine bocavirus: achievements in the past five years

Porcine bocavirus is a recently discovered virus that infects pigs and is classified within the Bocavirus genus (family Parvoviridae, subfamily Parvovirinae). The viral genome constitutes linear single-stranded DNA and has three open reading frames that encode four proteins: NS1, NP1, VP1, and VP2. There have been more than seven genotypes discovered to date. These genotypes have been classified into three groups based on VP1 sequence. Porcine bocavirus is much more prevalent in piglets that are co-infected with other pathogens than in healthy piglets. The virus can be detected using PCR, loop-mediated isothermal amplification, cell cultures, indirect immunofluorescence, and other molecular virology techniques. Porcine bocavirus has been detected in various samples, including stool, serum, lymph nodes, and tonsils. Because this virus was discovered only five years ago, there are still many unanswered questions that require further research. This review summarizes the current state of knowledge and primary research achievements regarding porcine bocavirus.

Evolutionary, epidemiological, demographical, and geographical dissection of porcine bocavirus in China and America

Porcine bocavirus was first discovered in Swedish pigs with post-weaning multisystemic wasting syndrome (PMWS) in 2009. Many efforts have been implemented to investigate the porcine bocavirus, but it remains enigmatic. In the current study, we utilized data from both China and the USA. The China-derived data included 403 pig samples collected from five provinces, 122 gene sequences from the GenBank database, and 637 old porcine bocavirus (PBoV) cases. The USA-derived data comprised 181 pig samples from 18 states, 39 new gene sequences, and 85 new emerging cases. First, we executed a comprehensive analysis of the disease's prevalence, phylogenetics, evolutionary distances, mutation network, geographical distribution, occurrence frequency, and phylogeographical estimation in both China and the USA. The results showed that the positive rates of PBoV (42.0%, 76/181) in American samples were significantly higher than those (11.4%, 46/403) in the Chinese samples. All PBoV cases from these countries can be divided into six groups: PBoV1 (group 1), PBoV2 (group 2), PBoV3C (group 3), PBoV5 (group 4), PBoV3/4 (group 5), and PBoV6V7V (group 6). PBoV1 and PBoV2 were epidemic strains from 2006 to 2011 in China, whereas the PBoV3 subtypes were epidemic from 2010 to 2012 in China and the USA. At present, PBoV3C (group 3), PBoV5 (group 4), and PBoV3/4 (group 5) are epidemic viruses and co-exist in China and the USA. The geographical distribution of PBoV mainly lies in the east and south coastal areas of China and the central states of the USA. Jiangsu Province and the state of Minnesota were the centers of high occurrence frequency of PBoV with six outbreaks. The old PBoV cases involved 14 provinces and regions of China and North Carolina in the USA, whereas the new emerging cases involved five provinces in China and 13 states in the USA, of which two provinces and 12 states reported for the first time that piglets were infected by PBoV. Hong Kong, Hebei, and Jiangsu Provinces and the states of Minnesota and North Carolina were possibly geographical origins of PBoV in China and America, respectively. These data can help us systematically understand porcine bocavirus in China and America and find effective strategies for its treatment.

A new nanoPCR molecular assay for detection of porcine bocavirus

Nanoparticle-assisted polymerase chain reaction (nanoPCR) is a novel method for the rapid amplification of DNA and has been used for the detection of virus. For detection of porcine bocavirus (PBoV), a sensitive and specific nanoPCR assay was developed with a pair of primers that were designed based on NS1 gene sequences available in GenBank. Under the optimized conditions of the PBoV nanoPCR assay, the nanoPCR assay was 100-fold more sensitive than a conventional PCR assay. The lower detection limit of the nanoPCR assay was about 6.70×10(1) copies. The nanoPCR assay amplified the specific 482-bp fragment of the PBoV NS1 recombinant plasmid but did not produce any product with genomic DNA or cDNA of porcine parvovirus, porcine circovirus type II, porcine reproductive and respiratory syndrome virus, pseudorabies virus, classic swine fever virus, Encephalomyocarditis virus, Porcine Teschovirus or African swine fever virus plasmid. Of 65 clinical samples collected from diseased pigs, 73.8% and 86.2% were determined to be PBoV positive by PBoV conventional PCR and PBoV nanoPCR assay, respectively. Of 36 clinical samples from healthy pigs, 27.8% and 44.4% were PBoV positive by PBoV conventional PCR and PBoV nanoPCR assay, respectively. The nanoPCR assay will be useful for diagnosing PBoV and for studying its epidemiology and pathology.

Complete sequence and phylogenetic analysis of a porcine bocavirus strain swBoV CH437

Porcine bocavirus (PBoV), a member of genus Bocavirus, family Parvoviridae, was first identified in 2009 in Swedish swine herds suffering from postweaning multisystemic wasting syndrome. Up to date, the different species of PBoVs have been reported in different countries. Especially, the virus isolated in China was complicated. In this study, we detected a novel PBoV strain swBoV CH437 from clinical samples collected in Gansu Province, Northwest China. The complete genome of swBoV CH437 was 5,275 nucleotides (nt) in length and contains three ORFs: ORF1 encodes NS1 (2,004 nt, 667 aa), ORF3 encodes NP1 (681 nt, 226 aa), and ORF2 encodes VP1 (2,049 nt, 682 aa) and VP2 (1,641 nt, 546 aa). Sequence analysis demonstrated that the NS1 gene shared 24.2-88.6 % nucleotide sequence identity, the NP1 shared 21.3-89.9 %, less than 95 % nucleotide sequence identity with other PBoV strains. Therefore, we propose that swBoV CH437 should be classified as a novel PBoV species.

Detection and characterization of porcine bocavirus in the United States

We screened pigs (n = 203) presenting with respiratory illness or diarrhea for porcine bocavirus (PBoV); 88 (43.30 %) were positive by PCR. More positives were seen in diarrhea cases (48.7 %) than in respiratory cases (29.1 %). Based on phylogenetic analysis of 540 nucleotides of the NS1 gene, the viruses could be divided into four possible groups. Group IV sequences did not match any GenBank sequences, while groups I, II and III gave matches with PBoV3, PBoV4 and PBoV5, respectively. The wide range (70 % to 100 %) of nucleotide (nt) sequence identity among strains in this study indicates high genetic diversity among porcine bocaviruses.

Identification of multiple novel viruses, including a parvovirus and a hepevirus, in feces of red foxes

Red foxes (Vulpes vulpes) are the most widespread members of the order of Carnivora. Since they often live in (peri)urban areas, they are a potential reservoir of viruses that transmit from wildlife to humans or domestic animals. Here we evaluated the fecal viral microbiome of 13 red foxes by random PCR in combination with next-generation sequencing. Various novel viruses, including a parvovirus, bocavirus, adeno-associated virus, hepevirus, astroviruses, and picobirnaviruses, were identified.

Characterization of a novel porcine parvovirus tentatively designated PPV5

A new porcine parvovirus (PPV), provisionally designated as PPV5, was identified in U.S. pigs. Cloning and sequencing from a circular or head-to-tail concatemeric array revealed that the PPV5 possesses the typical genomic organization of parvoviruses with two major predicted open reading frames (ORF1 and ORF2), and is most closely related to PPV4 with overall genomic identities of 64.1–67.3%. The amino acid identities between PPV5 and PPV4 were 84.6%–85.1% for ORF1 and 54.0%–54.3% for ORF2. Unlike PPV4, but similar to bovine parvovirus 2 (BPV2), PPV5 lacks the additional ORF3 and has a much longer ORF2. Moreover, the amino acid sequences of ORF1 and ORF2 of BPV2 showed higher homologies to PPV5 than to PPV4. The conserved motifs of the Ca²⁺ binding loop (YXGXG) and the catalytic center (HDXXY) of phospholipase A₂ (PLA₂) were identified in VP1 (ORF2) of PPV5, as well as in BPV2, but were not present in PPV4. Phylogenetic analyses revealed that PPV5, PPV4 and BPV2 form a separate clade different from the genera Parvovirus and Bocavirus. Further epidemiologic investigations of PPV4 and PPV5 in U.S. pigs of different ages indicated a slightly higher prevalence for PPV5 (6.6%; 32/483) compared to PPV4 (4.1%; 20/483), with detection of concurrent PPV4 and PPV5 in 15.6% (7/45) of lungs of infected pigs. Evidence for potential vertical transmission or association with reproductive failure was minimal for both PPV4 and PPV5. The high similarity to PPV4 and the lack of ORF3 may suggest PPV5 is an intermediate of PPV4 during the evolution of parvoviruses in pigs.

Detection of a porcine boca-like virus in combination with porcine circovirus type 2 genotypes and Torque teno sus virus in pigs from postweaning multisystemic wasting syndrome (PMWS)-affected and non-PMWS-affected farms in archival samples from Great Britain

In this study we detail the detection and genetic analysis of a novel porcine boca-like virus (PBo-likeV) in archival sera and tissue samples from pigs from farms in Great Britain. We also investigate the distribution of porcine circovirus type 2 (PCV2) genotypes and Torque teno sus virus (TTSuV) genogroups 1 and 2 in combination with this novel PBo-likeV. PBo-likeV was detected in over 70% of all tissues investigated. Over 24% of all tissues recovered from PMWS-affected animals had all viruses present and 25% of tissues recovered from non-PMWS-affected pigs were positive for all 4 viruses.

Genetic characterisation of a porcine bocavirus detected in domestic pigs in Uganda

Porcine bocaviruses (PoBoVs) are small linear ssDNA viruses belonging to the genus bocavirus in the family Parvoviridae. The genome encodes four proteins—the non-structural protein 1 (NS1), the NP1 protein (unknown function) and the two structural proteins VP1 and VP2. In recent years, a number of different highly divergent PoBoV species have been discovered. PoBoVs have been shown to be present in pig populations in Europe, Asia and in the United States of America. In this study, we present the first data of the presence of PoBoV in Africa, specifically in Uganda. A PCR targeting a PoBoV species that have previously been detected in both Sweden and China was used to screen 95 serum samples from domestic pigs in Uganda. Two pigs were found to be positive for this specific PoBoV and the complete coding region was amplified from one of these samples. The amino acid sequence comparison of all these proteins showed a high identity (98–99 %) to the published Chinese sequences (strains: H18 and SX) belonging to the same PoBoV species. The same was true for the Swedish sequences from the same species. To the other PoBoV species the divergence was higher and only a 28–43 % protein sequence identity was seen comparing the different proteins.

Genome characterization of a novel porcine bocavirus

Using a high-throughput DNA sequencing method, one DNA sequence (contig01006), suspected to belong to a novel porcine bocavirus (PBoV), was found with a high rate of detection (19.6 %) in fecal samples from healthy piglets. Moreover, a novel PBoV (tentatively named PBoV3C) with a nearly complete genome sequence (5235 bp) was identified. PBoV3C exhibits typical genome characteristics of bocaviruses and shows the highest genomic sequence identity (78 % to 81 %) to PBoV3A/B (PBoV3/4-UK) and PBoV3D/E (PBoV3/4-HK), respectively. Phylogenetic and recombination analysis indicated high diversity, prevalence and complexity among the PBoVs. The phospholipase A2 (PLA2) site of VP1 and the secondary structure of VP2 of PBoV3C were also analyzed. Additionally, we propose a uniform method of PBoV nomenclature based on the VP1 gene.

Identification and characterization of bocaviruses in cats and dogs reveals a novel feline bocavirus and a novel genetic group of canine bocavirus

We report the identification and genome characterization of a novel bocavirus, feline bocavirus (FBoV), and novel bocaviruses closely related to canine bocavirus (CBoV) strain Con-161 in stray cats and dogs in Hong Kong, respectively. FBoV was detected by PCR in 7.2, 0.3, 1.6, 2.0 and 0.8% of faecal, nasal, urine, kidney and blood samples, respectively, from 364 cats, while CBoV was detected in 4.6, 5.1, 6.3 and 0.3% of faecal, nasal, urine and blood samples, respectively, from 351 dogs. Three FBoV genomes sequenced revealed the presence of three ORFs characteristic of bocaviruses. Phylogenetic analysis showed that FBoVs were related only distantly to other bocaviruses, forming a distinct cluster within the genus, with ≤ 5.7% nucleotide identities to the genome of minute virus of canines. The four CBoV genomes sequenced shared 87.4-89.2% nucleotide identities with that of CBoV strain Con-161. In addition to the three bocavirus ORFs, they encoded an additional ORF, ORF4, immediately downstream of the ORF for non-structural protein 1 (NS1), which was not found in other bocaviruses including CBoV strain Con-161. They also possessed a putative second exon encoding the C-terminal region of NS1 and conserved RNA-splicing signals, previously described in human bocaviruses. Partial VP1/VP2 sequence analysis of 23 FBoV and 25 CBoV strains demonstrated inter-host genetic diversity, with two potential genetic groups of FBoV and a novel CBoV group, CBoV-HK, distinct from the three groups, CBoV-A to -C, found in the USA. Although the pathogenicity of FBoV and CBoV remains to be determined, their presence in different host tissues suggested wide tissue tropism.

Complete genome sequence of a novel species of Porcine Bocavirus, PBoV5

Porcine bocavirus 5 is a novel porcine bocavirus species found in a pig with clinical diarrhea from a farm in China. Here, we report the complete genome sequence of strain PBoV5/JS677, which will help toward understanding the molecular and evolutionary characteristics of the porcine bocavirus.

Emerging and re-emerging swine viruses

In the past two decades or so, a number of viruses have emerged in the global swine population. Some, such as porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2), cause economically important diseases in pigs, whereas others such as porcine torque teno virus (TTV), now known as Torque teno sus virus (TTSuV), porcine bocavirus (PBoV) and related novel parvoviruses, porcine kobuvirus, porcine toroviruses (PToV) and porcine lymphotropic herpesviruses (PLHV), are mostly subclinical in swine herds. Although some emerging swine viruses such as swine hepatitis E virus (swine HEV), porcine endogenous retrovirus (PERV) and porcine sapovirus (porcine SaV) may have a limited clinical implication in swine health, they do pose a potential public health concern in humans due to zoonotic (swine HEV) or potential zoonotic (porcine SaV) and xenozoonotic (PERV, PLHV) risks. Other emerging viruses such as Nipah virus, Bungowannah virus and Menangle virus not only cause diseases in pigs but some also pose important zoonotic threat to humans. This article focuses on emerging and re-emerging swine viruses that have a limited or uncertain clinical and economic impact on pig health. The transmission, epidemiology and pathogenic potential of these viruses are discussed. In addition, the two economically important emerging viruses, PRRSV and PCV2, are also briefly discussed to identify important knowledge gaps.

Development of a loop-mediated isothermal amplification method for rapid detection of porcine boca-like virus

The porcine boca-like virus (Pbo-likeV) was recently discovered in Swedish pigs with post-weaning multisystemic wasting syndrome (PMWS). In this study, a loop-mediated isothermal amplification (LAMP) assay was developed for rapid, specific and sensitive detection of Pbo-likeV. A set of four primers specific for six regions of Pbo-likeV VP1/2 genes was designed with the online software. The reaction temperature and time were optimized to 65 °C and 60 min, respectively. LAMP products were detected by agarose gel electrophoresis or by visual inspection of a color change due to addition of fluorescent dye. The developed method was highly specific for detection of Pbo-likeV, and no cross-reaction was observed with other swine viruses, such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), porcine parvovirus (PPV) and classic swine fever virus (CSFV) found commonly in China. The lower detection limit of the LAMP assay was approximately 10 copies per reaction, and it was 100 times more sensitive than that of conventional PCR. Furthermore, the efficiency of LAMP for detection Pbo-likeV in clinical samples was comparable to PCR and sequencing. These results showed that the LAMP assay is a simple, rapid, sensitive and specific technique for detection of Pbo-likeV, and the procedure of LAMP does not rely on any special equipment. It has capacity for the detection of Pbo-likeV both in the laboratory and on farms.

The fecal virome of pigs on a high-density farm

Swine are an important source of proteins worldwide but are subject to frequent viral outbreaks and numerous infections capable of infecting humans. Modern farming conditions may also increase viral transmission and potential zoonotic spread. We describe here the metagenomics-derived virome in the feces of 24 healthy and 12 diarrheic piglets on a high-density farm. An average of 4.2 different mammalian viruses were shed by healthy piglets, reflecting a high level of asymptomatic infections. Diarrheic pigs shed an average of 5.4 different mammalian viruses. Ninety-nine percent of the viral sequences were related to the RNA virus families Picornaviridae, Astroviridae, Coronaviridae, and Caliciviridae, while 1% were related to the small DNA virus families Circoviridae, and Parvoviridae. Porcine RNA viruses identified, in order of decreasing number of sequence reads, consisted of kobuviruses, astroviruses, enteroviruses, sapoviruses, sapeloviruses, coronaviruses, bocaviruses, and teschoviruses. The near-full genomes of multiple novel species of porcine astroviruses and bocaviruses were generated and phylogenetically analyzed. Multiple small circular DNA genomes encoding replicase proteins plus two highly divergent members of the Picornavirales order were also characterized. The possible origin of these viral genomes from pig-infecting protozoans and nematodes, based on closest sequence similarities, is discussed. In summary, an unbiased survey of viruses in the feces of intensely farmed animals revealed frequent coinfections with a highly diverse set of viruses providing favorable conditions for viral recombination. Viral surveys of animals can readily document the circulation of known and new viruses, facilitating the detection of emerging viruses and prospective evaluation of their pathogenic and zoonotic potentials.

Human bocavirus: still more questions than answers

The human bocavirus was first detected in 2005 and since then has been found in both respiratory secretions from patients with airway infections and in stool samples from patients with gastroenteritis. Meanwhile, four different genotypes have been identified that most likely derive from recombination events. Although the modified Koch’s postulates have not yet been fulfilled completely, owing to the lack of an animal model or a simple cell culture system, there is increasing evidence that the human bocaviruses are serious participants in infectious diseases of the respiratory and the GI tracts. This article reviews the current status of the clinical features of human bocaviruses and provides an overview of the latest findings concerning the biology, phylogeny, epidemiology and diagnostic tools related to human bocaviruses. Furthermore, it discusses the potential pathogenicity of human bocavirus, as well as its persistence and reactivation in hosts.