Virus Genes (2014) 48:387–390 DOI 10.1007/s11262-013-1032-x
Complete sequence and phylogenetic analysis of a porcine bocavirus strain swBoV CH437 Enli Wang • Wei Liu • Bin Yang • Jixing Liu Xiaojun Ma • Xi Lan
•
Received: 28 September 2013 / Accepted: 31 December 2013 / Published online: 28 January 2014 Ó Springer Science+Business Media New York 2014
Abstract 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. Keywords Porcine bocavirus Complete genome Sequence analysis Northwest China
Enli Wang and Wei Liu contributed equally to this study. E. Wang W. Liu B. Yang J. Liu X. Lan (&) State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China e-mail: [email protected] E. Wang X. Ma College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
Introduction The family Parvoviridae is divided into two subfamilies: Parvovirinae, viruses which infect vertebrates, and Densovirinae, viruses which infect insects and other arthropods. Parvovirinae is divided into five genera: Amdovirus, Dependovirus, Erythrovirus, Parvovirus, and Bocavirus. Two new genera, Hokovirus and Cnvirus, have been proposed as members of subfamily Parvovirinae [1– 5]. To date, bocaviruses have been detected in humans [6] (HBoV) and many kinds of animals, such as canine (CnMV) [7], bovine (BPV) [8], swine (PBoV) [9], gorillas (GBoV) [10], and California sea lions (CslBoV) [11]. Bocaviruses are non-enveloped DNA viruses, 26 nm in diameter and containing a single-stranded genome of approximate length 5 kb [12]. The genome consists of three open reading frames (ORFs): ORF1, ORF2, and ORF3. ORF1 and ORF3 encode two nonstructural proteins, NS1 and NP1, respectively. ORF2 encodes the caspid protein, VP1/VP2 [6–8]. Porcine bocavirus (PBoV) was first identified in 2009 in Swedish swine herds suffering from postweaning multisystemic wasting syndrome (PMWS) [9]. Since this initial discovery, novel PBoVs have been reported in America [13], Hong Kong and Northern Ireland (PBoV3 and PBoV4) [14, 15]. Recently, a newly identified species PBoV5 was isolated from a farm in China [16]. Based on the results of these studies, PBoVs, the suspected causative agents of diarrheal illness in piglets, have been classified as family Parvoviridae, subfamily Parvovirinae, genus Bocavirus. In the present study, the complete nucleotide sequence of swBoV CH437 was determined and the relationship with other members of subfamily Parvovirinae was established. The complete sequence of PBoV strain swBoV CH437 was submitted to GenBank under accession number KF360033.
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Materials and methods Specimens and primers Porcine fecal specimens were collected from pig farms in Wuwei, Tianshui, Jingtai, Jiayuguan, Gansu Province, China, in 2012. PBoV strain swBoV CH437 was selected for characterization of the complete genome. Eight sets of primers based on the complete genome sequences of PBoV strains (JF429834, JF429836, JF713715, NC_016032) were logged in GenBank. The primers are listed in Table 1. DNA extraction, genomic amplification, and cloning The total DNA was extracted from 400 lL of 10 % fecal suspension using DNA/RNA Isolation Kit (TIANGEN, Beijing, China) according to the manufacturer’s instructions. PCR was carried out in 50 lL reaction volume: 25 lL One Step Premix TaqÒ (TaKaRa, Dalian, China), 7 lL DNA template, 1 lL of each primer (50 lM), 17 lL ddH2O. The reaction conditions were as follows: 5 min of initial denaturation at 94 °C, followed by 35 cycles of denaturation at 94 °C for 30 s, annealing at 50 °C for 40 s, extension at 72 °C for 2 min, and then followed by a final extension step at 72 °C for 10 min. The PCR products were visualized on a 1.0 % (w/v) agarose gel, and the excised amplicons were purified using an AxyPrep DNA Gel Extraction Kit (Axygene, Hangzhou, China). The amplicons were cloned into the pGEM-T Easy Vector (Promega, Beijing, China) at 16 °C for 4 h. Escherichia coli JM 109 cells (TaKaRa) were transformed with the recombinant Table 1 Primers used for amplification and sequencing of the strain swBoV CH437 Primer name
Position
Nucleotide sequence (50 –30 )
S1
1–23
CCCACACAAGGAAATAAGTATCG
A1
379–398
CCAGTAATAGCTCCGTGCCA
S2
378–397
TTGGCACGGAGCTATTACTG
A2
1,637–1,655
GCCGGACCAAAGAAACAGA
S3
1,522–1,540
ATCAAGCCGGAGAATAAGG
A3
2,230–2,248
CACCGTCGCTGGTAGTAGT
S4
2,179–2,196
GTGCTCTACGCTCAAGGA
A4
2,818–2,800
GGAGTGATAGTAAAACCCA
S5
2,711–2,728
TGGAAGAGCCGCAAGATG
A5
3,344–3,361
TTACCGCCCACAGAAGAG
S6
3,344–3,361
CTCTTCTGTGGGCGGTAA
A6
4,036–4,053
TCCAAGGAAAGGCGTGTT
S7
4,036–4,052
AACACGCCTTTCCTTGG
A7
4,906–4,923
TGACGTAGATGGTTCCCG
S8 A8
4,900–4,919 5,256–5,278
ATCCTCCGGGAACCATCTAC CCCATCACCACCCACATAAAAAT
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plasmid as per the manufacturer’s instructions and cultured at 37 °C overnight. Positive colonies were isolated using blue/white screening, and the recombinant plasmids were extracted from cells using Axyprep Plasmid Miniprep Kit (Axygene). Recombinant plasmids isolated from a minimum of three positive colonies were submitted for sequencing.
Sequencing and phylogenetic analysis Sequences were checked using BLAST (http://www.ncbi. nlm.nig.gov/BLAST). A total of eight segments were aligned using ClustalW within the MEGA5 software package [17]. This software was also used to calculate the genetic distances and construct phylogenetic trees using the neighbor-joining method, maximum likelihood method, and minimum evolution method with 1,000 bootstrap replicates [18].
Results The complete genome length of PBoV strain swBoV CH437 was determined as 5,275 nucleotides (nt) with base composition: 27.3 % A, 21.55 % T, 26.73 % G, and 24.42 % C. And with other bocaviruses, the genome of swBoV CH437 contained three ORFs. The 2,004 nt ORF1 encoded the nonstructural protein NS1 (667 aa), ORF2 the structural protein VP1/2 (682 aa and 546 aa, respectively), and ORF3 (681 nt) encoded NP1 (226 aa). The entire genome sequence of swBoV CH437 was compared with representative strains of subfamily Parvovirinae (Table 2). It can be seen from the phylogenetic tree (Fig. 1) that swBoV CH437 was more closely related to the members of genus Bocavirus than to any other genera. Analysis of nucleotide sequences demonstrated that swBoV CH437 shared high nucleotide sequence identity with bocaviruses (37.0–86.9 %), but lower identity with other genera of Parvovirinae (\35 %). Based on these results, we can surmise that swBoV CH437 belongs to the genus Bocavirus. To date, PBoVs have been classified into five genogroups [13–16, 19]. We therefore compared the complete genome sequence and three ORFs (NS1, NP1, and VP1/2) of strain swBoV CH437 with five typical strains of PBoV retrieved from GenBank. Phylogenetic trees produced for each of these analyses are presented in Fig. 2. Sequence analysis showed that the complete genome of swBoV CH437 shared 37.0–86.9 % nucleotide identity with the PBoVs strains. The ORFs for NS1, NP1 and VP1/2 of swBoV CH437 shared 24.2–88.6, 21.3–89.9, 22.5–87.2 % nucleotide sequences identity and 18.0–89.1, 10.2–85.5,
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Table 2 The whole genome sequences of representative strains of genera such as Bocavirus, Amdovirus, Dependovirus, Erythrovirus, Hokovirus, and Parvovirusand selected for sequence analysis Host
Stain
Accession number
Genus/ genogroup
Human
St1
DQ000495
BoV/HBoV1
Human bocavirus 2
NC_012042
BoV/HBoV2
Human bocavirus 3
NC_012546
BoV/HBoV3
Human bocavirus 4
NC_012729
BoV/HBoV4 BoV/PBoV1
Swine
H18
HQ291308
ZJD
HM053694
BoV/PBoV2
SH20F
JF429834
BoV/PBoV3
F41
JF512473
BoV/PBoV4
JS677
JN831651
BoV/PBoV5
Gorilla
GBoV1
HM145750
BoV/GBoV
Sea lion
1136
JN420360
BoV/CslBoV
Bovine
Bovine parvovirus
M14363
BoV/BPV
Canine Mink
GA3 AMDV
FJ214110 NC_001662
BoV/CnMV Amdovirus
Human
B19
AF162273
Erythrovirus
Human
V9
NC_004295
Erythrovirus
Bovine
HK1
EU200669
Hokovirus
Swine
HK2
EU200672
Hokovirus
Goose
GPV
NC_001701
Dependovirus
Duck
MDPV
NC_006147
Dependovirus
Mouse
MPV
NC_001630
Parvovirus
Swine
PPV
NC_001718
Parvovirus
Fig. 2 Phylogenetic trees of complete genome sequence (a), NS1 (b), NP1 (c), and VP1/2 (d) of strain swBoV CH437 and strains of the five genogroups of PBoV. The trees were constructed using neighborjoining clustering method with 1,000 bootstrap replicates Fig. 1 A neighbor-joining tree constructed using MEGA 5 with 1,000 bootstrap replicates for the full-length genome sequence from members of the family Parvoviridae. The strain swBoV CH437 belongs to the genus Bocavirus
11.9–90.0 % amino acid similarity, respectively. The International Committee on Taxonomy of Viruses (ICTV) has stipulated a species demarcation criteria for members
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of the genus Bocavirus (\95 % sequence identity in nonstructural gene nucleotide sequences). Based on the results obtained we conclude that swBoV CH437 should be classified as a novel PBoV species.
Discussion Porcine bocavirus is responsible for gastroenteritis in swine. Since its first detection in Sweden [9], PBoV has been isolated in America [13], Northern Ireland [15], Uganda [20], Rumania [21], and most notably in China in recent years. In 2010, Zhai et al. [22] reported a PBoV-like virus positivity rate of 38.7 % in pigs suffering from respiratory tract symptoms, and 7.3 % in healthy pigs during a survey of nine provinces in China. In the same year, a serological investigation showed a high prevalence (nearly 40 %) of PBoV-like virus in clinically normal pigs in Hubei Province, China [23]. In addition, Zhang et al. [24] collected 166 samples across ten provinces of China for type testing. Their results showed that four types of PBoV were prevalent in Chinese swine: 28.9 % PBoV1, 6.6 % PBoV2, 19.3 % PBoV3, and 39.7 % PBoV4. According to a report by Shan et al. [25], the positive rate of PBoV detection across five provinces of China was 45–75 %, indicating that PBoV infection in China was both prevalent and complicated. Porcine bocavirus has been detected across a total of 14 provinces in China, including Zhejiang, Jiangxi, Anhui, Hebei, Henan, Jiangsu, Beijing, Shanghai, Xinjiang, Shandong, Guizhou, Fujian, Guangxi, and Hubei. To our knowledge, swBoV CH437 was the first PBoV strain to be detected from Gansu Province, Northwest China. In this study, the complete genome of swBoV CH437 was sequenced and analyzed. The full genome length of strain swBoV CH437 was 5,275 nt; the complete genome sequence of swBoV CH437 shared 24.2–88.6 % nucleotide sequence identity in NS1 region, and NP1 of 21.3–89.9 % nucleotide sequence identity, with representative strains of five genogroups of PBoV. Collectively these results demonstrated that a novel species of PBoV was isolated from swine in Gansu Province, Northwest China. We believe that the results obtained in this study will enrich our understanding of PBoV and will help facilitate future investigations of the evolutionary characteristics of PBoV.
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Complete sequence and phylogenetic analysis of a porcine bocavirus strain swBoV CH437 Enli Wang • Wei Liu • Bin Yang • Jixing Liu Xiaojun Ma • Xi Lan
•
Received: 28 September 2013 / Accepted: 31 December 2013 / Published online: 28 January 2014 Ó Springer Science+Business Media New York 2014
Abstract 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. Keywords Porcine bocavirus Complete genome Sequence analysis Northwest China
Enli Wang and Wei Liu contributed equally to this study. E. Wang W. Liu B. Yang J. Liu X. Lan (&) State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Grazing Animal Diseases, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China e-mail: [email protected] E. Wang X. Ma College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
Introduction The family Parvoviridae is divided into two subfamilies: Parvovirinae, viruses which infect vertebrates, and Densovirinae, viruses which infect insects and other arthropods. Parvovirinae is divided into five genera: Amdovirus, Dependovirus, Erythrovirus, Parvovirus, and Bocavirus. Two new genera, Hokovirus and Cnvirus, have been proposed as members of subfamily Parvovirinae [1– 5]. To date, bocaviruses have been detected in humans [6] (HBoV) and many kinds of animals, such as canine (CnMV) [7], bovine (BPV) [8], swine (PBoV) [9], gorillas (GBoV) [10], and California sea lions (CslBoV) [11]. Bocaviruses are non-enveloped DNA viruses, 26 nm in diameter and containing a single-stranded genome of approximate length 5 kb [12]. The genome consists of three open reading frames (ORFs): ORF1, ORF2, and ORF3. ORF1 and ORF3 encode two nonstructural proteins, NS1 and NP1, respectively. ORF2 encodes the caspid protein, VP1/VP2 [6–8]. Porcine bocavirus (PBoV) was first identified in 2009 in Swedish swine herds suffering from postweaning multisystemic wasting syndrome (PMWS) [9]. Since this initial discovery, novel PBoVs have been reported in America [13], Hong Kong and Northern Ireland (PBoV3 and PBoV4) [14, 15]. Recently, a newly identified species PBoV5 was isolated from a farm in China [16]. Based on the results of these studies, PBoVs, the suspected causative agents of diarrheal illness in piglets, have been classified as family Parvoviridae, subfamily Parvovirinae, genus Bocavirus. In the present study, the complete nucleotide sequence of swBoV CH437 was determined and the relationship with other members of subfamily Parvovirinae was established. The complete sequence of PBoV strain swBoV CH437 was submitted to GenBank under accession number KF360033.
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Materials and methods Specimens and primers Porcine fecal specimens were collected from pig farms in Wuwei, Tianshui, Jingtai, Jiayuguan, Gansu Province, China, in 2012. PBoV strain swBoV CH437 was selected for characterization of the complete genome. Eight sets of primers based on the complete genome sequences of PBoV strains (JF429834, JF429836, JF713715, NC_016032) were logged in GenBank. The primers are listed in Table 1. DNA extraction, genomic amplification, and cloning The total DNA was extracted from 400 lL of 10 % fecal suspension using DNA/RNA Isolation Kit (TIANGEN, Beijing, China) according to the manufacturer’s instructions. PCR was carried out in 50 lL reaction volume: 25 lL One Step Premix TaqÒ (TaKaRa, Dalian, China), 7 lL DNA template, 1 lL of each primer (50 lM), 17 lL ddH2O. The reaction conditions were as follows: 5 min of initial denaturation at 94 °C, followed by 35 cycles of denaturation at 94 °C for 30 s, annealing at 50 °C for 40 s, extension at 72 °C for 2 min, and then followed by a final extension step at 72 °C for 10 min. The PCR products were visualized on a 1.0 % (w/v) agarose gel, and the excised amplicons were purified using an AxyPrep DNA Gel Extraction Kit (Axygene, Hangzhou, China). The amplicons were cloned into the pGEM-T Easy Vector (Promega, Beijing, China) at 16 °C for 4 h. Escherichia coli JM 109 cells (TaKaRa) were transformed with the recombinant Table 1 Primers used for amplification and sequencing of the strain swBoV CH437 Primer name
Position
Nucleotide sequence (50 –30 )
S1
1–23
CCCACACAAGGAAATAAGTATCG
A1
379–398
CCAGTAATAGCTCCGTGCCA
S2
378–397
TTGGCACGGAGCTATTACTG
A2
1,637–1,655
GCCGGACCAAAGAAACAGA
S3
1,522–1,540
ATCAAGCCGGAGAATAAGG
A3
2,230–2,248
CACCGTCGCTGGTAGTAGT
S4
2,179–2,196
GTGCTCTACGCTCAAGGA
A4
2,818–2,800
GGAGTGATAGTAAAACCCA
S5
2,711–2,728
TGGAAGAGCCGCAAGATG
A5
3,344–3,361
TTACCGCCCACAGAAGAG
S6
3,344–3,361
CTCTTCTGTGGGCGGTAA
A6
4,036–4,053
TCCAAGGAAAGGCGTGTT
S7
4,036–4,052
AACACGCCTTTCCTTGG
A7
4,906–4,923
TGACGTAGATGGTTCCCG
S8 A8
4,900–4,919 5,256–5,278
ATCCTCCGGGAACCATCTAC CCCATCACCACCCACATAAAAAT
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plasmid as per the manufacturer’s instructions and cultured at 37 °C overnight. Positive colonies were isolated using blue/white screening, and the recombinant plasmids were extracted from cells using Axyprep Plasmid Miniprep Kit (Axygene). Recombinant plasmids isolated from a minimum of three positive colonies were submitted for sequencing.
Sequencing and phylogenetic analysis Sequences were checked using BLAST (http://www.ncbi. nlm.nig.gov/BLAST). A total of eight segments were aligned using ClustalW within the MEGA5 software package [17]. This software was also used to calculate the genetic distances and construct phylogenetic trees using the neighbor-joining method, maximum likelihood method, and minimum evolution method with 1,000 bootstrap replicates [18].
Results The complete genome length of PBoV strain swBoV CH437 was determined as 5,275 nucleotides (nt) with base composition: 27.3 % A, 21.55 % T, 26.73 % G, and 24.42 % C. And with other bocaviruses, the genome of swBoV CH437 contained three ORFs. The 2,004 nt ORF1 encoded the nonstructural protein NS1 (667 aa), ORF2 the structural protein VP1/2 (682 aa and 546 aa, respectively), and ORF3 (681 nt) encoded NP1 (226 aa). The entire genome sequence of swBoV CH437 was compared with representative strains of subfamily Parvovirinae (Table 2). It can be seen from the phylogenetic tree (Fig. 1) that swBoV CH437 was more closely related to the members of genus Bocavirus than to any other genera. Analysis of nucleotide sequences demonstrated that swBoV CH437 shared high nucleotide sequence identity with bocaviruses (37.0–86.9 %), but lower identity with other genera of Parvovirinae (\35 %). Based on these results, we can surmise that swBoV CH437 belongs to the genus Bocavirus. To date, PBoVs have been classified into five genogroups [13–16, 19]. We therefore compared the complete genome sequence and three ORFs (NS1, NP1, and VP1/2) of strain swBoV CH437 with five typical strains of PBoV retrieved from GenBank. Phylogenetic trees produced for each of these analyses are presented in Fig. 2. Sequence analysis showed that the complete genome of swBoV CH437 shared 37.0–86.9 % nucleotide identity with the PBoVs strains. The ORFs for NS1, NP1 and VP1/2 of swBoV CH437 shared 24.2–88.6, 21.3–89.9, 22.5–87.2 % nucleotide sequences identity and 18.0–89.1, 10.2–85.5,
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Table 2 The whole genome sequences of representative strains of genera such as Bocavirus, Amdovirus, Dependovirus, Erythrovirus, Hokovirus, and Parvovirusand selected for sequence analysis Host
Stain
Accession number
Genus/ genogroup
Human
St1
DQ000495
BoV/HBoV1
Human bocavirus 2
NC_012042
BoV/HBoV2
Human bocavirus 3
NC_012546
BoV/HBoV3
Human bocavirus 4
NC_012729
BoV/HBoV4 BoV/PBoV1
Swine
H18
HQ291308
ZJD
HM053694
BoV/PBoV2
SH20F
JF429834
BoV/PBoV3
F41
JF512473
BoV/PBoV4
JS677
JN831651
BoV/PBoV5
Gorilla
GBoV1
HM145750
BoV/GBoV
Sea lion
1136
JN420360
BoV/CslBoV
Bovine
Bovine parvovirus
M14363
BoV/BPV
Canine Mink
GA3 AMDV
FJ214110 NC_001662
BoV/CnMV Amdovirus
Human
B19
AF162273
Erythrovirus
Human
V9
NC_004295
Erythrovirus
Bovine
HK1
EU200669
Hokovirus
Swine
HK2
EU200672
Hokovirus
Goose
GPV
NC_001701
Dependovirus
Duck
MDPV
NC_006147
Dependovirus
Mouse
MPV
NC_001630
Parvovirus
Swine
PPV
NC_001718
Parvovirus
Fig. 2 Phylogenetic trees of complete genome sequence (a), NS1 (b), NP1 (c), and VP1/2 (d) of strain swBoV CH437 and strains of the five genogroups of PBoV. The trees were constructed using neighborjoining clustering method with 1,000 bootstrap replicates Fig. 1 A neighbor-joining tree constructed using MEGA 5 with 1,000 bootstrap replicates for the full-length genome sequence from members of the family Parvoviridae. The strain swBoV CH437 belongs to the genus Bocavirus
11.9–90.0 % amino acid similarity, respectively. The International Committee on Taxonomy of Viruses (ICTV) has stipulated a species demarcation criteria for members
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of the genus Bocavirus (\95 % sequence identity in nonstructural gene nucleotide sequences). Based on the results obtained we conclude that swBoV CH437 should be classified as a novel PBoV species.
Discussion Porcine bocavirus is responsible for gastroenteritis in swine. Since its first detection in Sweden [9], PBoV has been isolated in America [13], Northern Ireland [15], Uganda [20], Rumania [21], and most notably in China in recent years. In 2010, Zhai et al. [22] reported a PBoV-like virus positivity rate of 38.7 % in pigs suffering from respiratory tract symptoms, and 7.3 % in healthy pigs during a survey of nine provinces in China. In the same year, a serological investigation showed a high prevalence (nearly 40 %) of PBoV-like virus in clinically normal pigs in Hubei Province, China [23]. In addition, Zhang et al. [24] collected 166 samples across ten provinces of China for type testing. Their results showed that four types of PBoV were prevalent in Chinese swine: 28.9 % PBoV1, 6.6 % PBoV2, 19.3 % PBoV3, and 39.7 % PBoV4. According to a report by Shan et al. [25], the positive rate of PBoV detection across five provinces of China was 45–75 %, indicating that PBoV infection in China was both prevalent and complicated. Porcine bocavirus has been detected across a total of 14 provinces in China, including Zhejiang, Jiangxi, Anhui, Hebei, Henan, Jiangsu, Beijing, Shanghai, Xinjiang, Shandong, Guizhou, Fujian, Guangxi, and Hubei. To our knowledge, swBoV CH437 was the first PBoV strain to be detected from Gansu Province, Northwest China. In this study, the complete genome of swBoV CH437 was sequenced and analyzed. The full genome length of strain swBoV CH437 was 5,275 nt; the complete genome sequence of swBoV CH437 shared 24.2–88.6 % nucleotide sequence identity in NS1 region, and NP1 of 21.3–89.9 % nucleotide sequence identity, with representative strains of five genogroups of PBoV. Collectively these results demonstrated that a novel species of PBoV was isolated from swine in Gansu Province, Northwest China. We believe that the results obtained in this study will enrich our understanding of PBoV and will help facilitate future investigations of the evolutionary characteristics of PBoV.
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